artillery firing part 2

8/8/2019 Artillery Firing Part 2

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APPENDICES



APPENDIX 1.

CONVERSION TABLES

FOR

ANGULAR UNITS

TABLE I . — Degrees, minutes, and seconds into grades.

TABLE II . — Grades into degrees and minutes.

TABLE 111. — Gentigrades into minutes and seconds.

TABLE IV — Decimilligrades into seconds.

TABLE V. — Minutes and seconds into thousandths of a

degree.

T I B L E VI. — Degrees into mils (6400) .TABLE VII . — Grades into mils.

TABLES OP METRIC EQUIVALENTS

TABLE I . •—• Linear equivalents.

— II . — Volume and capacity equivalents.

— I II . - - Area equivalents.

— IV . — Weight equivalents.

— V — Approximate metric equivalent.



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3 .E

84 » • a? <N 99



— 190 —

830VU9i d 1 t£> t



Take units of grades from top line, tens of grades fromside column.

Examples : 88G69 = 1408 mils (from main table) .

11 mils (from small table).1419 mils.

1094 mils = 68G (see 1088 in main table).

.38 (see 6 in small table).

68.38 grades.

247G

46 = 3840 (use 24 X 10 = 240).112 (7 grades).

7 (in small tab le, use .44 as nearestmil, all that is desired).

3959 mils.

4793 mils = 300 (4800 mils = 300 grades).

.44 ( 7 mils = .44).299.56



— 192 —

TABLES OF METRIC EQUIVALENTS.

TABLE I.

Linear Equiva len t s .

M m . C m . M K i l o m . I n F t . Y d B. MILE.

_1 . 1 0 0 1 0394 .0033 0011

101 . 0 1

—3937 .032* 0109 —

1000 1 0 0 1 . .001 39 3 7 3 .281 1 . 0936 .0006— 1000 1. 39370 3281 1093. G .6214

25 .4 2.51 0254 — 1 .083 0278 __304.8 30.48 30+8 — 12 1 3 3 3 .00016

91.44 9144 .00091 3 6 3 1 .000571609 1.609 63360 5280 1760 1

TABLE II.Volume and Capacity Equiva len t s .

u. s. U . S.Ou. In . C u. Ft. Ou. Yds. LITERS.

Quar t s . Ga l lons .

1 .00058 .00002 .01732 .00433 .01639

1728 1 .03704 29.92 7.481 28.3246656 27 1 807.9 202. 764.657.75 .03342 .00124 1 .25 .9464

231 . 1337 .00495 4 1 3.78561.02 .03531 .00131 1 075 .2642 1

TABLE III.

Area Equivalents .

m

3HOHH

SQUARE

M UT E 11s.

2 §n 5

*s

SQUARE

FEET.

SQUARE

YARr s.AOBES .

SQUABS

MlZiES.

1 1550 10.76 1 196 00025 _

00065 1 .00694 0008 _ .

09290 144 1 1111 00002 _

8361 1»9fi 9 1 00021 —

4045 43560 4840 1 .001562589998 — 3097600 640 1

1 10000 107649 11961 247



— 193 —

TABLE IV.

Weigh t Equ iva len t s .

K G O z. L B SSHORT

TONS .

LONG

TONS.

M E T R I C

TONS .

1.02835.4536 '

H07.-J

101G1000

35.271

16;aooo35810a527O

2.20-1.0625

1•2000

22402201

.0011—.0005

1

1.121.102

.0009—

.00014

.892U

1.9842

.001•—

.00045

.9072

1.0161

TABLE V.

Approximate Metr ic Equivalents .

Length Equivalents.

1 millimeter = .04 inch.1 centimeter = .4 inch.1 decimeter = 4 inches.1 meter = 10 decimeters = 3 ft. 3 in.(39.37 in.)

1 decameter = 10 meters = 11 yards.1 hectometer = 100 meters = 110 yards.1 kilometer = 1000 meters = 5/8 mile.1 inch = 25 m illimeters = 2 j centimeters.1 foot = 300 millimeters = 30 centimeters.1 yard = 90 centimeters = 9 decimeters.1 mile = 1600 meters = 1.6 kilometers.

To obtain length in inches multiply length in millimetersby 4 and point off 2 decimal places, viz. : 420 mm. x 4= 16.80 inchos. If distance is given in centimeters,proceed as above, pointing off only 1 decimal place.

To obtain length in centimeters or millimeters, dividelength in inches by 4, pointing off 1 and 2 decimal placesrespectively.

To convert kilometers to miles, multiply by 6 and pointoff 1 decimal place (i. e. multiply by 0.6), viz : 11 km.

= 6.6 miles.To convert miles to kilometers divide by 6 and add onecipher, viz. : 72 miles = 120 km. Or multiply distancein miles by 1.6, viz. : 10 miles = 16 km.



— 194 —

Weight Equivalents.

500 grams = 1.1 lbs.1 kilogram = 1000 grams = 2.2 lbs.1 metric ton = 1000 kg. = 2204 lbs.

Volume Equivalents.

1 litre = 1000 cubic centimeters = 9/10 quart1 gallon = 4 quarts = 4.4 liters .



A P P E N D I X 2

Appl ica t ion of the Laws of Dispers ionin Deducing- Methods of F i r e .

888. The m ethods of fire are based on the l aws ofdispersion, which are discussed in pa rag raphs 17 to 28.

389. Trial fire. <— The object of trial fire is to place thezone of dispersion of a single elevation so as to inc lude theobject ive (par. 203). The method consis ts in bracke t ingthe object ive between two verified elevations differingb y 4 field pro ba ble errors (par. 215). Th e ob jectiv e sho uldthen be within the zone of dispersion of the mid-elevat ion of the bracke t .

390. Assume the range as about 5000 meters , and the

range probale error as 25 m ete r s .Trial fire gives a b r a c k e t of say 5000-5100.The zone of dispersion of 5000 is from 4900 to 5100. It

is only known that 4900 is s h o r t and 5200 over. Theobject ive is then between 4900 and 5200, almost cer tainly.

3 9 1 . i uprovement f ire. — The prescr ibed method is tofire at the t r ial elevat ion (pars . 215 and 219), t h a t is,at 5050.

The zone of dispersion for 5050 is between 4950 and5150. Improvement f ire is condi t ional on the zone ofdispersion of the tr ial elevation covering the object ive .If this is no t the case, the ad jus tm en t m us t be begun anew(par. 222), as for example , if the object ive be between 4900and 4950, as A, or between 5150 and 5200, as B.

4950 5050 5150

1 h 1 1 1 1 14900 A 5000" 5100 B 5200

FIG 5 l

What is the probability of this occur ting?In firing at 5000, the probability of a shot being short

of 4950 is 9 % (fig. 51). The probability of having twoshots at 5000 short of 4950 is .09 x .09 = .0081 (par. 26).

which is applicable in this case, since the bracket wasverified.

It is thus seen that the probability of the objective beingwithout the zone of dispersion of the trial elevation, afterhaving obtained a verified bracket of one fork, is veryslight. It is provided for in paragraph 222.



— 197 —

The elevation

gives the shot P 3, whose measured deviation is c3.By similar reasoning, the mean deviation of 3 shots

1 actual and 2 fictitious, is ~ •o

395. Because of the usual inaccuracy in measuringdeviations and the possible intervention of systematicvariations, this method gives only approximate results,and cannot be carried through an indefinitely long series.



APPENDIX 3.

Correction for the inclination of the trunnions.

IB©

>a• 3a

13"

igo

2 0 '

21o

22o

23o

24o

2ao

26o

27o

28o

29o

30o

31o

32o

33o

34o

35o

36»

37o

38»

S9o

40o

INCLINATION OF THE TRUHNIONS (iN MILS) .

Oo 10' 0 ° 2 0 ' 0o30' 0o40' OooO' l°00' lo lO ' lo 20' lo 30' lo40' l°50' 2o 00'

1.0 1.9 2 .8 3.8 4 .8 5.7 6.7 7.7 8.6 9.6 10.6 11.5

1.1 2 .1 3.0 4 .2 5.1 6.1 7.2 8.2 9.1 10.2 11.2 12.3

1.1 2 .1 3.2 4 .3 5.4 C.4 7.5 8.6 9.6 10.7 11.8 13.0

1.1 2.2 3.4 4 .6 5.6 6.9 8.0 9.1 10.2 11.4 12.4 13.6

1.1 2 .4 3.5 4 .8 5.9 7.2 8.4 9.6 10.7 12.0 13.1 14.4

1.3 2 .6 3.9 y . 6.2 7.5 8.8 10.1 11.3 12.6 13.8 15.2

1.3 2.6 3.9 5.3 6.6 8.0 9.3 10.6 11.8 13.3 14.4 15.8

1.3 2 .7 4 .0 5.4 7.0 8.3 9.6 11.0 12.3 13.8 15.2 16.6

1.4 2.9 4 . 3 5.8 7.2 8.6 10.1 11.5 18.0 14.4 16.0 17.4

1.4 3.0 4 . 5 8.1 7.5 9.0 10.6 12.0 13.6 15.2 16.G 18.2

1.6 3.2 4 .6 6.4 7.8 9.4 11.0 12.6 14.1 15.7 17.4 18.9

1.6 q o 5.0 6.6 8.2 9.8 11.5 13.1 14.7 16.5 18.4 19.7

1.7 3.4 5.1 6.9 8.6 10.2 12.0 13.6 15.4 17.1 18.9 20.5

1.7 3.5 5.3 7.2 9.0 10.7 12.5 14.2 16.0 17.8 19.5 21.8

1.7 8.7 5.6 7.4 9.3 11.0 13.0 14.9 16.6 18.6 20.6 22.2

1.9 3.8 5.6 7.7 9.6 11.5 13.4 15.4 17.3 19.2 21.1 23.2

1.9 4 .0 5.9 8.0 10.1 11.2 13.9 15.8 17.9 20.0 21.9 24.0

2.1 4 .2 6.2 8.3 10.2 12.3 14*5 16.6 18.5 20.6 22.9 24.8

2 .1 4 . 3 6.6 8.6 10 9 13.0 15.2 17.1 19.4 SI.4 23.7 25.8

2 .2 4 . 5 6.7 9.0 11.0 13.3 15.5 17.9 20.0 22.2 24.5 26.9

2 .2 4 .6 7.0 9.3 11 5 13.7 16.2 18.4 20.8 23.1 25.4 27.8

2 .4 4 .8 7.2 9.6 12.0 11.4 16.8 19.2 21.6 24.0 26.4 28.8

2 .4 6.0 7.5 9.9 12.5 14.9 17.4 20.0 22.4 24.8 27.4 29.8



APPENDIX 4 .

Use of Meteorological Data.

896. Sources of meteorological data. — In the F renchservice, these are :

(a) A rm y s ta t ion s (1 per a rm y) .

{b) Corps stations (1 per corps). (c) Special stations for long range guns (*).(d) Certain bat tal ions and bat ter ies may be supplied a

barometer and thermometer enabl ing them i f necessaryto calculate the air densi ty.

397 . Nature of the meteorolog ical data supplied. —(a) Te m pera ture and ba rom eter for the m ean a l t i tu deof the region, which is s tated each time.

(b) Ballistic wind for maximum ordinates of 0 (**), 5001000. 1500, 2000, 3000, 4000, and 5000 meters (***).

398. Use (par. 43 and seq.) .— (a) Calculate the correction for air density (par. 43).

Data f rom the army s tat ions gives the weight of a l i terof air corresponding to a relative humidity of 1/2 (oldtables) or 3/4 (new tab les) . Th e w eigh t cal cu late d by t hecorps s ta t ions i s based on the ac tual hygrometr ic s ta te .

899. (b) Calculate the wind correction"as follows :Choose the da ta for the max imu m ordin ate cor respon dingto the range used.

From the fir ing tables, calculate the deflection and rangecorrect ions for the lateral and longitudinal wind components respectively, taken with respect to the l ine of f ire.

400. For t ra jec tor ies whose maximum ordinate i s lessthan 500 meters , use the data for 500 meters .

For maximum ordinates less than 1500 meters , use thecorps data in preference to the army data, because of localvar ia t ions in the lower a tmospher ic s t ra ta .

When the data avai lable does not extend to maximum

(*) Artillery units ordinarily supplied by the army and corpsstations may be at times supplied by special stations of nearbybattalions of heavy artillery.

(**) On the ground.(***) At times the actual wind s given, in which case it is

specifically so stated.The direction from which the wind blows is measured from the

Lambert north or the true north by the east, from 0 to 40 decagpades. For example,, a wind from the east is 10. No wind is 00,



— 200 —

ordinates sufficiently high, use th at for the highest ordinategiven.

401. Data is supplied every four hours, day and night.,beginning at an hour fixed for each army by generalheadquarters.

Use of the barometer and thermometer.

402. The aneroid barometer is a delicate instrument.It must be kept a sufficient distance from the pieces toprotect it from shock.

It should be frequently compared (every 2 or 3 days),by telephone, with the barometer of the meteorological

station, correction being made for the difference in altitude (*).408. Thermometer. — The thermometer should be

placed in the shade. It is best used by .whirling it like,a sling at the end of a string about a half meter long.

404. Calculate the weight of a liter of air by means ofthe charts m the firing tables. A slight error is made dueto the fact that the true hygrom etric sta te is not considered.

(*) When an artillery unit is 'at an alt itude h' differentthan that h for the data furnished, the barometer H' may^becomputed from that given, H, by the following :

H' = .09 (h — h'\, if h is greater than h'.H' = H — .09 (h' — h), if h is less than h'.

If the difference in altitude is more than 100 meters, obtain thebarometer correction from the meteorological station.



APPENDIX 5.

Ballistic Wind.

406. Definition. — The ballistic wind is a fictitiouswind, constant in direction and velocity, which will havethe same total effect on the flight of the projectile as theactual wind, which varies in direction and velocity in the

different atmospheric strata through which the projectilepasses.406. Determination. — It is assumed tha t the disturbing

action of a wind, constant in direction and velocity, ona layer of air of given thickness, say 500 meters, is proportional to the time of passage of the projectile through thislayer.

This assumption is not strictly correct, but it gives a first

approximation.Let T,, Ta . . ., Tn be the times of flight of theprojectile through the successive layers of air each 500 meters thick. In each of these layers, the wind obtained bydirect observation is assumed to be constant in directionand velocity.

Let T be the time of flight.Vx, V2 . ., VB the longitudinal (lateral) wind

component in the various layers.

By taking the weighted mean of the wind componentsin the various layers, the corresponding component of theballistic wind as previously defined is

T T T

Now it can be verified that the ratios

J_" T ' T ""T

are constant for all trajectories of the same maximumordinate, regardless of the elevation, muzzle velocitycaliber, kind of projectile, etc.

A study of the various trajectories further shows tha t if.!'„ T±, and T

i i

be the times passed by the projectile above the altitudesrespectively

F F 3F

4TT



— 202 —

F being the maximum ordinate, then

T i T4

Ti

"rpT = . 8 7 , m~ — - 7 1 , m ~ = . 5 1

regardless of the elevation, muzzle velocity, caliber, andkind of projectile.This property is general. If T ., is the time passed by

»F T

the projectile above the altitude — then -&1= Kp.

Kp being a numerical coefficient.This and similar coefficients for the various layers permit

the determination of the ratios

T, T^ T,tT ' T ' Y

entering into the general expression for the ballistic windcomponent V, previously given.

To illustrate, takes the case where n — 4 :

T 2 T, T ,

T' T

^ = 1 _ J = 1 _ . 8 7 = .13

The expression for the ballistic wind component is then

V = .13V, + .16V.a + ,20V3 + .51V4

407. Similarly it is possible to find by a study of thevarious trajectories the values of the coefficients in thegeneral case of n layers of air. It will be noted th at thevalues thus obtained are essentially the same as, those foundanalytically for t e trajectory in vacuo.

Assuming on this basis that the trajectory in vacuoaffords a sufficiently close approximation, and rememberingthat in this case

F = .5gTa

tb.e coefficient KK — -^becomes K = vn~LpI \Jn.



— 203 —

Thus

T l jn T,|n _ _ y/n — 1 — y/ra — 2

,)>n T,l( . 1• —— X V , , . X V , . — 7 = *

T sln

The general expression for the ballistic wind componentcan then be written :

v /n —_ v /n - - l y/w — 1—y/n—2 J _

V — -

v

l ~ l " y—

v

2 T ^ - " r r -

v

»y /n y/n y/re

408. In practice^ the ballistic wind components for thevarious maximum ord-inates differing by 500 meters can bedetermined at the meteorological stations in the followingmanner.

Determine by direct observation the direction and velocity of the wind in each of the various layers 500 metersthick.

Resolve each of these observed values into componentswith respect to two axes, X and Y, arbitrarily chosen, asor example the Lambert north and the Lambert east.

The ballistic wind components for each of the axes isthen computed by the general expression previously stated.

COMPONENTS OF BALLISTIC WIND.

Or f iMte" L a m b e r t N o r t h

500

v/2-v/ix1000

S-^ ' / i Y , i v

_ A s +y/|

A^ _

V/4-V/C 'V / 3 - V2000

y/42500 and so on.

Lambert Riist.

/o ' 1y / 2 ^

V

1500Z

1

Y+

1Y

y/3 Y ' '

' y / 3 - ,A2

y^-y / i

y/4

2500 and s,o on.

500



— 204 —

The components thus obtained can then be combinedfor each maximum ordinate . The resu ltants are theballistic winds in direction and velocity.

In actual practice, the meteorological stations employcharts or other means which greatly abbreviate the processjust outlined.



PART II

R E C O N N A I S S A N C E

APPENDIX 6.

Procedure in Reconnaissance.

General Remarks.

409. Every reconnaissance begins with a study on themap or "battle map of the area to be reconnoitered. This

study coordinates subsequent work and saves time.The reconnaissance personnel should in every waypossible get in touch with the commanders of units whichhave occupied or are occupying the region itself or itsvicinity. The experience of these officers can thus beutilized to advantage.

These preliminary steps do not ordinarily obviate thenecessity for artillery commanders going over the groundthemselves and personally supervising the units undertheir orders.

By Corpa and Division Artil lery Commanders.

410. Such reconnaissances are tofix he general conditions of the entry into action of the large artillery units.

They are made conjointly with those of the corps anddivision eemmanders.

Corps and division artillery commanders must be perfectly informed as to the nature and condition of theground, the communications, and the defilade, in order tobe able themselves to direct the march, deployment, entryinto action, and supply of their respective units.

The reconnaissance of the terrain as a whole, the objectives, and the observing sectors are made by the artillerycommanders with the assistance of their staffs, immediatelyupon receipt of information as to the engagement of theirunits.

Reconnaissances of command observation posts, command posts, and liaisons are made as soon as the situation permits.



— 206 —

By Regimental and Group Commanders .

411. Each regimental and group commander receives,instructions from the corps or division artillery commanderas to :

The general situation.His M ission.The conditions of his engagement.

He also receives instructions as to the location of thevarious infantry and artillery command posts, the routesto follow, and the liaisons to be established.

Object.

412. The object of the reconnaissance is to determine :Suitable positions and their zones of action.The routes of access.Regimental or group command and command

observation posts.The approximate positions of the terrestrial obser

vation posts.

The plan for telephonic liaisons.In addition, the regimental or group commander shouldestablish relations as soon as possible with the infantrycommander whoVn ha has to support (*).

Execut ion .

413. Depending on the instructions and information

received, the regimental (group) commander studies :The assignment of battalions to the different missions.

The conditions of engagement of these battalions.414. After having given orders for the continuation of

the march and the reconnaissances desired, the regimentalcommander sets out on his reconnaissance accompaniedby (**) :

The reconnaissance officer.The telephone officer.The battalion agents (***).The necessary orderlies.

As soon as he has selected positions for the battalions,the routes of access, and his command post, the regimental

(•) Or with the artillery commander of this infantry unit in

the case of a group of counterbattery artillery.(**) If he deems advisable, he may take one or several battalioncommanders.

(*•*) If the reconnaissance is by automobile, the agents remainat the command post.



— 207 —

commander summons his battalion commanders and givesthem the necessary instructions.

He then sends for the detail and its vehicles, and makesa brief report to the next higher commander on the dispositions made.

415. Upon the arrival of the telephone, topograhpicand radio materiel, and in accordance with the instructions of the regimental commander :

The radio officer establishes the radio station.The reconnaissance officer reconnoiters and establishes

the regimental command and command observation posts.The telephone officer installs the lines connecting the

various infantry and artillery command posts.

By battalion c o m m a n d e r s .

416. Each- battalion commander receives instructionsfrom his regimental (group) commander as to :

The general situation.His mission and zone of action.The position.

Its routes of access.The time of opening fire.The locality for the battalion observation post and

its sector.The liaisons necessary.The location of the various infantry and artillery

command posts.

Object.

417. The object of the battalion commander's reconnaissance is to determine :

The battery positions.The routes of access.The battalion observation post and the objectives.The battalion command post.

The telephone and optical liaisons.When appropriate, the battalion commander enters intorelations as soon as possible with the infantry commanderwhom he has to support.

Subdivision of the reconnaissance par t ies .

418. 1st party.

Battalion commander.Reconnaissance officer.Telephone officer.Scouts and battery agents.Instrument non-commissioned officer.



— 208 —

2nd party.Battery commanders (*).The commander of the combined combat trains.The battery details **).

3rd party.Radio officer.

Surgeon.Battalion and battery telephone details.Transportation of telephones and topographic ma

teriel.Depending on circumstances and the instructions of

the battalion commander, the 3rd party marches withthe 1st party or slightly in rear, or with the 2nd party.(In tractor artillery, the telephone officer usually marcheswith the 3rd party).

Execution.

419. As soon as he has received his instructions fromthe regimental (group) commander, the battalion commander starts on his reconnaissance with the 1st party.Before leaving, he gives the necessary orders covering :"

The timely arrival of the 2nd and 3rd parties.The continuation of the march of the columnr its

route and the method of marking it, the limit ofadvance of the column, the point where it willreceive new orders, the post of the ammunitionsection or combat trains.

420. On arriving in the vicinity of the position, thebattalion commander halts the pa rty under cover. Hethen mak es a reconnaissance, with only the personnelabsolutely necessary, including :

The selection of battery positions (***).The study of Routes of access, their defilade, and

work necessary on them.The selection of an observation post, the reconnais

sance of objectives, and if necessary the area forthe battery observation posts.

The selection of the command post.

421. After this reconnaissance, the battalion commander gives the necessary orders to bring up the 2nd and3rd parties, and the column.

He then reconnoiters a position for the tra ins and decideson the location of the telephone lines.

(*) If one of the battery commanders is left in command ofthe column, his place is taken by the senior lieutenant.

<**) The battery reconnaissance instruments and materiel aredisposed as directed by the battery commander.

(***). When time is important, the reconnaissance of positionsand routes of access may consist simply of general indications, thebattalion commander occupying himself at once with the selectionof an observation post and the reconnaissance of objectives.



— 209 —

He renders a report to the regimental (group) commanderas to the dispositions made and the approximate time ofopening fire.

422. Duties of the reconnaissance officer. — The reconnaissance officer makes the necessary determinations inregard to the battery positions.

He accompanies the battalion commander when thelatter selects his observation post, and locates it accuratelyon the map. He determines an origin line and identifiesa certain number of known points. These are plotted ona rough sketch.

He then determines for the battalion, or for each ofthe batteries, an orienting line; and also the coordinatesof one or more place marks which will enable the prompt

location of the base pieces.Before the batteries go into position, the reconnaissanceofficer furnishes each battery commander in wrining suchinformation as is immediately necessary, particularly thatpertaining to the establishment on the base line, determines their origin lines, and makes panoramic sketches forthem.

He then accurately locates the observation posts.

423. Duties of the telephone officer. — Upon the arrivalof the 3rd party, the telephone officer supervises theinstallation of the telephone system and the laying of suchlines as involve the battalion telephone equipment.

424. Duties of the radio officer. — The radio officercauses the installation of the radio equipment, and supervises the operation of the radio station and that at thebattalion command post.

425. The surgeon reconnoiters a site for the aid stationand supervises its organization.

By battery commanders.

426. The 2nd party , on arrival,halts where the 1st partywas.halted by the battalion commander.

The battery commanders and the train commander

approach the battalion commander, who gives theminstructions as to the following :The general situation.The battery positions and their routes of access.The mission of each battery, its field of action, and

its base point.The position of the battalion observation post,

and sometimes the locality for the batteryobservation posts.

The time of opening fire.The telephone and optical liaisons to be established.The distribution among the batteries of the con

struction necessary (installation of the telephone



- - 210 —

system, the construction of the battalion command and observation posts and of the aki station, etc.).

The positions for the trains.427. Each battery commander then :

Definitely locates the positions for the pieces.Carefully reconnoiters the routes of access to theposition.

Selects an observation post.He sends the executive officer the necessary instructions

for occupying the position.He arranges for the personnel and tools for the necessary

work in connection with organizing and constructing theposition and the observation post, improving the roads,and clearing the field of fire.

He then locates his command pqst and the dugoutsrarranges for the installation of such telephone lines aspertain to the battery, and takes the necessary s»teps to insure supply (*).

If time is important the battery commander selects anobservation post at, once and proceeds to the preparationof fire. In this case, the executive officer puts the ba ttery

in position.428. The commander of the trains reconnoiters the

position for his units, and decides on the routes of supply.He arranges for traffic regulation.

429. The reconnaissance is completed as soon as possible by a study of the close defense of the position, suchus machine gun emplacements and small arms ammunitionsupply, as well as the necessary measures for the use ofthem and other available means.

(*) Careful provision should be m ade for su pp lying hot foodto the personnel at the battery po sition. This is very n ecessary,as these men are subjected to severe fatigue and often deprivedof sleep.



— 212 —

During (a) and (6), the shots must be maintained inthe general case,,on or near the observing line, by compensating changes in deflection, and elevation.

431. Preliminary operations. — Plo t the base piece P(fig. 53), observation post 0, and adjusting point B.

Draw the line OB and P B.On the line PB, lay off Bbx and B62 each equal to a halffork. At bx and bz erect perpendiculars to PB . Theseintersect OB at b[ and b[.

Let w be the angle bfib^, and <? the angle b[Vb'^.o is called the lateral fork, and is the deflection change

necessary to keep the shot on the observing line whenthe range is changed by one fork.

Trial Fire.

432. Bringing the shot on the observing line and trialfire are executed in a manner which depends on whether

F IG. 5 5 .

the observer displacement is less or greater than 3C0 mils(pars. 96 and 105),433. 1st Case. — Observer displacement less than

300 mils (fig 54).Fire two shots with the determine da ta . The center of



— 213 —

these shots will not in general be on the observing lure.Measure the angular deviation a = K^OB.

To bring the center on the observing line, a deflection

K,

change of K^PK' is necessary. An approxim ate valueof this change is

a X

- being calculated in advance (*)

(•) When the observation post is not loo close to the objective,

- can bo determined by the following approximate method (fig. 55):

Tan 9 = approximately

T an

1 _b x 0 B

u>~a~X PBa = b cos t

continued on page 214.)



— 214 —

If this change does not bring the center of the next twoshots on the observing line, the new < enter is treated inthe same manner as the first one Kj. Let K be the firstshot sensed on the observing line.

434. Trial fire is then executed, using elevation boundsof one fork F.

For each bound of one fork, it is necessary to changethe deflection by one lateral fork. The fire is continueduntil a verified bracket of one fork has been obtained.

435. 2nd Case. — Observer displacement greater than300 mils (fig. 56).

Fire two shots with the determined data. The centerof these shots Kx will not in general be on the observing line.Measure the angular deviation (3 = I^OB.

To bring the center on the observing line, an elevationchange corresponding to KiK2 is necessary. An approxi-

Fmate value of K,K,is fix —

p

is calculated in advance (•).

If this change does not bring the center of the nexttwo shots on the observing line, the new center is treatedin the same manner as the first one. Let K be the firstshot sensed on the observing line.

436. It is possible that the changes thus determinedwill be found uniformly too large or too small.

In this case, it is concluded that there is an error indeflection.

FThe elevation changes determined by p x — will be too

Therefore -? = °B

PB cos i9 Distance OB

rw ™ Projection of P B o n OB

(•) p and w should be taken in the same angular unit.F

The following is an approximate method of determining —

t)> being measured in mils and F in meters (fig. 57) :a = F sin i

F sin iO B M

a = OB sin w = 10001000 a

O )

F OB OB OBto ~~ 1000 sin i ~' 1000X

OK•p

Or - = OB in km. x the ratio of OB to the distance of O(X)

rom PB.



— 215 —

large when the line of fire passes between the objectiveand the observation post (*) (fig. 58).

The changes will be too small when the line of fire passeson the opposite^side of the objective from-the observationpost.

In this case, the deflection should be modified to correct

for this discrepancy, according to the principles of paragraph 433.

437. As soon as the shots have been brought onto theobserving line, trial fire is executed, using elevation boundsof one fork, F.

For each change in elevation, a corresponding deflectionbound should be made, equal to one lateral fork (**).

The adjustment is continued until a verified bracket ofone fork is obtained.

438. If the deflection is materially in error, bringingthe shots on the observing line by elevation changes maycarry the fire a considerable distance from the objective.If the latter is close to the friendly line, the fire may bedangerous.

In thiis case, depending on the reliability of the initialdeflection determination, it is advisable to bring the firstshots on the observing line by deflection, instead of elevation, changes.

(*) For the true value of w is then greater than the value usedF..n computing - •

(**) If the lateral fork exceeds 16 mills, the elevation boundshould be reduced to keep the deflection bound within this value.



216

Improvement Fire.

439. The bracket of one fork having been obtained-aspreviously described, the objective is very probably in

B F = B t F, = B

the zone of dispersion of the mid-range of the bracket.The shots establishing the limits of the bracket, being onthe observing line, will have different deflections, thusestablishing a .deflection, as well as a range, bracket-

Improvement fire should be at the middle of both therange and deflection brackets.The deflection thus obtained should be nearly correct.

For this reaso-n, for an observer on the right (left) of theline of fire, all shots to the right (left) of the observing lineare taken as over, and all shots to the left (right) are takenas short.

The adjusted elevation is determined "In the usual

manner (par. 219). This principle is also applicable to thedeflection adjustment.440. Much information in regard to the deflection

adjustment can be derived from a record of the deflectionchanges during trial fire and improvement fire.



=— 21,7 —

It should be remembered that a shot on the observingline sensed over against the objective is to the left (right)of the objective from the position of the piece, when theobserver is to the right (left) of the line of fire. A shot onthe observing line sensed short against the objective is tothe right (left) of the objective from the position of the

K K'

piece, when the obs is to the right (left) of the lineof fire.

441. If the objective has width as viewed by theobserver, shots in the observing sector can be observed for

range even though no t on the observing line. They can alsobe used in the" deflection adjustment as follows (fig. 5tf) :Let MM' be an objective whose adjusting point is B.Let K be a shot fired with the Reflection d, sensed over

and a left of B.



— 218 —

A deflection change of a x - would bring the shot to K',

which would be to the right of the objective from theposition of the piece. The shot K ' need not actually befiredj but the deflection for it should be noted as being to

the right of the objective. This deflection should bethe one to which the lateral fork is applied when the elevation is changed by one fork. The shots at the new elevationshould then be on the observing line.

This also applies to shots which are sensed, even thoughthey are out of the observing sector.



APPENDIX 8.

Bilateral Observation.

442. Bilateral observation consistsi-in the measurementof the angular deviations of the bursts, either air or graze,with respect to an adjusting point, by two lateral observers.These deviations are transmitted to the battery, and serve

as a basis for calculating the deviations in range anddeflection.

Bilateral observation may be by the :a) Graphical method.b) Index method.

4 3 . Graphical method. — The base piece P (fig. 60), theadjusting point B, and the two observation posts D and Gare plotted on the map. Draw the lines BD and BG.

Starting at BD, lay off lines radiating from D at intervals



— 220 —

of 10 mils and extending say 500 meters in both directionsfrom B.

Construct a similar scale with respect to GB.This construction may be on a separate sheet to a large

scale, the lines GB, PB , and DB being transferred by meansof the map squares.

This chart enables the position of a shot to be plotted atonce by means of the observations sent in by the twoobservers.

The fire is conducted by the usual methods (pars. 215and 219 or 228). Range and deflection scales on the chartwith respect to the piece will facilitate reading the changesnecessary.

444. The accuracy of plotting the bursts maybe increased

by using three observers. The intersection of the threeobservations on a burst forms a triangle of error, whichgives an idea of the reliability of the observations.

The observers may refer iheir measurements to anyorigin lines instead of to an adjusting point. Jn this casethe origin lines must be accurately plotted . The chart forplotting shots is then constructed on them.

Index method .445. Range adjustment. — A right (left) deviation for

the right (left) observer is taken as positive ( + )• A left(right) deviation for the right (left) observer is negative (—).In other words, the deviation is positive when it is thesame as the position of the observer, and,negative whenit is opposite to the position of the observer.

The algebraic sum of the two reported deviations is

called the index of- the shot.A positive index means that the shot is over; a negativeindex, that it is short. A zero index means th at the burstis at the range of the adjusting point.

446. Deflection adjustment. — The following is anapproximate rule : From the deviation reported by theright (left) observer subtract algebraically the deviationreported by the left (right) observer, when the materiel is

such that an increase of deflection carries the shot to theleft (right). Add one half of this difference to the deflection.

Examples. — The 75 :(a) Right observer reports : Right 20, right 20,Left observer reports : Right 10, right 10.The phots are over, since 20 + (— 10) == + 10. The

deflection change should be

+ 1 5

showing that the shots were to the right.



— 221 —

ib) Right observer reports Right 10, right 10.Left observer reports : Left 4, left 4.

The shots are over, since 10 + ( + 4) = + 14. Thedeflection change should be

10 — (+ 4)

= + 3

showing that the shots were to the right.

447. Method of fire. — A bracket adjustment is obtainedand zone fire for effect used (pars. 229 and 257).

The size of the bracket sought decreases with the accuracy of the observations, the proximity of the observersto the objective, and the distance between the observers.

The observers should be as nearly symmetrically placed

with respect to the/line of fire as possible.The bracket is always verified (par. 215).

448. Significance of the index. — Draw MM' perpendicular to the line of fire at the objective B (fig. 61).Construct a circle passing through G. B and D. The rulestated in paragraph 446 is based on the following :

Points outisde of the circumference have a positiveindex, as can be seen from the figure, and are taken as

over.Points inside fo the circumference have a negative index,

and are taken as short.Points on the circumference have a zero index, and are

taken as at the range of the objective.



— 222 —

The rule slated for practical use will be In error then forpoints which are between the circumference and the lineMM'. It i/s evident that such errors will OGCUT less, frequently when the two observers are symmetrically placedwith respect to the line of fire, than when Ihey are widelyseparated.

449. Deflection deviations. — The rule stated inparagraph 446 is strictly correct only when the observersare symmetrically placed with respect to the line of fire.

Construct a circle (fig. 62) passing through G, B and D..Let K be the point of burs t. Suppose the piece to beon the circumference.

Barring a serious error in deflection determination, theline P K will be near BP, and the point M will be near the

middle of the arc GBD. It may assumed then, without

serious error, that the deflection change necessary,BPK, is

BPd + BPg



, 223

This is the same as the change called for by the rule whichis

BDrf— (— BGg)2

by the principle of inscribed angles.For a position of the piece, P^ outside of the circumfer

ence, it is necessary to m ultiply the deflection change found"By the rule by the ratio

BPBPx

450. The symmetry of the two observation posts withrespect to the line of fire is not indispensable to the use ofbilateral' observation without maps, but it is* of material

advantage in reducing the depth to be covered in fire foreffect. This condition does not enter into firing by usingthe map.



PART IV.

A P P E N D I X 9 .

Advantage of an Or ient ing 1 L i n e .

451. Formerly the indirect fire of a piece P on anobjective O was accomplished as follows : The rangewas measured directly on the map or determined topographically. In laying for direction a known aiming pointwas used. The sight was set so that when the plane of

sight was directed on the aiming point, the piece was

directed at the objective (or the base point).The firing angle in this case (par. 142) was measured

with the protractor after plotting the points O, P, and Rby their coordinates.

4.V2. This method does not give sufficient accuracy indeflection for the present conditions. The direction ofPO can usually be determined with sufficient accuracy,because O is ordinarily quite distant. But this is not

generally true in regard to PR.To be visible from the piece, R is usually close. Moreover P and R are not often known beforehand and mustbe located at the time. This frequently involves difficultand protracted topographical operations, sometimes quitedistant from the battery.

Practically, the plotted direction PR is usually materially in error (*). and the deflection is correspondingly inerror.

(*) An error of 20 meters in the location of P and R is notunusual. Such errors result from errors in the location of thepoints by which P and R are located, of errors in the operations



— 225 —

468. The necessary accuracy in laying for directioncan readily be obtained if, instead of locating the pointsP and R, the direction PR is directly determined by meansof instruments which are supplied to artillery units (*).

If PR is taken through the sight of the piece, it isnecessary that the piece be in position before the deter

mination of PR, or that the position of the sight be accurately marked and later occupied by the piece. The preparation of fire cannot usually await the arrival of thebattery, but should begin as early as possible during thereconnaissance.

454. It is better not to use PR in laying for direction,but instead to select a line merely passing convenientlynear the piece, and not through it.

The direction of this line, the orienting line, is directlydetermined, and plotted as a direction, not for position.The line PG is determined as previously by the positionof the points P and O.

Laying for direction is effected by setting an instrum ent I(fig. 64) at any convenient point on the orienting line XY.The 0 of the instrument is pointed in the direction 10' parallel to PO as described in paragraph 147. The piece isthen laid in the direction PO by reciprocal laying (par. 148).

455. The use of the orienting line as herein contem

0

plated has other advantages than the saving of time in

the accurate preparation of fire.

performed, and graphical errors. If the errors in P and R arein opposite directions, the error in the direction PR will be 100 milsif the distance PR is 400 meters; 40 mils if PR is 1000 meters ; and20 mils if PR is 2000 meters.

A rapid preparation of fire without previous organization willinvolve even more considerable errors when this method is used;so that recourse should be had to other methods.

(*) I t may be taken that the error of initial deflection determination should not exceed :10 mils for light guns and for howitzers.5 mils for heavy guns.2 mils for high power guns.



— 226 —

It is a general method, and is particularly applicable tothe not infrequent case where a distant aiming pointcannot be used.

The orienting line is permanent, and still utilizable when,for any reason the pieces are moved for short distances.

The determination of the orienting line is facilitated byits being independent of the pieces. If a declinated instrument is used in its determination, it may be set up a t pointsnot near masses of iron. Several points can be used tocheck results and eliminate errors due to local attraction.

The orienting line can readily be common to two or morebatteries, or even several battalions, and the advantagesof a regular sheaf within a battery can thus be extendedto many pieces



— 228 —

The true or geographic north is along the meridian.A point on the ea rth 's surface is defined by its geographic

coordinates, longitude and latitude.The longitude of a point is the angle formed by its

meridian plane with the prime meridian plane taken asthe origin of longitude. In France the prime meridianplane is th at of Paris. Longitude is reckoned from 0 to200 grades, east and west.

The latitude of a point is the angle made by the normalto the surface at this point with the plane of the equator.Latitude is reckoned from 0 at the equator to 100 gradesnorth and south.

459. Map squares and coordinates — All maps usedin firing are provided with kilometer squares, called

Lambert squares, which are numbered on the margin (andsometimes at the intersections).A point is defined by its x and y coordinates, which are

the distances of the point from the X and Y axes respectively of the map.

The abscissae X increase from left to right.The ordinates Y increase from bottom to top.The Lambert or Y-north is the direction of the vertical

lines of the map squares, from bottom to top, using theLambert system of projection.

460. Numerical designation of objectives. — A pointon the map may be designated by a number of 4 or 6 figures.

362

232

The first 2 or 3 figures give the abscissa to the nearesthectometer, and the last 2 or 3 the ordinate.

Thus the complete coordinates of the point shown in

Figure 66 are : x = 362.6309 = 231.880

The numerical designation of this point would 26.19u • 620.319 (hectometric coordinates).



229

This method is used only for the designation of objectives. To accurately define the position of the point thecoiaplete coordinates are used, thus :

x = 362.630y = 231.880

461. Convergence of the meridians. — In the Lambertsystem, the meridians are represented by straight linesconverging toward the north As a result, the geographicnorth and the Lambert north, or Y-line, do not coincide (*).

The angle between these two directions is called theconvergence of the meridians. Its value for a pointwhose longitude is M, east of Paris, is given by the following expressions :

In decigrades : 7.6 X(M—6).In mils 12.16 X(M—6).

If M is greater than 6, the Y-line is east of the meridian.If M is less than 6, the Y-line is west oi the meridian.

462. Y-azimuth. — The Y-azimuth of a line OM is theangle between it and the Y-line, measured from the northclockwise from 0 to 6400 mils, or 0 to 4000 decigrades.

463. Magnetic north. Declination. — A magneticneedle oscillating freely points toward the magnetic north.

Y-Line

True NorthMagnetic

North Convergence

Y Declination^~—

Declination

The declination is the angular amount the magneticnorth deviates from the true, north, (fig. 67 ). The Y-decli

nation is the angular amount tho magnetic north deviatesfrom the Y-line.

(*) E x c e p t for the meridian 6 grades oast , which coincideswith tho Y-linn for which x -= 500000 m.



— 230 —

The declination "varies cont inu ally . At present, inFrance, it is west.

The declination charts give fairly accurate values^ ofthe declination.

For points west of the meridian 6 grades east, the situation is as shown in Figure 67.

Triangulation system. — This is a ne twork of points,easily identified on the ground, and whose position isaccurately kn wn. Some are artificial or na tural markersvisible from a distance (steeples, smokestacks, trees, etc.).Others are simply stakes marking the points of a traverse.

The triangulation system also has decimating points(points de declinaison). A declinating point is one throughwhich several known lines pass, that is, lines which arematerialized on the ground and whose Y-azimuth is known.



APPENDIX 11.

Topographical Methods.

464. The preparation of fire and the organization of

observation involve the following topographical operations :

(af Determination of a line.(b) Location of a point.(c) Determination of the altitude of a point.

Determination of a line.

465. Using a decimated instrument. — This is describedin connection with the use of such instruments (par. 126et seq.).

486. Using an undeclinated instrument (such as theobservation tojescope, aiming circle, or theodolite).

Paragraphs 127 and Appendix 12 describe the orientationof an instrument a t an orienting point.

When an orienting point is not available, any knownline US (par. 127) may be used, by setting up over anypoint U of this line and orienting the instrument bymeans of the known Y-azimuth of the line (fig. 68).

Any unknown line UV may then be determined.



— 232 —

This process is continued until the desired line is reachedand determined.

This process is called an angle traverse (cheminementd'angles), and gives good results under the followingconditions :

The courses, staked out in advance, should be as few

and as long as possible, never less than 100 meters.The instrument should be set up over the line in allcases to within 2 or 3 centimeters.

"The error should then be less than :5 mils, for a traverse of 2 or 3 courses with the plane

table.5 mils for one of 3 or 4 courses with the aiming circle or

observation telescope.

2 mils for one of 5 courses with the Jobin theodolite.With a given instrument, the error in determining a lineincreases with the number of courses. Above a certainnumber of courses, the error of the determination is greaterthan that with a declinated instrum ent. In such a casethe latter method should be used (*).

48 7. Determ ination of a line by tw o kno wn points. —When a declinating point (par. 463) is not available for

declinating the instrument or for beginning an angle traverse, two known points may be used. The line betweenthese points is determined graphically or by calculation.The points used should be accurately known and sufficientlyseparated.

It is preferable to use points of the triangulation system;otherwise distinct points on the battle map, such as asteeple, an isolated building or tree, a road crossing, or

exceptionally the corner of a wood.If the determination is to be used in the preparationof fire, the distance between the points should be comparable to the ranges involved, and to the distances of observation if an observation post is involved.

468. Graphically. — To determine a line graphically,plot the two points accurately with the double decimeter(not with the zinc square or window of the protractor),

join the plotted points, and measure the Y-azimuth withthe most accurate protractor available.By calculation. — If x, y and x', y' are the coordinates of

the two known points, and c the angle between the linejoining the points and the X-axis of the map,

, x" — xtan v = -;

y —yi> is determined by means of tables of logarithmic or

natural trigonom etric functions. The Y-azimuth of the

(*) For the plane table or aiming circle, the number of coursesshould not exceed 2; for the theodolite, i.



— 233 —

line for the point occupied is most easily found by inspection, v being modified by an appropriate number of quadrants (par. 116).

469. By astronomical observations. — The de te rmination of a line by astronomical observations requires a

theodolite. Tne methods are described in T. « ArtilleryReconnaissance Officer.

Location of a point with a declinated plane table .

470. The plane table may be covered with a squaredsheet of drawing paper, in which case the points used inthe work are from the triangulation system or the battlemap, plotted by their coordinates. Or a ba ttle map maybe mounted on the plane table and the know ; points onthe map itself used.

To locate an unknown point on the plane table, thefollowing methods are available :

Intersection )Three-point Requiring sights for direction only.Resection

Direction and distance Requiring distance mea-Traversing surements also.

471 Intersection (intersection) consists in sighting on

the unknown point X from at least two known poi.itsA,B, C, etc.

The plane table having been declinated, set it up at A(fig. 69 )and orient ii. Draw AX. Perform similar operations



— 234 —

at B , C, etc . The lines AX, BX", etc., will in general notintersect in the same point. The center of the variousintersections should be used.

The method is more accurate when the sights are short,mid the intersections approximately a t right angles. Intersections at acute angles (less than about 30°) should be

avoided.472. Three-point. — The location of an unknownpoint X by the three-point method consists in sighting onat least three known points A, B, C, etc, from X.

The declinated plane table is set up at X and oriented.Sight on the known points and draw the correspondinglines from the known points.

The common intersection of these lines is the point X.

As with the method by intersection, short sights andnearly perpendicular intersections are desirable. If thethree known points and the unknown point are nearly onthe same circumference, the method should not be used.

478. If the known points are distant (farther on paperthan the actual length of the needle), or if the plane tableis not accurately oriented, the method must be modifiedby including operations which will not only locate the

unknown point, but also insure the orientation of theplane tab le. Such a procedure is called the unorientedthree-point method (relevement non oriente), and is described in The Artillery Reconnaissance Officer.

474. Resection (recoupement). — This method consistsin locating an unknown, point, which is on a known line,by sighting on at least two known points from the unknownpoint. The known line may be a sight from a known

point, or a line shown on the map.Set up the plane table over the unknown point X, orientit by the declinator, and sight on the known points A, B,etc., drawing the corresponding lines from the knownpoints. The center of the intersections with the knownline is the desired location.

475. Direction and distance. — This method consistsin locating an unknown point X from a known point A,

by determining the direction and distance of X from A.The method may be used directly (rayonnement direct)or inversely (rayonnement inverse).

Directly. — Orient the plane table a t A, sight on X ,draw the corresponding line through A and lay off the distance AX from A.

Inversely. — Orient the plane table at X, sight on A,draw the corresponding line through A, and lay off thedistance AX from A.

476. Traversing. — This method consists in determininga series of lines joined end to end by successive applicationsof the method of direction and distance, starting from aknow point A. The determination of each of the lines



— 235 —

constitutes a course, and the ends of the lines are thepoints of the traverse.

With a declinated plane table, only every other pointof the traverse need}be occupied. Let the points benumbered successively 1, 2, 3, etc.

Set up at A(flg. 70) and locate 1 directly by direction and

distance. Then set up a t 2, which is located inversely by direction and distance.From the same station locate 3 directly bythe same method. Then set up at 4, and Fcontinue the same methods. •"*

The traverse is made to pass through the unknownpoint X, but should continue past it to another knownpoint F ,. The discrepancy between the location Fx b y

-the traverse and the true position F is called the errorof closure and gives an idea of the accuracy of the traverse.

If the error of closure is not excessive, it may be distri

buted among the various points in proportion to theirdistances from the origin A. The point X , will be relocatedat X so that

X X j _ AXF F , AF

If the error of closure is excessive, the traverse should berepeated in the opposite direction.

477. To reduce graphical errors, the traverse may bemade to a large scale (1/5000 or 1/2000). :he traversemay be begun at a corner of a square so selected as topermit the traverse to extend entirely across the planetable. The coordinates of the unknown point may thenbe deduced from its position with respect to the knownpoint A as found by the traverse.

478. A traverse should be as direct or rectilinear as

possible.If. for example, the point 6 (fi«\ 71) can be seen fromthe initial known point A, 6 should be used as a stationand a sight taken on it from A. The interm ediate stations 1, 2, ?>, otr.., will then be needed only in connection



— 236 —

with stadia measurements of distance and slope if necessary. The plane table need not, in this cas , be carefullyset up since it serves only to support the telescope alidade.

A e A

FIG. 7 1 .

This effects a saving of time and increases the accuracy.The point 6 is plotted by its direction as established

from A and by the total distance as determined fromthe traverse.

479. Traversing by back sight and fore sight. — When

the plane table is not declinated, or is imperfectly declinated, or when local attraction is feared, all of the stationsof the traverse must be occupied. The plane table isoriented at the known point by sighting on other knownpoints. The first station is then located by direction anddistance. Orientation at the second station is by a backsight on the initial station. The third station is locatedby direction and distan.ce from the second. The processis continued in this manner.

., The plane table must be set up carefully, with thestation on the map accurately over the stake on the ground.Short courses must be avoided.

Location of a point with a declinatedtheodolite or aiming circle.

480. The declinated theodolite or aiming circle may

be used for the operations previously described (pars. 470to 479 for the plane table.The observations and measurements are recorded, and

the results are determined afterwards graphically or bycalculation.

481. Operations on the ground. — At each station theinstrument is oriented by the declinator. The readingfor direction is then the Y-azimuth.

The observations, azimuths, distances, and slopes ifneeded are recorded, preferably in diagrammatic form.

482. Graphical solution of the work. — This work isgenerally done on a drawing board, with the protractorand the rule or double decimeter. The constructionsincident to the methods of intersection, three-point,resection, direction and distance, and traversingare entirelysimilar to those made on the ground when the plane tableis used.

Calculation. Calculation of the results is not ordinarilyemployed for work with a declinated instrument. Themethods arc described in The Artillery ReconnaissanceOfffcw.



— 237 —

488. When the Y-declinatiori is not known, the samemethods may be used, but it is, necessary, either during thework or afterward, to sight on a known line. A comparison of the reading of the known line and its Y-azimuthwill give a constant by which the directions recordedduring the work may be converted into Y-azimuths.

Location of a pointwith an undeclinated goniometer.

(Observation Telescope theodolite without a declinator, or aiming circleor compass theodolite in a region subject to magnetic disturbances.)

484. The operations in this case, like those of paragraphs 480 et seq., consist of measurements on the ground,

which are afterwards resolved either graphically or bycalculation.

485. Intersection (par. 471). — Set up at a knownpoint A with the 0 of the instrument in any direction.Sight on the unknown point X using the upper motion, andalso on 2 or 3 known points as distant as possible. Notethe readings for these sights. A comparison of these react*

5

ings with the Y-azimuths of the known lines read will give a

constant by which the Y-azimuth of the line AX may bededuced, and plotted from A.

A similar operation is effected at the other knownpoints B, G, etc.

486. Three-point (par. 472). — Set up at the unknownpoint X, and sight on 4 or more known points, using theupper motion. Note the readings. The points selectedshould be as close as possible.

Lay off these readings from a point on a separate pieceof tracing paper. Place this on the map or other plot ofthe known points, and move it about until the linesrepresenting the sights taken all pass through the knownpoints visible through the tracing paper. Prick throughthe point on the tracing paper. This is the location of theunknown point.

This method is the simplest solution of the three-pointproblem, and also the least accurate. Other methods

are explained in The Artillery Reconnaissance Officer.487. Resection (par. 474). — Set up at a known

point A, and read the unknown point X, as well as 2 or 3known points as distant as possible, using the upper motion.

Then set up at X, and in the same manner read A and 2or 3 known points as close as possible.

Plot the line AX in the same manner as for intersection(par. 485). Determine the Y-azimuth of AX from the

readings at A. The Y-azimuths of the readings of theknown points taken at X can then be determined fromthe Y-azimuth of AX. The sights from X on the knownpoints can then be plotted from the latter "points byniouiis of their Y-azimuths.



— 238 —

488. Direction and distance (par. 475). — The directionof the unknown point X is determined and plotted froma known point A, in the same manner as for intersection(par. 485). The distance AX is measured directly and"laid off from A.

489. Traversing (pars. 476 to 479). - The method byfore sight and back sight is used, it being necessary tooccupy all of the stations.

Set up at a known point A and sight in succession on 2or 3 known points as distant as possible and also on thefirst station 1, using the upper motion. Increase thereading on 1 by 200 grades or 3200 mils.

Set up at 1. Set off this reading on the instrum ent and,using the general motion, back sight on A. The 0 of theinstrument is then in the same direction as at A. Thensight on the second station 2. Incr ase the reading bya semi-circle as before, and proceed to the next station.The process is thus continued.

In constructing the traverse, the Y-azimuths of thein ow n lines read at A afford a means of deducing a constantBy which all readings for direction can be converted toY-azimuths, since the 0 of the instrument had the same

Y-azimuth throughout the operations. A large scale ofsay 1/2000 should preferably be used.

490. When a theodolite is used in connection withknown points of the triangulation system in applying these,methods, the observations are best resolved by calculation.The methods are described in The Artillery ReconnaissanceOfficer.

Determination ot the altitude of a point.

491. The altitude of a point can usually be readdirectly from the map by means of the conto rs. If thereis no contoured map, or if there is reason to question theaccuracy of the contours available, a levelling operation isnecessary, based on a point of known altitude . The

methods used may be :Measurement at the point of unknown altitude Xof the angular elevation of known, points A, B, etc.

Measurement at known points of the. angular elevation of the unknown point.

Traverse from a known point, with measurementof slopes, closing on another known point.

When haste is necessary, by barometer.

Whatever method is used, the points involved shouldbe as close together as possible.

492. Known points may be bench marks or any othermap details whose altitude is accurately shown on themap. The altitude of points along a water courso can be



— 239 —

arrived at sufficiently accurately from bench marks alongthe banks at intervals as great as several kilometers.

498 Levelling by measuring the slope. — Th e differencein level between two points can be found from their angulardifference in level and the horizontal distance betweenthem.

Let H be the altitude of the ground at the point occupied.

II the altitude of the ground at the point sightedupon.

h the height of instrument at the pointoccupied.

h' the height above the ground of the point

sighted upon.i the angular difference in level.D the horizontal distance between the two

points.

The points should not be more than 4 kilometers aparton account of refraction. When the point of knownaltitude is occupied, the unknown altitude may be foundfrom

H' = H + D ta n t + (h — h')When the point of unknown altitude is occupied,

H = H' — D tan i — (h — h')

494. Calculation of D tan i. — With the telescopealidade,the slide rule of the alidade m y be used. Direct calculation with natural or logarithmic tangents may also beused.

When i is not too large, i may be substituted for itstangent.

When i is in mils and D in kilometers,

D tan i — D i, or more accurately .982 x D x iWhen i is in grades, and D in kilometers,

D tan i — 15.7 x D x iWhen i is in degrees and D in kilometers.

D tan i = 17.4 x D x i495. Levelling by barometer. — If h — h0 is the diffe

rence in barometric pressure at two points, the differencein level between the two points in meters is

Z = k x {h — h0)

where k is a coefficient which varies with the mean barometer and the mean temperature of the two points.

The following table gives the values of k for the variousvalues of the mean temperature -—~—— a d mean

It

barometer (*~t*< > ):



240 —

Value of k.

MliAN TKMPEHATlinE. — <:.

511SAN BAIlUMETJSll.

780770760

750740730720710

700690680

670660

— 1 0 «

9.8710.0010.13

10.2610.4010.5410.6910.84

11.0011.1611 32

11.4911.67

Oo

10.2410.3810.52

10.6610.8010.9511.1011.25

11.4111.5811.75

11.9312.11

1 0 o

10.6210.7610.90

11.0411.1911.3511.5111.67

11.8412.0112.18

12.3612.55

2 0 °

10.9911.1411.29

11.4411.5911.7511.9112.08

12.2512.4312.61

12.8013.00

3Oo

11.3711.5211.67

11.8311.9912.1612.3312.50

12.6712.8513.04

13.2413.44



APPENDTX 12.

Instruments.

496. Firing board (planchette de tir). — This is a drawingboard of wood or wood and zinc, covered with squared paper.

The orienting line, base piece, base points, objectives,datum points, witness points, observation posts, etc., areplotted on it.

It is used for the constructions and measurements incident to the preparation of fire.

A battle map may be used instead of the squared paper.

497. Protractors (rapporteur). — Protractors are semicircular in zinc or celluloid. They are used for measuringor laying off angles. The graduations are in mils, decigrades, or R-mils. The accuracy of a protractor increaseswith its size.

In measuring a firing angle (or ) ase angle), when theprotractor is graduated in the same direction as the deflection scale of the sight, the 0 of the protractor is placedon the desired line of fire (base line). The reading is madeat the line of sight (orienting line). If the angle is greaterthan a half circle, a half circle must be added to the readingof the protractor.

When the protractor and si^ht are graduated in oppositedirections, the 0 of the protractor is placed on the lineof sight (orienting line), and the reading made at the lineof fire (base line), increased if necessary by a half circle.

In measuring the Y-azimuth of aline, when the protractor

is graduated clockwise, the 0 of the protractor is placedon the Y-lino, and the reading made at the line whoseY-azimuth is desired. The reading is increased by a halfcircle if necessary.

If the protractor is graduated counterclockwise, the 0is placed on the line whose Y-azimuth is desired, andthe reading made on the Y-line. The reading is increasedby a half circle if necessary.

498. To draw a line of given Y-azimuth through apoint A. — Draw a Y-line through A by means of measuredoffsets from the nearest Y-line equal to the offset of A.Deduct a half circle from the Y-azimuth if it is greater thana half circle.

If the protractor is graduated clockwise, place its 0at the Y-line, and mark the position of the desired lineat the proper graduation.

If the protractor is graduated counterclockwise, place

the given reading at the Y-line, and mark the desired lineat the 0.

499. Parallax protractor. — This is a pro t r ac to r of



— 242 —

large radius, covering only a small angle. The radii ofl,he graduations are drawn full length. They are alsograduated in distance from the center.

The celluloid form is 85 cm. long. Its distance graduation is to the scale of 1/20000.

The tracing paper form is used to measure small angleson a large scale map, when the center is off the map. Themap must have a radius on it and a point whose lengthof radius is known. The pro tractor need be only partiallyunrolled, so as to expose the portion corresponding to theknown length of radius.

The white paper form is 4 meters long and is used todraw angular graduations on a map, when the center isoff the map. The map is laid on the protractor, and a

straight edge reaching across the map is used to connectthe uncovered portions of the radii of the protractor.500. Map square (equerre en zinc). — This square is of

zinc, and is graduated to 1/20000. It is used to measurethe coordinates of a point on the battle map, or plot apoint of given coordinates.

501. To measure the coordinates of a point (par.459). — To measure the coordinates of A (fig. 72),

apply the square with the horizontal graduated edge alongthe X-line and extending to the left of A, and the vertical361

232

graduated edge passing through A. Read the fractionsof a kilometer which must be added to the kilometriccoordinates.

502. To plot a point of given coordinates. — Let thegiven coordinates be :

x= 362.280y = 231.650



— 243 —

Apply the square as be'fore, with the horizontal graduatededge along the X-line for which Y = 231. Slide thesquare along this line until the graduation 280 is at theY-line for which X = 362. Mark the required point atthe graduation 650 of the vertical graduated edge.

•603. The zinc decigrade protractor has a window whichis the same as a map square.

To plot a point accurately, the double decimeter scaleshould be used, and not the map square or protractorwindow.

504. Straight edge (regie a dessin). Scale (regie graduee). Double decimeter (double decimetre). — These are

used to draw straight lines and measure distances. Thestraight edge of thejjrotractor may be used if it is true.

Plane table. — Telescope alidad,e.

Slope rule alidade.

505. The plane table is a device for performing topographical operations by direct graphical constructions.

The plane table is'covered with squared paper or a battlemap. The use of the plane table involves either :

The telescope alidade and stadia rod, ofThe slope rule alidade and steel wire (or decameter tape).

506. To set up and level the plane table. — In setting upthe plane table, it should be placed so that point occupiedis directly under the corresponding point on the-plane table.

In levelling with the slope rule alidade, the alidadeshould be placed parallel to two legs of the tripod. Thesetwo legs are then seated so as to center the bubble of thealidade. The alidade is then placed perpendicular to itsfirst position, and the third leg moved so as again to centerthe bubble. These operations are repeated until the bubbleis centered for all positions of the alidade. The tripod legsshould be clamped before the final verification of theoperation. They should be undamped before the tripod

is closed for transport.With the telescope alidade, the operations are the same

except that but one position of the alidade is necessary,since the level is a spherical one.

If the plane table is not level, the angles constructed arenot horizontal ones, and the declinator needle will notoscillate freely.

507. To orient the plane table (par. 117). — Set up the

plane table over a known point A, from which severalother known points B, C, etc., can be seen. Let a, b, c,etc., be the corresponding plotted positions of these points.Set the alidade on the line say ab, loosen the plane table,turn it so that the alidade is sighted on B, and reclampit. Verify this orientation by similarly placing the alidade



_ 245 —

When the stadia rod is not all visible when held vertically, it may be held horizontally, and perpendicular tothe line of sight (*). The horizontal scale of the reticuleis then used.

When the distance is less than 25 meters, use the stadia

rod 1 meter long (**), and divide the distance read by 2.514. (b\ With the 20 meter tape. — Two men are

necessary. The forward man carrjes a bundle of iron orwooden stakes, and is lined by the rear man. Each lengthis marked by a stake. The rear man pulls up the stakeas he leaves it in going on. This gives a means of countingthe lengths.

In moving forward, the tape is held taut and not allowed

to drag.If more accuracy is desired, the measurement can berepeated in the opposite direction. The discrepancy shouldnot be more than 1/1000 of the distance. When this secondmeasurement is not considered necessary, gross errorsshould be avoided by pacing the distance. This willat least insure detection of an error in counting the numberof lengths.

515. To measure a slope, (a) With the slope rulealidade. — Center the bubble by means of the cams. If theslope is ascending, use the lower peep and the right edgeof the sli t; if descending, the upper peep and ' the leftedge of the slit. The graduations are 10-mil, but milscan be read by interpolation.

The middle peep can be used with the same scales, butthe slope read should be decreased 200 mils.

516. (b) With the telescope alidade. — Bring the pointmeasured on the grade scale of the reticule. Center thebubble by means of its screw.

Read to 5 grades on the external scale, and the gradesand centigrades on the reticule. The total reading, less100 grades, is the slope with its sign.

In measuring a slope, the point read should ba at theheight of the instrument.

Aiming circle (Goniometre-boussole) Model 1916,Model 1917.

517. Deseription. — The aiming circle is an in s tru m en tused for the p re pa ra tio n of f ire. Th ere are two models

(*) This condition ia difficult to obtain, and the horizontal rodshould not be used, unless the vertical position is not entirelyvisible even with the rod raised off the ground.

(**) With the folding stadia rod, a 1-meter base can' be hadbetween one mark and the bolt which unites the two halves of therod.



— 246 —

in mils, which differ only in a few details. They aredesignated as the Model 1916 and the Model 1917.

The telescope is a small prismatic one of 4-power, anda large field of view. The Model 1917 has a focussingeyepiece O. The telescope and declinator are mountedon the upper motion Q.

The telescope has a movement in a vertical plane (whenthe instrument is level), which is essentially parallel tothe index line of the needle. It can be leveled independently of the rest of the instrument, by means of a levelV fixed to it. It is actuated by a worm U.

The reticule has a vertical line for sighting in direction,and a site graduation from — 100 mils to + 100 mils. Theaxis is at the intersection of the vertical line and the 0

of the sight scale.In the Model 1916, there is a dotted graduation to theright of the vertical line giving the normal height of burstof 3 mils (par. 240). In the Model 1917, there is a stadiascale in meters for use with a 2-meter stadia rod.

518. The declinator has a needle release D, by meansof which the needle can be raised from the pivot fortransport. For transport, the lever should be to the right.

There is a small prism for magnifying the needle index.In the Model 1917 only, the needle index is adjustable bymeans of a small screw* near the prism Support. Thispermits instruments to be accurately standardized.

519. The general motion is either rapid, by looseningthe clamp C, or slow, by the worm S with C tightened.

The upper motion, carrying the telescope and declinator,is either : slow, with the worm W engaged, by means of

the milled head T; or rapid, by disengaging the worm W,which is eccentrically mounted.If the worm does not engage under the action of its

spring when released, do not force it, but turn the milledhead T slightly, when it will drop into engagement.

520. The tripod consists of three telescoping legs anda sliding vertical support, which is clamped by the screw B.

The aiming circle is fixed to the tripod by a ball joint R,

clamped by a screw G. It is levelled by a spherical level H,fixed to the general motion.With the Model 1916, for accurate work, the vertical

support of the tripod should not be extended. This isnot necessary with the Model 1917, which can be fullyexteiidpd, giving heights from 0 m. 80 to 1 m. 80.

521. The graduations are con tinuous from 0 to 6400 mils.Hundreds of mils are read on the graduation on the general

motion at the black index X. Units are read on themicrometer at the index Y.In the Model 1916, this graduation has a double num

bering, the red ligures being for a clockwise graduationand the black figures for a counlerrluckwis"1 v,ia<luation.



Aiming circle Model 1916.



Aiming circle Model 1)916.

FIU. 7/,.



In the Model 1917, there is only the red numbering, fora clockwise graduation.

Since the aiming circle is primarily intended for the75 gun, a special scale is provided which permits an angleto be read directly in the units of the sight graduation

(plateau and drum ). This is used for reciprocal laying,as explained in paragraph 148. The 0 of the principalscale corresponds to plateau 0, drum 100 of the specialscale.

One of the quadrants of the upper motion is dividedinto eight equal pa rts marked PI. 0, PI. 2..., PI. 14. Fourindices on the general motion are provided for this scale.They are triangular black marks at 0, 16, 32, and 48, ofthe general motion. The plateau is read on the specialscale at whichever index is covered by the scale.

Each plateau division of the special scale is divided intotwo halves, one clear and the other cross hatched in red.If the plateau index is at a clear portion, the mils are readon the micrometer at Y, and will be between 0 and 100.If the plateau index is at a cross hatched portion of thespecial scale, the mils are read at the index Z (marked byred cross hatching), and will be between 100 and 200.

522. A lighting device for night observation is provided,consisting of a cell box and cell, a rheostat, a switch,connections, and a bulb. The lamp is attached to theleft telescope support so as to throw light on the scale inthe field of view through the window F. The lamp canalso be used for lighting the scales and the declinatorneedle.

When this device is not available, an ordinary pocket

flash light can be used.523. To set up the aiming circle. — Set the tripod so

that the axis is over the desired point on the ground, withthe sliding support vertical. Loosen the clamp G, andlevel the instrument with the spherical level H. Tightenthe clamp.

524. To orient the instrument by sighting on knownpoints. — The orienting point used (par. 127) may be a

declinating point (par. 463), or any point O from whichseveral known points can be seen. If a declinating pointof the triangulation system is used, the known lines forits are listed with their Y-azimuths.

If any other known point is used, the Y-azimuths ofthe known points seen from it must be determined bycalculation or graphically (par. 468). Let these valuesbe a, [i, y, etc., for the lines OA, OB, o<!, etc ., respectively.

Sit up at O, with the instrument set at a on the continuous red graduation. Lousen the clamp C of the genii.ilmotion, and point, the telescope roughly at A. Tighten (',and sight accurately on A by means of the slow motionworm S of the general motion.

Without disturbing the general motion, sight on the



— 250 —

known points A, B, C, etc., and again on A. Note the readings for each. Let them be represented by a', (B', y', etc.If the readings are not at variance with the correct Y-azimuths by more than 1 mil, the instrument is oriented.If the discrepancies are more than 1 mil, take the meanof the differences a—a', [j—(3', y—y', etc., designated as s.

Then move the general motion by s in the appropriatedirection, and repeat the readings on the known pointsas previously explained. Continue this process until thereadings obtained are the correct Y-azimuths.

In making the sights on known points, the points shouldalways be approached in the same direction.

525. To decimate the aiming' circle. — The instrumentis oriented as just explained, then bring the needle indexopposite the needle by means of the upper motion, beingcareful to secure accurate coincidence. Note the reading.Repeat this operation several times, and take the mean ofthe readings, which is the declination constant for this particular instrument. Record the value on the instrument.

If the instrument is used in another locality, it mustbo redeclinated.

The Y-declination given by the map can be used only

as a rough approximation. As a matter of fact, the telescope is not necessarily accurately parallel to the needlewhen the latter is opposite its index. The discrepancyin this respect may be as great as 20 or '60 mils (*).

526. To orient si decliuated instrument. — Set theinstrument at its declination constant and, by means ofthe general motion, bring the needle accurately oppositeits index.

527. To detenuitic the Y-azimuth ol a line AB. — Setup the instrument at any point A of the given line, andorient it. Sight on B, using the upper motion. Thereading on the continuous red graduation is the Y-azimuthof B from A.

528. To measure an angle. — .The angle between twolines may be obtained by measuring and subtracting the

(*) But with the Model 1(J17, having an adjustable needle index,

the instrument can be adjusted so that its declination constantwill be any desired value, such as the Y-azimuth of the magneticnorth, given on the battle map.

Let a be the Y-declination (par. 463). Then the Y-azimulh ofthe magnetic north V,,, is.

Vm — 6400 — a

Orient the instrument accurately as described in paragraph 512'J.Then, without disturbing the orientation, set the instrument atVw. Adjust the needle index to accurate coincidence with theneedle.

Such an adjustment is of pm'tiea] value only in standardizingtwo or more instruments.



— 252 —

Observation telescope.



— 25.1 —

Y-azimuths of the lines. If this angle is all I hat is required,it is unnecessary to orient the instrument. The followingis sufficient.

Set up at O, and sight on the left point, using the general motion. Then point on the right point, using the

upper motion. The reading of the continuous red scaleis the angle between the two lines.

_529. To measure the site. — Point the instrument sothat the objective is on the vertical scale of the reticule.Level the telescope. Read the site on the reticule, beingcareful of the sign.

630. To measure a distance. — With the model 1917aiming circle and the 2-meter stadia rod, the operation

is the same as with the telescope alidade (par. 513a).With the model 1916 instrument, read the vertical(preferably) angle L subtended by the stadia rod, bymeans of the mil-scale in the field of view. The distance Dis given by the expression :

where K is a constant (about 2000) previously determined(*)•

Observation telescope.

(Longue-vue monoculalre.)

531. The prismatic observation telescope is used for

observation, principally at long range, and for the preparation of fire.

Model 1917 (Type X. Campagne, modele 1917), formateriel having a sight graduated in 6400 mils.

Model 1916 R (Type X. Campagne, modele 1916 R),formateriel having a sight graduated i : R-mils (6000 to thecircle).

Siege and position (Type X. Siege et place), for materielwith the siege goniometer.

The other models are similar t > one r f these, differingonly in small details.

532. Features common to the three types. — There arethree eyepieces, mounted on a tu rret. The powers are 15.23, and 30.

The 15-power is suitable for use on dark days, or at

(•) .To determine K, tape three distances on the ground of 25 m.,30 m., and 40 m., from the instrument. Measure the angles subtended by the stadia rod held vertically at these three distances.These values should be about 80, 67, and 50 mils, respectively.For each value, find the product D x L. Take K as the mean



— 254 —

twilight or dawn. The illumination is superior to thatof the higher powers (*).

The 23-power is the normal one for use on a clear day.The illumination is somewhat greater than that of an8-power field glass.

The 30-power is superior on a very clear day for long-range observation.The telescope is mounted above a goniometer, which is

fixed to a tripod. It has a movement in elevation, and asitonvler.

533. Both the general motion and the upper motionhave slow and rapid movements, generally similar to thoseof the aiming circle (par. 519).

534. Graduations. Model 1917. — There is a clockwisegraduation, 0 to 6400 mils, similar to that of the aimingcircle (par. 521) (**).

The site device is operated by the worm U. The graduation is in mils. The hundreds are read on the disk V,.and the units on the micrometer Z. There are two setsof graduations, one in black for positive sites, and onein red for negative sites.

The reticule has a cross in the center, marking theoptical axis; and two scales, one horizontal and the othervertical, with 5-mil graduations. The normal height ofburst, 3 mils (par. 240), is indicated between the cross anda special graduation.

Model 1916 R. — There is a single continuous graduation,from 0 to 6000, and a double numbering in red and black.The former is clockwise, and the latter counter-clockwise.There is no special scale. The, site device and the reticule

are the same as for the model 1017, except that they are.graduated in R-mils.

Siege and position. — There is a continuous graduationin decigrades, from 0 to 4000, with a double numbering :red, clockwise; and black, counterclockwise.

The sitometer is graduated in degrees and minutes. Thegraduations are to 5 degrees on the disk and to 5 minuteson the micrometer. The graduations are numbered-in

black for positive sites, and in red for negative sites.The reticule has a horizontal scale in single decigrades,

and a vertical scale with 4-mil graduations.

535. To set up the instrument. — R e m o v e the t r ipod

(*) The illumination is proportional to the square of thediameter of the emergent pencil of rays, which can be seen as asmall circle of light when the eye is placed a short distance (6 or

8 inches) from the eyepiece. The diameter of the emergent pencilis the effective diameter of the objective of the telescope dividedby the power.

(**) The model 1917 is intended primarily for the 75 gun, and isprovided with the special scale for reading plateau and drum(par. 5:51).



Tripod and goniometer of observation telescope.



— 25 fi —

and goniometer from the case, taking care to see that theyare locked together by the clamp C.

Extend the tripod legs to the desired height, and embedthem firmly in the ground.

Level the goniometer by means of the ball and socketjo in tR and the spherical level H . The join t is locked by

the winged nut G.Remove the telescope mounting from its case, and placeit on the pivot'I of the goniometer, first loosening theclamp E by pressing down the lever. Engage the studJ in its recess. Tighten the clamp E.

Place the telescope on its mounting and secure it.

536. To use the telescope. — Use the eyepiece which isin prolongation of the axis of the telescope. Focus the

eyepiece. Its graduation is in diopters (*),The power may be changed by revolving the turret Bcarrying the 3 eyepieces. The turret is secured in itsthree positions by a spring catch. The catch releasesupon the application of pressure to turn the turret, andreengages when the turret is in a position for use.

In dismounting the telescope, the 15-power eyepieceshould be set for use. The clamp G shouldbe securely

locked.537. To measure the angle between two points. — Ifboth points are simultaneously visible through the telescope, the reticule may be used.

Otherwise, set the instrument at 0, and sight on theleft point by means of the general motion. Then sighton the right point, using the upper motion.

The reading on the continuous red graduation is the

angle desired.If the graduation is numbered both in black and red,the first sight may be on the right point. In this casethe final reading on the black scale is the angle desired.

538. To measure the site. — Set the instrument on theobjective, using the vertical motion and the crosshairs ofthe reticule. Level the sitometer by means of the wormactua ting it. Read the site (par. 532).

539. Use in observation of fire. — Set the instrumentat 0 on the adjusting point, using the general motion.

The deviation of the burst, and its height if desired,can ordinarily be measured on the reticule. When theburst is out of the field of view, it can sometimes bepicked up by rapidly moving the instrument with theupper motion. In this case the reading would be~on the

(*) A diopter is an unit used in expressing the refractive powerof lens. A person who requires a concave spectacle lens of1 diop ter for seeing distant objects would, in focussing a telescope,set the eyepiece at — 1. Similarly, for a convex lens the settingwould be +.



— 257 —

external scale. The setting should be verified when theinstrument'is returned to the adjusting point.

540. Use for general observation. — When used in anobservation post, the instrument should be set at 0 on aspecified origin line (par. ; 4), or oriented, a cording to theorders received. The observations are reported by the

reading on the continuous red scale, the instrument beingpointed by means of T.he upper m otion. The orientationshould be verified from time to time.

Scissors telescope.(Longue-vue binoculaire.)

541. The scissors telescope is a binocular prismatic

instrument for the reconnaissance of objectives and theobservation of fire. It consists of two telescopes mountedon a common pivot so as to be capable of rotation in alateral vertical plane.

The arms may be disposed horizontally for stereoscopicvision, or vertically for periscopic vision. With the armshorizontal, the distance between the objective lenses isabout 10 times as great as that between the eyepieces.

The objects viewed are thus brought quite strongly intorelief, unless they are too distant.There are three principal types of the instrument :

Model 1917, in mils.Model 1916 R, in R-mils.Siege and position, in decigrades, for material using

the siege goniometer.

542. Features common to these three types. — The

power is 12. The illumination is somewhat greater th anthe service 8-power field glass, and permits observationin poor light, as at dusk or daybreak, or on dark days.

The right eyepiece has a reticule, which can be rotatedby a milled collar on the outside so as to be in the proper position for any position of the arms.

The instrument can be moved in elevation, and has asitometer. It is mounted on a goniometer, which is inturn mounted on a tripod.

543. The goniometer, sitometer, and the reticule areof the same type and with the same graduations as thecorresponding types of observation telescopes (pars. 532to 541).

544. In the older models, the goniometer has no micrometer. The types A, B, BC, D, and E are graduatedin mils.

The types DD, F, G, H, and I have two graduations,one in mils and the other in decigrades. The sitometeris in mils. The reticule has an upper horizontal scale indecigrades, a lower horizontal scale in mils, and a verticalscale in mils.

AHT1LLEKY FINING 17



— 258 —



OKQ

Scissors telesoope, type D. Periscopic vision.

FIG. 7 9 .



— 260 —

545. To set up the scissors telescopel — This operationis similar to that for the observation telescope (par. 535).The telescope and its mounting are united.

Each eyepiece is focussed separately.After the eyepieces are focussed, the arms are set by

loosening the clamp of their pivot and moving the armsby hand until the two fields of view are accurately superposed, the arms being horizontal or vertical as desired.The pivot clamp is then locked. When properly adjustedin this manner, the object viewed will be seen with themaximum brilliancy. The pivot is graduated in millimeters, so that when the arms have been set for an individual observer, he can note the setting for future use.

546. To dismouut the telescope. — The arms areundamped and folded down on the mounting to the left.The pivot is left undamped. Place the telescope and itsmounting in the case with the objective lenses on the sideof the cover hinge.

In putting the tripod in its case, see that the clamp Cis firmly locked.

547. The operations of measuring sites and angles,

and observing are similar to those with the observationtelescope (pars. 537-540).

Field glasses.

548. Field glasses are used for general observation orfor the adjustment of fire. They have reticules for themeasurement of small angles.

The type most widely used is 8-power.The higher powers, such as 10, 12, and 16, can be used

successfully only exceptionally, because the field of viewis small, the illumination poor, and it is difficult to holdthem steady. A support can be used to overcome thislatter difficulty.

Sighting circle.

549. The sighting circle is an observing instrument soarranged as to permit the measurement of horizontal angles.

It consists of a semi-circular wooden table, with a pivotat the center. The table carries a zinc protractor in milsor decigrades, and has a level.

The pivot will receive :(a) A special slope rule alidade, with an index for read

ing angles on the protractor.,

{b) A special slope rule alidade with a luminous wire,for use at night.(c) A special alidade for night use, which is electrically

lighted.(d) A field glass support for the service glass, with an

index for reading angles on the protractor.



— 262 —

The sighting circle may be solidly mounted on a woodenframe or on masonry in an observation post. It can alsobe mounted on a plane table tripod.

Sitogoniometer, Model 1911.

550. The sitogoniometer, intended primarily for thelight artillery, is a pocket instrument for rapid approximatemeasurements during a reconnaissance, or at any timewhen more accurate instruments are not available.

It is used for :(a) Measuring the site, and determining the minimum

range which will clear the mask.(b) Measuring angles in mils and transforming them

into terms of plateau and drum.Consequently, it is sufficient for the rapid preparationof fire in indirect laying.

The instrument is contained in an aluminum case. Onone face there is a table of parallaxes. A handle isprovided, which also serves as a point of attachment fora cord.

551. To measure the site and find the minimum range.

*— (a) Site. — Hold the instrument edge to the front at theheight of the eye, in such a manner as to see the site bubbleand also external objects on the right side. Incline the

- i

'-i

—2 ~ 50=—1

instrument to the front or rear so as to center the bubble.Read the graduation seen at the height of the objective.

(b) Minimum range. — At the gun position, again holdthe instrument as if to measure a site. Select a point A onthe mask of the same site as the objective. Move theinstrument so this point is seen to the left. Bring the 0 ofthe scale to the height of the point selected, and read the

minimum range at the summit of the mask, 1800 as in(fig. 81)(*).

(*) This can only be used for distances from the mask notgreater than 300 meters and with the normal charge.



— 263 —

To measure angles and deflections. — Hold the instrument horizontally edge to the front close to the right eye,so as to see the deflection scales (*) and at the same timedistant objects over or under the instrument.

Bring one or the other of the indices at PI. 0 (**) on

the objective, the lower one if the aiming point is on the

Objective.Deflection : PI. {,, Dr. 120.

Deflection : PI. 12, Dr. i5o.

FIG. 8 3 .

right of the objective, and the upper one if the aimingpoint is on the left of the objective. The deflection isthen read at the aiming point, in terms of plateau anddrum.

If an angle is to be measured, look over the upper edgeand use the encircled figures with the 0 on the left.

Care oi instruments.

552. The following should be observed in the care ofi n s t rum en t s :

a) Keep in as dry a place as possible.b) W hen an ins t rument comes in wet, wipe it off care

fully before putting it aw ay .(c) Do not subject an i n s t rum en t to shock. Do no t use

force with it.d) Cleaning sho uld be l imited to the exter ior . In cleaning

a lens, do no t use cloth or other mater ial which can grease

(*) The total length of the scale is exactly 533 mils, 1/3 of aquadrant.

(*•) These indiros aro so marked as to make them easilyrecognizable.



— 264 —

or scratch. Breathe on the surface and wipe it lightlywith a piece of fine dry linen. Repeat this process untilthe moist surfaces has a smooth dull appearance, andevaporates regularly and concentrically.

(e) In handling theodolites, do not touch the scales with

the fingers. When wet, remove the moisture with a pieceof clean dry fine linen, lightly oiled, without rubbing.Remove dust without rubbing.

(/) It is strictly forbidden to clean, adjust, or dismountthe interior of instrument, unless specificallv authorizedby regulations. Instruments out of order should be sentin for repair.



PART V.

M E T H O D S O F F I R E

APPENDIX 13.

Sight Adjustment. — Calibration.

5i>3. Sight adjustment. — The laying instruments ofthe base piece are usually taken as reference instruments(instruments de reference).

The object of the sight adjustment is to compare theinstruments of the other pieces with the reference in

struments.554. Quadrant. — Lay the piece in question successively

at the elevations 0° 30 ', 1° 30'..., n° 30'. For each positionof the piece, measure accurately the elevation a with thereference quadrant, and the elevation a' with the quadrantof the piece used.

The differences a' — a can then be used to form a tableof corrections to be applied to the various elevations used

by the base piece to eliminate differences due to thequadrants (par. 196).If the piece is calibrated, these corrections are included

in the calibration corrections (par. 556).

655. Sight. — Lay the piece for direction successivelyat the following deflections :

7 5 . MILS. GI\AI>KS.

PI. Dr.0 100 50 50

2 100 150 150

4 100 250 250

14 100 6350 3950

For each position of the piece, measure accurately thedeflection b with the reference sight, and the deflection b'

with the sight of the piece used.The differences b' — b can then be used to form a table

of corrections to be applied to the various deflectionsannounced to the base piece (par. 191), in order to eliminatedifferences due to the sights.



— 266 —

556. Calibration. — The object of calibration is todetermine the individual elevation corrections to be appliedto pieces other than the base piece, so as to obtain uniformresults in range (par. 196).

Calibration in practice does not entirely achieve thisobject, but nevertheless is decidedly advantageous.

The calibration correction (correction de regimage) varieswith the range (*) and from time to time. It should bedetermined about every 1500 or 2000 rounds for the smallcalibers; about every 1000 rounds for the medium calibers.It should also be determined for as many ranges as possible,at least at 3000 and 6000 meters for the small calibers,and 5000 and 10000 for the large calibers.

Select a clearly visible and accurately known pointnear the middle of the field of fire, and at a suitablerange (•*).

Fire for improvement on this point with at least12 rounds per piece. Current precision fire should beutilized as far as practicable for this, purpose.

Four adjusted elevations are thus obtained for thesame objective, a, (reference piece), ab a^ and a4. Thecalibration corrections for the pieces other than tie reference piece are then :

These and similar results for other ranges are the meansof preparing a table of corrections for each piece otherthan the reference piece. The chief of section appliesthese corrections to the announced elevation.

(•) It may be taken that the calibration correction is applicable,whatever the powder lot used, for ranges within 3/4 or 4/3 of therange for which the determination was made.

(*•) The point should be located by intersection from at least 3te r res t r ia l observation posts.



APPENDIX 14.

Stripping an. adjustment.

Definition of the coefficient Ko.

557. The object of stripping an adjustment (par. 281)is to obtain information which will facilitate to the greatest possible extent subsequent firing with the same powder lot.

Stripping is based on the following considerations :

Let A be the map range of an objective, which for thisdiscussion is accurately plotted on the battle map.

At the instant of firing, a certain number of disturbinginfluences act to alter the normal trajectory of the firingtables, so that the ballistic range (distance ballistique) Dis different than the map range A. The ballistic range isobtained by fire for adjustment.

The difference D — A = M is the total correction to

be applied to the map range to offset the disturbinginfluences.Among the influences measured by M are some which

are known, and can be evaluated. Let M ' be the correctionfor these known influences. It is evident then that Ifthe fire be opened, not with the map range A, but withthe range D' — A + M', that is, with the map rangecorrected as far as practicable, the initial range will beless erroneous and the adjustment simplified.

This is in general the method actually used.

55S. The adjustment gives the ballistic range

D = A + M

From both sides of this equation subtrac t the correctionsM' for known influences. Then

D — M ' - A + M — M 'D — M' is called the stripped range. The equation

may also be written

D — M' M - M'

_____ _ i + _ _ _ _ _ _, Ko

M — M', from discussion, represents the incompleteness

of the evaluation of the disturbing influences for therange A. Its value is unknown, but, from our generalknowledge of the nature of such influences, it is evidentthat it increases with the range.



— 268 —

569. Experience shows that the difference M— M' isproportional to A, on condition that :

The same powder lot is used.The ranges considered do not differ too much

from A, or more specifically, if thev are within3/4 to 4/3 of A (par. 564).

]y[ jy j /

Therefore the ratio — is constant, which makes Ko.A.

constant also, under the conditions stated.560. Stripping an elevation or range consists practically

then in finding the coefficient Ko, for the powder lot used.This is done by stripping the ballistic range D of thecorrections M' for the known influences, and dividing

this range, D — M', by the map range A.561. Having found Ko, the ballistic range D,, for a newobjective whose map range is A,, can readily be found.

If M[ is the correction for the known influences affectingthe fire on the new objective, by the value previouslystated for Ko

P i — M ; K

A, = K o

that is, 1\= KoA, + M,Thus the map range A, is modified by multiplying it

by Ko, and correcting this modified range for the knowndisturbing influences MJ. This gives the corrected range(par. 192).

562. Because the value of Ko is only approximate, thecorrected range will not in general be found exact . It ishowever much more accurate than if Ko were not used,

which justifies the use of the method.

Meaning of K o.

563. Thus far, K o has been considered as an abstractquantity, without physical significance. The variousinfluences entering into it have not been dwelt upon.

These are :

Site of the objective.Wind.Air density .Weight of projectile.Quickness of the powder lot.Powder temperature.Wear of the piece.

Certain of these influences can be accurately evaluated,

such as the site of the objective and the weight of projectile/. Others can be evaluated only approximately,such as the wind and air density. Others cannot beevaluated, such as the quickness of the powder lot andthe wear of the piece.



— 269 —

Ko covers the incompleteness of the evaluation of theseinfluences (par. 558).

This incomplete evaluation consists of two parts :Errors in evaluating the known influences.Influences not known and not evaluated.

The first part is slight and negligible in comparisonwith the second. The term M — M' in the value of Koconsists for practical purposes of the second part . Fromparagraph 560 it is thus seen that Ko depends on thepowder lot and the piece used (*).

564. The quickness of the powder lot and the wearof the piece have influences which may be measured bya variation in muzzle velocity. The value M — M ' may

therefore be expressed by a range correction m due to thevelocity variation.Then

Therefore the assumption that Ko is constant holdsonly within such limits of map range that m/A is sensiblyconstant.

These limits can be found by trial, using the firingtables. Assuming a map range A and a correction inthis range of m, the corresponding variation in muzzlevelocity can be calculated. Using the same variation inmuzzle velocity, the range correction m^ can be found fora different map range K v

By continuing this process, it will be found that theratio nt/A, and consequently Ko, is constant only for

values of Ax between 3/4 and 4/3 of A (par. 292).

Method by using the velocity correction, V—Vo.

566. The restrictions on the use of the coefficient K ocan be avoided. Referring again to the equations ofparagraph 558, let

D ' = A + M' be the corrected range (par. 192)for the first firing, only the knowninfluences being corrected for,and

D = A + M be the range corresponding to theadjusted elevation.

Then D — D' = M — M' = m (par. 564).The correction m corresponds, for practical purposes,

to the total variation of muzzle velocity due to the powder

lot and the condition of the piece for the range A. The

(*) Calibration firing corrects for difference between individualpieces. Reference here i.s to the failure of the reference piece toconform to the firing tablus, due to irregularities in the piece itself.



APPENDIX 15.

Chart for time fire behind crests.

567. Use. — Calculate from tho battle map the slope nin percent (par. '21) of the ground to be covered.

Find from the firing tables the angles of fall w and theremaining velocity V,. for the range to be used.

For example, to cover a slope of 9 %, when :

i.) = 25°V,. = 300 m.

Read on the line (1), opposite the slope in percent, theslope in angular units, E (5° opposite 9 %).

Draw a line from the point 9 % on (1) through thepoint on (2) w — J (25° —5°) .

Join the point where this line intersects (3) with thepoint on (5) for the remaining velocity (300 in.).

At the point where the line last drawn cuts (4), read thenearest value of the ratio H/E. H is the range boundin meters, and E the corresponding fuse bound in seconds.In this case

H _ 100E ~ ~. 1

The ratio H/E means that to maintain the burst on a

line parallel to the ground, the fuse setting should beincreased (*) .1 sec. for each increase of range of 100 meters.These particular values need not necessarily be used, butthe two values should be in this ratio . The range boundis based on the usual considerations (pars. 263 and 264).

To find the actual range bound on the ground, join thepoint for w (25°) on the red graduation of (2) to the pointpreviously found on (3), and prolong this line to intersect(4).

Read on the red graduation of ('*) the ratio B (1.2.">) ofthe range bound on the ground to that on the horizontal.A range bound of 100 meters thus corresponds to 125 meterson the ground.

(*) If {the corrector is used, the fuse sotting is increased bydecreasing the corrector.



APPENDIX 16.

Adjustment by high air bursts.

568. Object. — By this method, objectives hidden fromterrestrial observation may be attacked with zone fire(par. 259), without aerial observation. The objective mustbe accurately located on the battle map.

The method may be used by day or night. It is easierand more accurate at night.

Fire for effect may be percussion or time.

569. Method. — A series of high air bursts, fired withthe same data by the base piece of a battery , are accuratelylocated by intersection from several observation posts.The changes in firing data necessary to bring the trajectoryon the objective can be deduced from these observations.

570. Adjustment by this method is a function of the

flash ranging groups.The artillery commander assigns the adjustmentsnecessary to appropriate groups, and establishes the orderof priority for each group.

Each group is furnished the coordinates of the base pieceof each battery for which it may have to make adjustm ents.These should not be communicated by telephone.

Permanence of telephone communication .is essentialto the success of the method.

671. The operations by the battery and the flashranging group are as follows :

The battery commander causes the base piece to be laidon the objective and forms the sheaf.

The officer in charge of the flash ranging has a trajectorychart (abaque de trajectoire) showing the trajectories forall elevations. He locates the objective on this chart byits range and altitude with respect to the base piece.

The fuse setting is determined from the chart so as togive bursts of sufficient height to be surely visible.

The elevation and fuse setting are transmitted to thebattery commander, who corrects them for the conditionsof the moment, and fires a series of 10 or 12 shots fromthe base piece, at the rate of 1 shot per minute.

The bursts are observed from three observation posts.One observer in each post measures the Y-azimuth of the

bursts by means of the reticule of his instrument, whichhas previously been set in a known direction. A secondobserver in two of the posts measures instrumentally thesite of the bursts.

The observaions are se.it to the central flash ranging



APPENDIX 17 .

S ound R ang ing - (Reglage par le son).

576. Sound ranging should be used by heavy artilleryin adjusting its fire, when conditions are suitab le and whenaerial or terrestrial observation is impracticable (*).

Experience has shown that, under suitable conditions,this method gives results which compare favorably with

those by the other methods.577. Objectives. — sound ranging is generally used inattacking hostile batteries previously located by the soundranging group which is to conduct the adjustment. Theadjustment is undertaken as soon as the battery is againfound to be active.

If the adjustment is undertaken at once after the ba ttery is discovered for the first time, there is a certain delay

between the location of the objective and the adjustment.The accuracy of the adjustment is less certain under thesecircumstances.

The use of sound ranging for adjusting on an objectiveknown only by its coordinates is much less accurate thanwhen the objective has been located by sound ranging, andshould be resorted to only when atmospheric conditionsare especially favorable.

578. Sound ranging requires the use of shells of largeexplosive capacity, and its application is therefore limitedprincipally to calibers of 155 mm. and above.% The 120 maybe used when conditions are very favorable.

The long shell is the most suitable, but the semi-steelshell can also be used. Instantaneous or non-delay fusesshould be used (**).

579. The fire must be carefully prepared, in order

that large changes will not be necessary.580. Conditions for use. — An excessive artilleryactivity, either friendly or hostile, can hamper the useof sound ranging or prevent it entirely (***).

Stab ility of atmospheric conditions is essential. An

(*) At night or on a dark day, or when the objective is hidden.(•*) IA fuses are not used, for, although they are favorable for

adjustment, their trajectory is altered when otherjfcfuses aresubstituted in fire for effect.(•••) If conditions warrant, friendly artillery activity may be

stopped, in order to permit an important sound ranging adjustment.



— 275 —

adjustment should not be undertaken if the wind velocityis over 5 meters, or if changes in atmospheric conditionsduring the adjustment are expected.

It is only by careful examination of the conditions ofthe moment that the advisability of undertaking an

adjustment can be determined. Decision on this pointshould be based on the advice of the sound ranging officerin charge, who should also decide when the adjustmentshould begin.

581. Telephone communication. — Continuous andsatisfactory telephone communication is essential throughout the adjustment.

582. Preliminary arrangements. — In the normal case

of a hostile battery previously located by sound ranging,the adjustment should be undertaken as soon as possibleafter the battery is again discovered in action. Theadjustment should proceed as rapidly as possible.

This end can be attained only when the sound ranginggroups and" the batteries to fire are held constantly inreadiness to undertake the adjustments contemplated.

583. Programs of adjustments. — The artillery com

mander of the sector accordingly draws up a program ofadjustments.

The objectives for which sound ranging is to be used inadjustment are indicated. Batteries are assigned to fireon these objectives, which the sound ranging groups haveordinarily already located.

The objectives covered by the program are in two classes:(a) Those to be attacked immediately upon call by the

sound ranging group concerned.(b) Those upon which fire can be opened only after first

obtaining authority.The program thus avoids delays due to consulting higher

commanders when quick action is necessary.The program is communicated to the sound ranging

group.

584. The sound ranging-group prepares charts for theadjustment beforehand. It gets in touch with the batteries with which it is to work, as shown by the program, andarranges for prompt and reliable telephone communication.

The artillery commander of the sector causes practiceexercises to be held to assure the smooth operation of thesearrangements.

685. Method of fire. — In adjusting by sound ranging,the method by measured deviations is used (*).

The adjustment is by piece.

(*) The operations of the sound ranging group require a considerable time. The different series cannot therefore be consideredas having been fired under the same conditions, and the usualmethod (par. .228) is not applicaMo.



— 276 —

The battery fires by successive salvos. The soundranging group determines the range and deflection deviations for each piece, and reports them to the b attery.

-The

changes are made for each piece, based on the center of theshots fired by each.

On account of the delay incident to the location of shots,the adjustm ent is carried only td a point which will enablethe data suitable in fire for effect to be calculated. Thesedata are then modified and verified during fire for effectwithout interrupting the fire.

586. Fire for adjustment. — The sound ranging groupuses only one adjusting point in locating the shots, evenwhen the fire is distributed (*).

The sound ranging group notifies the battery when it isready. The fire is delivered at a suitable rate, the soundranging group being notified of the number of each piece asit is discharged.

When the record is imperfect, the sound ranging groupsmay call for additional rounds from a particular piece, orseveral pieces.

The deviations are reported to the battery in range(meters) and in deflection (meters or angular units).

The salvos are usually fired at 10 seconds interval, andthe interval between the salvos of a series is about 2 minutes.

687. The firing data having been carefully calculatedfor the conditions of the moment, the battery fires a seriesof 2 salvos (**).

The sound ranging group reports the center of the twoshots fired by each piece, with respect to the adjusting

point (***). The ba ttery makes the necessary changes.688. The ba ttery then fires 3 salvos, which are reportedas previously and the necessary changes made, basedwholly on this series.

689. Fire for effect. — The data determined as a resultof fire for adjustment are used in fire for effect at a singlerange (****).

(•) When the fire is distributed, the battery should notify thesound ranging group, so that the latter will not be surprised atthe sizejof the deflection deviations.

(**) If the objective has a narrow front, the sheaf may beconverged for adjustment and opened in passing tofire for effect.If the pieces of the hostile battery are considerably separated,the fire should be distributed from the start so as to adjust eachpiece on its appropriate objective. To this end, the sound ranginggroup supplies a sketch showing the hostile battery as it has been

located and also the adjusting point chosen.(**•) If the battery so requests, the sound ranging group reportsthe deviations for all shots. Abnormal shots are always reported.

(****) It should be possible ordinarily to begin fire for effect aboutone hour after the hostile battery is reported in action by thesound ranging group.



— 277 —

3 salvos are first fired in the way of verification at theusual rate (*), followed at once by volleys for effect.

As soon as the results of the first three salvos are reportedany necessary changes are made, and the fire continued.

In order to verify the fire from time to time, salvos are

resumed and 3 fired at the usual ra te for adjustment. Thesound ranging group is given timely notice of this . Thefuses are changed it necessary.

If the successive variations show a regular change in theda ta, such changes can be predicted for the succeeding fireup to the next verification (**).

590. Use of the witness point. — It may happen that,during a protracted fire for effect, the conditions may

become unfavorable for further use of sound ranging.It is well therefore to adopt measures to reta in the advantages of the adjustment as far as it has been carried . Thiscan be done by firing on a witness point with terrestrialobservation during the intervals when the sound ranginggroup is working out its observations. Or the method bynigh air bursts may be used (par. 574).

691. Rem arks. — If the sound ranging group reports

that its records are not satisfactory, or that the shots arebecoming irregular, the firing is discontinued (***).592. If, during the firing, a par ticular piece g ives

abnormal deviations, this piece ceases firing, and the adjustment proceeds without it.

693. A comparison of the centers for the various piecesin a particu lar series affords a very accurate means ofdetermining the calibration corrections (par. 556).

Conversely, an accurate knowledge of the calibrationcorrections will materially simplify the adjustm ent bysound ranging.

(*) If fire for effect calls for delay fuses, these are not useduntil after this series.

(**) In this manner the fire for effect will be more continuouslyefficient under the constantly varying conditions.

(•**) The adjustment should likewise be given up if the windincreases to over 5 meters.



APPENDIX 18.

Percussion adjustment by FlashRanging- Groups.

694. The flash ranging groups (S. R. O. T. — Sectionsde recherche de renseignements par observation terrestre) should be utilized by batteries for percussion fire foradjustment, whenever the battery dispositions do notafford sufficient accuracy and when aerial observation is

impracticable.595. Objectives. — Ordinarily the flash ranging groups

are used for percussion precision adjustments on slightlydefiladed objectives, such as :

(a) Hostile batteries located by intersection on flashes(flammes) (*) or smoke.

(b) Objectives which are not visible with terrestrialobservation bu t whose location is accurately known. The

organization of the flash ranging groups is such that theobservers can set their instruments accurately (**) on aknown point even though it is invisible.

696. The defilade of the objective cannot be too great,or else the effect of the burst will not be sufficientlyvisible for accurate intersection . The permissible defiladedepends on the size of the burst, that is, on the kind andcaliber of the amm unition used.

697. The method is very accurate when the flash ranging group has actually seen the objective (***) or can see aknown point whose position with respect to the objectiveis accurately known.

The flash ranging groups should not be called on foradjustments on objectives which arc visible from the batteryobservation posts, except under very exceptional circumstances (****).

(*) The flash ranging groups cannot make accurate adjustmentson objectives located by the glare of their flashes (lueurs).

(**) This is generally not possible for the observation posts ofthe batteries, because of alack of a sufficiently precise organization.However, if there isa visible point near the objective whose positionwith respect to the objective is_ accurately known (by aerialphotograph or otherwise) the adjustment may be made on thispoint by the usual joint observation (observation conjuguee)

The flash ranging group need not be called upon in this case.(***) For the measurements of the observers are simply deviations with respect to lines which are known to pass through theobjective. All topographic errors are thus eliminated.

(•**•) Unless for practice.



— 279 —

598. Firing battery. — The method can be used by allcalibers. Calibers of 120 and under should use long shells.Instantaneous or non-delay fuses are used ordinarily. Thelong fuses are used only when they must be used in fire foreffect;

The preparation of fire must be executed with greatcare, in order to abbreviate the adjustment.599. Conditions governing the use of the method. —

An adjustment should not be undertaken unless theconditions for observation are satisfactory.

General artillery activity does not necessarily constitutea serious hindrance, unless the firing of other batteries onthe same or a nearby objective causes confusion of observations (*).

The wind can lessen the precision of the adjustmentwhen the defilade is sufficient to hide all but the smoke ofthe burst. The larger the bu rst, the less accurate are theintersections.

The method can be used at night, but the objective canbe only slightly defiladed, and instantaneous fuses mustbe used. If the objective is considerably defiladed, thefiring must at first be on some point near the objective

on which observation is easy (**), and whose position withrespect to the objective is accurately known.Since the success of an adjustment depends largely

on the conditions under which it is undertaken, it shouldbe begun only on the advice of the officer charged with theflash ranging. This ofl.cer notifies the battery when conditions are favorable.

600. Telephone communication. — Uninterrupted tele

phone communication between the battery and the flashranging group is indispensable for a prompt and satisfactoryadjustment.

601. Preliminary arrangements. Program of adjustments. — The batteries and the corresponding flash ranginggroups must be in constant readiness to undertake withoutdelay any task that may be assigned to them.

For this reason, the artillery commander in each sector

draws up a program of adjustments involving the use ofthe flash ranging groups. The la tte r are consulted in thepreparation of this program.

This program distributes the objectives to be attackedamong the various batteries (***). It also designates the

(*) In such a case, the artillery comm ander may interrup t ordivert the fire of certain batteries; if not, the adjustment must be

given up.(**) The same method may be necessary in the day tim e, ifobservation is difficult in the immediate vicinity of the objective.

(***) The flash ranging group prepares alis t of objectives whichit is prepared to adjust on. This list is used in preparing theprogram.



— 280 —

batteries to be called by the flash ranging groups in caseobjectives are located in various pa rts of the sector (*).

602. This program is communicated to the flash ranging groups, together with the coordinates of the batteriesto fire (**). The flash ranging groups make the necessary

preparations , and get in touch with the batteries withwhich they are to work (***). Careful arrangementsmust be made to insure satisfactory telephone communication. There should be complete understanding as tothe adjusting point, the kind of ammunition to be used,and the rate of fire.

Prac tice adjustm ents should be made frequently,with either simulated or actual firing.

• 603. The method. — The method is by measureddeviations (par. 228). The adjustment is by piece. Themethod of fire is by series of battery salvos.

The flash ranging group determines the center for eachpiece for each series of shots. The changes indicated aremade individually for each piece.

Rapidity of adjustment is essential for accuracy, inorder to avoid changes in the atmospheric^conditions.

The observation of the shots, their transmission to the

central station, and the necessary graphical constructionsconsume a considerable amount of time. It is thereforeessential that the adjustment be limited to the number ofrounds absolutely necessary in order to undertake firefor effect. This fire may be checked at intervals by theflash ranging group.

In this way, the adjustment of a battery of 4 piecesshould not require more than a half hour.

604. The adjustment. — The flash ranging group usesonly a single adjusting point (****), with respect to whichit measures all deviations.

(*) Among these are the so-called wandering pieces (piecesnomades) the use of which is becoming very frequent, and whichcan rarely be successfully attacked other than by this method.

(**) The coordinates of a firing battery should never be com

municated by telephone. In case of necessity only the Y-azimuthof the line of fire should be, given, or else the coordinates of anypoint on this line.

(***) The program furnished the flash ranging group shouldgive the habitual designation of the firing battery, and the telephone central to which it is connected.

(****) The adjusting point is chosen so that the shots of all pieceswill be in the field of view of the instrument when it is pointed onthis point. The individual deviations can then be measured bymeans of the reticule and errors due to backlash in the instrument

avoided. The adjusting point need not be visible. It may be.for example, a hostile piece whose flash has been seen.If the points on which the various pieces are adjusted are so

widely separated as to require the use of separate adjusting points,the pieces should be adjusted individually.



— 281 —

The battery communicates the time of flight to theflash ranging group.

The flash ranging group notifies the battery when it isready to observe The ba ttery fires at the rate previouslyagreed upon. The departure of each shot and the piecefiring it are announced in succession (%. When all ofthe shots of a series are not observed from 3 posts, additional shots are called for.

605. The deviations are announced to the battery indeflection and range. The former is in meters or angularunits, as desired by the ba ttery . The la tte r is in meters.

606. The rate of fire depends on the conditions ofobservation. This is the subject of agreem ent between

the flash ranging group and the bat tery . The rate agreedupon must not be exceeded, especially in salvos. Accurateintersections on shots are impossible if they are too closetogether. A regular ra te of fire greatly facilitates observation.

Under favorable conditions, a rate as great as 2 or3shots per minute can be used, both for a salvo and betweenthe salvos of a series.

607. The sheaf having been formed (either convergedor distributed) (**), the battery fires a series of 2 salvoswith suitable data and at the proper rate.

The flash ranging group determines the center for eachpiece, and reports to the battery the deflection and rangedeviations of each, with respect to the adjusting point (***).

608. The battery then fires 6 salvos with altered data .The flash ranging group reports the deviations of the centers as previously.

The data are accordingly modified, and fire for effect isundertaken.

If the first salvo of a series is lost, the series is begunanew at a different elevation. If one or several shots ofa piece are lost, the fire of this piece is completed a t theend of the series.

609. Fire for effect. — Fire for effect is by volleys at asingle elevati n, using the adjusted data . It shouldimmediately follow the adjustment. It should be deliveredrapidly, with no attempt to preserve a regular rate of fire.

(•) The departure of each shot must be accurately announced.(••) In adjusting on a hostile bat tery on a narrow front, the

fire should be converged, and distributed in fire for effect ifnecessary.

If the objective requires a wide distribution , the fire is distributed from the beginning of the adjustm ent. In this case, the flashranging group supplies a sketch of the objective, as located, withthe- adjusting point indicated.

(•**) If the parts of the objective are so widely separatedas to be considered as distinct objectives, select an adjusting pointfor each piece, and adjust each separately.



— 282 —

From time to time, the battery asks the flash ranginggroup to verify the fire for effect. For this purpose, salvosare resumed at the usual rate (the fuse being changed tothat suitable for adjustment if necessary), and a series of6 salvos fired. The deviations are reported, the firing datachanged by the amount of these deviations, and fire foreffect resumed at once.

610. In the cases where the adjustment is on a pointnear the objective (par. 599), the verification of the fire foreffect must be on this same point. As such fire is withouteffect on the objective, it should not be resorted to oftenerthan is absolutely necessary. In such cases, the verification can be made with one piece, and the others changedaccordingly.

If the successive verifications show a regular change, thenecessary modifications of data may be predicted andapplied progressively between verifications.

611. Adjustment of a single piece. — The adjustmentof a single piece should be undertaken only in the caseof large calibers, or rapid fire materiel for the attack ofa small objective.

A flash ranging group should not be called on for suchan adjustment, in the case of medium caliber slow firemateriel, as the small effect does not justify the timeconsumed.

612. As the lire is by single rounds, all shots can beobserved, both during adjustm ent and fire for effect. Theelevation can thus be continuously adjusted without interrupting the fire for effect.

The adjustment is by series of shots, the flash ranginggroup determining the center of each series.

613. The piece first fires a series of 2 shots, the centerof which is reported. W ith modified data, a second serieso-f 2 shots is fired.

The data are again modified based on the second series,and the fire continued by series of 6 shots . The modifications of data following each of these series are as follows :

1st series : Reported deviations.2nd series : One half of the reported deviations.3rd series : One third of the reported deviations (*).

614. When the change in data thus determined is lessthan one tabular range probable error and 2 mils in deflection, fire for effect may be begun w ithout continuous observation by the flash ranging group.

(*)SThe total changes made to include this series is the sameas if the piece had fired a single series of 18 shots. The method byaeries has the advan tage, however, tha t the shots are earlier broughtclose to the objective with an increased likelihood of producingsome effect.



— 283 —

If this result is not obtained with the 4th series of 6shots,discontinue the adjustment.

This method presupposes th a t the fire is conductedrapidly and that the atmospheric conditions are stable.

- If the fire is prolonged, it is verified from time to time asrequested by the batte ry . The verification is by series of6 successive sho ts.

615. Use of a witness point. — If an adjustment byflash ranging is not followed immediately by fire for effectthe batte ry should, on its own account, execute an adjustment on a witness point, real or fictitious (par. 293).

This is particularly important in active sectors where theflash ranging groups are continuously occupied.

616. Adjustment on a fictitious (fictif) datum point. —The usual method of adjusting on a datum point (par. 287)includes the selection of a clearly defined point on thebattle map and the execution of a complete adjustment(trial and improvement fire).

The center of a series of shots fired with the same data,when accurately located by the flash ranging group bycoordinates, constitutes both the datum point and theadjustment on it.

617. The method of using the flash ranging group inestablishing such a fictitious datum point is as follows :

One piece fires 12 shots at any suitable elevation, at therate agreed upon.

The flash ranging group finds the center, and reports itto the ba ttery by its coordinates. These coordinates arethose of the datum point, and the elevation used is theadjusted elevation (par. 219). The elevation must be

taken generally so as to place the shots where they can beproperly observed, and also in the vicinity of objectives inconnection with which the datum point is to be used.

618. On active fronts, it is essential that the flashranging groups devote their time to their principal missions,adjustments and the location of objectives. Under theseconditions, their use in observing fire on such datum pointsis exceptional.

On the other hand, during inactive periods, they shouldbe used for this purpose as often as possible. Practice isthus afforded, and ammunition is economized.

619. The rem arks (par. 591 et seq.) in the case of soundranging are applicable in the case of flash ranging.



LIST OF FRENCH AND ENGLISH TERMS

Abaque de trajectoire. . .A berceau trafneau. . . .A l'essaiA l'etudeA glissementAffut a echantignolles. . .

Alidade nivelatrice. . . .AmorcageAmor$age de c u l o t . . . .Amorcage instantane . . .Amorcage de tfiteAmorceAngle au niveau

Angle au niveau initial. .Angle du butAngle de chute

Angle d'arriveeAngle de direction . . . Angle de departAngle d'essaiAngle de hausseAngle d'incidenceAngle d'observation. . . .Angle de projection. . . .Angle de reglageAngle de relevement . . .Angle de surveillance . . .

Angle de t r a n s p o r t . . . .A

AppendicY. I : : : : : ! !Artillerie de renforcement.Artillerie de surete. . . .Artillerie de tranchee. . .

BarrageBarrage fixeBarrage semi-fixeBarrage roulantBarrage (Lever le) . . . .Beton

Trajectory chart.With cradle and sled.Under test.Being studied.Sliding mount.Mounted on wooden plat

form.Slope rule alidade.Fuse (in general).Base-fused.Instantaneous fuse.Point-fused.Primer.Quadrant angle of elevation

or elevation.Initial quadrant elevation.Elevation for the objective.Angle of impact (in some

firing tables translatedas angle of fall).

Angle of fall.Firing angle.Angle of departure.Trial elevation.Elevation.Angle of incidence.Observer displacement.Quadrantangleofdeparture.Adjusted elevation.Jump.Base angle.

Deflection change.APP end*> or supplement.Reinforcement artillery.Emergency artillery.Trench artillery.

Barrage.Fixed barrage.Semi-fixed barrage.Creeping" barrage.Lift the barrage.Concrete.



— 286 —

Beton armeBombeBouclier de gaineBranche ascendante. . . .Branche descendante . . .Bulletin de tirBut auxiliaireBut temoin

Cadence de tirCamoufletCanevas d'ensemble. . . .Canevas de tir, section de

— d'armee.

Canon courtCanon longC a n o n d e r e f e r e n c e . . . .

Carnet de batterie . . .Carnet d'observations. . .Carnet d'observatoire. . .

Carnet de pieceCartouche speciale . . .Causes perturbatrices . . .Cercle de viseeChangement des conditions

du tir.ChapeauChard'assaut(artilleried'as

eaut ou speciale).Champ de l'observateur. .Charge d'emploiCheminement d'angles. . .ClaieCloisonCoefficient de pente. . . .Coefficient balistique . . .Coefficient de reglage. . .CollimateurConditions du tirConduite du reglage. . . .ConsigneContre-penteContradictionConvergence des meridiens.Correcteur normal . . .

Reinforced concrete.Bomb (of trench mortars).Detonator protector.Ascending branch.Descending branch.Firing record.Datum point.Witness point.

Rate of fire.Camouflet.Triangulation system.Army topographical batta

lion (no exact equivalent

in our service).Howitzer.Gun.Witness piece, reference

piece.B C. data book.Observation sheet.Observation post data book

(O. P. data book).Section data book.Special booster cartridge.Disturbing influences.Sighting circle.Change in the firing condi

tions.Cap sill (of dugouts).Tank.

Field of the observer.Standard charge.Angle traverse.Screen.Lands (of the bore).Slope coefficient.Ballistic coefficient.Adjustment coefficient.Collimator.Firing conditions.Conduct of the adjustment.Standing or special orders.Reverse slope.Bracketing elevation.Convergence of the meridiansNormal corrector.

Correction de regimage . . Calibration correction.Correction de repartition . Distribution correction.Correction de station . . . Station correction.Correction complementaire Complementary site correc

de site . tion.



— 288 —

Elements aerologiques. . .Elements initiauxEn surveillanceEntonnoir deblaye . . . Equerre en zinc

Erreur de fermeture. . . .Escadron, chef d'Espace mortEventEvent initialExplosif tasseFaisceauFauchageFeuille de calculs

Fiche de renseignements. .FlecheFourchetteFourchette laterale . . . FuseeFusee a double effet. . . .Fusee fusante . . . . . . .Fusee percutante

Fusee detonateurGaineGainerelaisGaz toxiqueGaz lacrymogene

Gaz degage par l'explosion.GerbeGerbe de culotGerbe lateraleGerbe d'ogiveGisement .GlacisGoniometre

Goniometre boussole . . .

Goniometre de siege. . . .GradeGrossissementGroupe . .Groupement

HausseHauteur d'eclatement. . .Hauteur d'eclatement en

metres.Hauteur-type

Inclinaison. .Inclinaison des tourillons. .

Meteorological data.Initial data.On the base line.Clean crater.Map square.

Error of closure.Battalion commander.Dead space.Fuse setting.Initial fuse setting.Compressed explosive.Sheaf.Sweeping.Data sheet.

Information card.Maximum ordinate.Fork.Lateral fork.Fuse (proper).Combination fuse.Time fuse.Percussion fuse.

Detonating fuse.Booster casing.Booster.Lethal gas.Persistent or lachrymatory

(tear) gas.Shell gas.Shrapnel cone.Base sheaf.Lateral sheaf.Ogive sheaf.Y-azimuth.Forward slope.Angle-measuring instru

ment; also sight.Aiming circle.

Siege goniometer.Grade (angular unit).Power (of a telescope;.Battalion.Group.

Range setting.Height of burst.Linear height of burst.

Normal height of burst.

Inclination.Inclination of the trunnions.



— 289 —

Indice Index.Instrum ent directeur . . . Director.Instrum ent goniometrique. Goniometer.Instrument de reference. . Reference instrum ents.Intersection Intersection.Intervalle d'eclatement . . Burst interval.

Jalonne Staked out.Jumelles Field glasses.

Latitude Latitude.Lieutenant orienteur . . . Reconnaissance officer'.Ligne de projection. . . . Line of departure.Ligne d'observation. . . . Observing line.Ligne de site Line of si te .Ligne de tir Line of elevation.Longitude Longitude.Longue-vue binoculaire . . Scissors telescope.Longue-vue monoculaire. . Observation telescope.Lotissement Sorting (of projectiles).

Marron a lueurs Flash cartridge.Masse couvrante . . . . . Covering mass.

Masque Mask.^can i sme j M e t h o c L Methode jMeridien Meridian.Micrometre Micrometer, or reticule (of

a telescope).Millieme Mil (angular unit).Millieme R R-mil.

Millieme vrai True mil.Nivellement baroi^etrique. Leveling by barometer.Nord geographique . . . Geographic north.Nord Lambert Lam bert north or Y-line.Nord magnetique Magnetic north.

Observation axiale. . . . Axial observation.Observation combiner bila- Bilateral observation using

terale. the index method.Observation conjuguee. . . Bilateral observation usinga battle map.

Observation unil a te ra l . . Unilateral observation.Observatoire Observation post (O. P.).Observatoire de commande- Command observation post

ment. (C. O. P.).Observatoire de reglage . . Firing observation post (F .

O. P).Observatoire de reuseigne- Intelligence o b s e r v a t i o n

ments. post (I O. P.).Obus a charge arriere. . . Base charge shrapnel.Obus a gaz asphyxiant . . Gas shells.

ARTILLERY FIRING 19



— 290 —

Obus en ac ier Steel shell.Ob us allonge Lon g shell (0 . A.).Obus a bal les . Shrapnel (O. B.).Obus ecla irant Sta r shel l.Obus en fon te Cast iron shell (O. F.).

Obus en fonte acieree. . . Semi-steel shell (O. F. A.).Obus a m itrail le Case sh ot (O. M..).Obus de rup tu re Armor -p ie rc ingshe l l (A.P . ) .Obus de semi-ru ture . . . Semi-armor-piercing shell .Obus t rac eu r Trace r shel l.Officier or ie nt eu r R ec on na iss an ce officer.Origine de la t ra jectoire . . Origin of the t ra jec tory .Ouver tu re de la gerbe . . . Angle of opening .

Papier quadr i l le Squared pap er .Pa ra l l axe Pa ra l l ax .Pe nte arr iere Rev erse s lope.Piece directr ice . . . . . Base piece.P iec e guide-. B ase pie ce .Piece nom ade W and er ing piece.Piq uet reperes Stak es .Pla n meridien M eridian plane.

P l a nde

defilement. . .

Planeof

defilade.Plan d i rec teur . . . . . . B a t t l e map.Plan d'objectif . . . . . Object ive map.Plan de tir. Plane of fire.P lan de s i te Plane of s i t e .Planchet te car royee . . . Squared shee t .P l a n c h e t t e de tir Fir ing board .P lanche t t e topograph ique . Plane t ab le .P la teau P la teau .

Poids de la section droite . Sect ional densi ty .Poin t d 'a l ignement . . . Marker .Po in t de decl inaison. . . . DeelinaAing point.Po in t de chute Poin t of fall.Point moyen '. Center of impact.Point moyen du tir fusant . Burst center.Point de pointage Aiming point.Point de reglage Adjusting point.Point de repere Marker; reference point,Point de reperage Referring point.Point de surveillance . . . Base point.Pointage reciproque. . . . Reciprocal laying..Portee Range (of trajectory) (A. F.

§ 5).Portee entierement depouil- Completely stripped range.

lee.Portees par coordonnees. . Plotted.

Position de Crete Crest position.Position de grand defile- Position of deep defilade.

meat.Possibility's de tir Possibilities of fire.Posle de commandcmunt . Command post.



— 291 —

Poste d'observation auxi- Auxiliary observation post.liaire.

Preparation du tir . . . . Preparation of fire.Projectile Projectile.Projectile fumigene . . . Smoke shell.Projectile de reglage . . . Adjusting shell.

Quadrant Quadrant.

Rafale Volley.Rapporteur Protractor.Rapporteur de parallaxe. . Parallax protractor.Rayonnement Direction and distancemeth

od.

Rayonnement direct . . . Direction and distance method (directly).Rayonnement inverse. . . Direction and distance meth

od (inversely).Recoupement Resection.Rectangle de dispersion . . Rectangle of dispersion.Reduit Strong point.Regimage des canons . . . Calibration.Regime du canon Calibration errors of a piece.Reglage Adjustment.Reglage en direction. . . . Deflection adjustment.Reglage d'encadrement . . Bracket adjustment.Reglage fusant Time fire.Reglage fusant des obus ex- Time shell adjustm ent.

plosifs.R eg la g e percutant d'en- Percussion bracket adjust

cadrement. ment

Reglage percutant de preci- Percussion precision adjustsion. ment.

Reglage de precision . . . Precision or complete adjustment.

Reglage par le son. . . . Sound ranging.Regie a dessins ' . Straight edge.Regie a eclimetre . . . . Telescope alidade.Regie graduee Scale.Relais de feu Relay.Relevement Three-point method.Relevement non oriente . . U n o r i e n t e d three-point

method.Remblai Embankment.Repartition Distribution.Repere Marker.

Repere de position . . . Place mark.Reperagesurunbu ttem oin . Use of the witness point.Repgrer la piece Refer the piece.Reseau d'observatoire. . . Observer system .Retard Delay.



—

Rigidite de la trajectoire.Rose des ventsR u g u e u x

Sablier

Salve . . .Schem a des l i a i s o n s . . . .Section de recherche de ren

seignements par observat ion te r res t re .

Si togoniometreSom me t de la t ra jectoire . .Stat ion d 'or ientat ion . . .S urveillance , en . . .

Table de t ir TableauTambour Tir d 'an ean t issen ient . .T ir d 'am elio ra tion . . . Tir d 'accrochage

Tir de de stru ctio n. . . .Tir d'efficaciteTir d'efficacite fusant .Tir d 'encagement Tir d 'essai

T ir d ' in terd icti on . . . .Tir de harcelement . . Tir sur hausse unique . Tir sur but fugitif. . . .T ir de r ati ss ag e . . .Tir fusant d'obus a balles . Tir fusant en arr iere des

c re tes .

Tir de neu tralis atio n . . .Tir p longeantTir de precisionTir a r icochetT ir de reg im age . . .Tir de reglage . . .T ir de r ip os te . . . . .Tir de repre sailles . . .T i r sys temat ique . .

Tir tenduTir sur but suscept ible def T m o u v e m e n t .Tir sur zoneT ir su r b u t m obile . . . .

292 —

Rigidity of the trajectory. Wind rose, or wind chart . Fir ing pin.

Ground sill (of dugouts).

Salvo. Liaison system. Flash and sound ranginggroups .

Si togoniometer . Summit of the t ra jectory. Orient ing point . On the base l ine.

Fir ing table . Table (of figures).Drum. Annihilation fire.Improvement f i re . Fire for ad ju st m en t; used

specially in connection

with fire on a witnesspoint to designate theadjustment on the objec t ive .

Destruction fire.Fire for effect.-Time fire for effect.Box bar rage . Trial fire.

Interdiction fire.Harassing f ire. Fire at a single range. Fire on fleeting objective.Raking fire.Time shrapnel fire. Time fire behind crests,

Neutralizing fire.Curved fire.Precision fire.Ricochet fire.Calibration firing.Fire for adju stm ent .

R e p r i s a l f i r e .r

Systematic f ire.

Flat fire.Fire on a transient objec

t ive .Zone fire.Fire on a moving object ive.



—

Tir de-verification . . . Tir verticalTrajectoireTfajectoire dans le vide . .

Tranchee de depart. . . .Transport de tir

Travaux d'approche . .

Usure des pieces

Vent' balistique

Verification d/un angle auniveau.Verification des angles de

pointage.VisibUiteVingtiemeVitesse initiate • .Vitesse restanteVivacite

Zone battueZone des objectifsZone d'observation . . .Zone de securiteZone de surveillance. . . .Zone de dispersion en por

tee.

293 —

Testing fire.High angle fire.Trajectory.Trajectory in vacuo.

Assembly trench.Shifting fire or shift offire.

Works of approach.

Wear of the pieces.

Ballistic wind.

Verifying an elevation.Sight adjustment.

Visibility.Twentieth (of a degree).Muzzle velocity.Remaining velocity.Quickness (of a powder lot).

Pattern (of shrapnel).Objective zone.Observing sector.Safety zone:Sector.Range zone of dispersion,



ARTILLKRY ABBREVIATIONS

Art .A. A. A.

A. C. A.

A. G.A. D.A. L.A. L. C.

A. L. L.A. L. G. P.

A. L. T.

A. L. V. F .

D. G. A.

G. C. T . A-1

P. C.

P. 0 .R. n. A. L.

S. R. A.

S. R. L .

S. R. S.

S. R. 0 . T.

P. T. c. A.

T. P. s.T. S. F .

155 G 155 C

155 G155 G . P. F.

Artillorie.Artillerie anti-aerienne.

Artillerie de corps d'armee.

Artillerie de campagne.Artillerie divisionnaire.Artillerie lourde.Artillerie lourde courte.

Artillerielourdelongue.Artillerie lourde a

grande puissance.Artillerie lourde a trac

teurs.Artillerie lourde sur

voie ferree.Defense contre avions.

Groupe de canevas detir d'armee.

Poste de commande ment.

Poste observation.Reserve generate artil

lerie lourde.

Service de renseignements de l'artillerie.Section de reperage par

les lueurs.Section de reperage par

le son.Section de recherche de

renseignements par

l'observation terrestre.Section topographique

de corps d'armee.Telegraphie par le sol.Telegraphie sans fil.155 court.155 court Schneider.

155 court tir rapide.155 grande puissance

Filloux.

Artillery.Anti-aircraft artil

lery.Army Corps artil

lery.Field artillery.Division artillery.Heavy artillery.Heavy how itzers.

Heavy guns.High power heavy

artillery.Tractor heavy artil

lery.Railway ar t i l lery.

Anti-aircraf t defense.

Army topographicalsection.

Gommand post".

Observation post.(No equivalent or

g a n i z a t i o n " atpresent).

Art i l lery intel l i gence service.Flash ranginggroup.

Sound ranginggroup

F la s h a n d s o u n dranging groups.

Army Corps topographical section.

Earth telegraphy.Radio telegraphy.155 howitzer.155 Schneider how

itzer.

155 rapid firinghowi t ' / f*Y

155 high power Filloux.



— 296 —

o

o

o;i!

in

Hi

11

o

oo i l l }o S> «s S J ^CM

II



— 297 —



— 298 —

10

\ 0 \ CM

©

ooqo

ooob

f



— 299

O-oooq

ooo

- D

s

oooo



— 300 —

Various works and parts of a prepared terrain

Wire entanolements __

> TUrnout in a Communication trench

Steps to get In or out of a communication or fire trench'._ ,

CfOSsingiri a communication or fire trench

^Shelter

of Battalion

ot Re<j\rnent

Command Post of Brigade —

of Division

of- Army Corps..

Infantry obs ervaHon post A

[Occupied-

Artillery observation post \

i^rep

[Occup'iedine gun shelter

[Prepared- cf

Occupied—Emplacement for irench mortars

Prepared—

Cartridge . i.Munition depots. Grenades.

Trench en f net

Depot of tools and materials-

Subsistence depot

Water Supplies eg

stations



— 302 —

/Artillery

Croup in park t».!TI-tl

Emplacement , „_ Occupied Prepared

of Field Battery. , ^M \±ti

of Bakery 95. ± &

of BaH-ery loo. 4 O

of Baifery 1OS. §"..... .....&

of Battery ISO L.(/ong) * &

of Batten} 155L.Qonq) _ • °

of Battery JZOC. (short) * °

• of Battery 15SC. (short) • a

of Battery Z2O ® ©

of Battery Z?O • ©

of Battery 3?O & ®

Special types (*wM indication of , 1 , , 1

caliber in centimeters) ' 6

"f6

Antiaircraft station : ••» <=t>

Infantry munition section ^Artillery munition section ^ SM»

Section of park._ x S P

/Artillery park, army corps. (/€/ echelon) CD

Artillery park, army corps (Z&echehn) r i m

Echelon of main artillery park ^ ®

Echelon along the road. . ,(8),

When movable . -»vv

Intermediate depot (Heavy firti'l/ery)Dl

Pork (Heavy Artillery)



— 303

Engineers.

Company of Engineers

Searchlight section

Telegraph detachment of army corpsg y

Tklegraph section. (Army)~

Telegraph section of Z1^ line .

Fie,ld radio .station

Bridge equipage —

Army corps engineer park

Army engineer park

Medical Service

Ambulance ,

Hospital section

Group of sir etc her bearers.^——.

Evacuation hospital

•Section of evacuation hospital

Reserve personnel — _

Reserve, material.

Hospital m railroad station

Sanit&ry train.

•

•

%

A

^

r r o

(%$\

S J

@

(J)

/ T \

^



— 304 —

/Wiation

Squadron

Aviation park

A .Bombing group I

g a o l

Park of bombing group ij^ai

Landing field. y+

Captive balloon _ Q

Automobile Service

Section supplying fresh meat. 'u '

Sanitary section'automobile

Section fo r transportation or material 'u '

Section -for transportation of personnel [JT

Section of automobile park

Service of Administration and 5upply

Section of subsistence supply train

Section of auxiliary subsistence supply train

Cattle park ,

fir my field bakery

Miscellaneous

trainJ

Field remount depot _ &%,

Headquarters of advanced base beyond rail head: A



— 305 —

: 10,000

dcitwi

CITYT O W N

Commune

Hamlet

6O

30

20

FOREST „

WoodsWoodsWoodsWoods

CITYT O W NCommuneHamlet

andFOREST Over

Woods soWoods «W o o d s so

Woods &

CITYTOWN

C o m m u n e us

Hamlet

F O R E S T 45

WoodsWoods <

Woods

Woods

LARGE RIVER.

Brook, Pond

do

. . . .Jo.,

. . . d o . . . . .

. d o . to

. d o . 15

.dq..

LARGERIVER-so LARGE RIVER_

River. eo*>u River. zs*>Canal, Lake zombisCanal,Lake

Brook, PondVarious inscriptions

Bmok.Pond

e, chapel.cemetery.

Stimuli, sugar mill, brick'scrossing_to

d o . . . . . ... 'S

do 15

do.... . . . 15Defensive works

..do.

.do.

. d o .

JcNote:

arm,Hi/l 176.10

hes.izt,Miwl fire nvncnc9,cofnff>i

niufion freoc/Ki io^V o r k s It Si

•nbcn of iaffirttA

. „ i maps on scale of I hi ZO.OOO the.

conventional cartographic signs are robe the same at those on *he maps used

http://slidepdf.com/reader/full/...do...

http://slidepdf.com/reader/full/...do...



— 306 —

SCALE /-80.0O0 and Black JSO.OOQ French Maps

National Highway

Department roads

Sunken Elevated.

Always passable'-•—''-?•

yrepaired)

Wagon , Not always passable

Roads (irregularly repaired)

Dirr road and trail

Foot path

Forest pafh

A bandoned

. Single track. Standard gauge •< w »

c t i . Out ffflembankments

Tunnel VioJnct Culvert

Rai lways <Tunnel Viaduct

Grade Under Overhead

Road crossings

( IINarrow gauge and

Dummy /r'nes IIIIIIIIIIIHIWI

National

Department

BoundaryLine \ Arrondissement.

Canton

Com munc



— 307 —

SCALE /-80,000 and Black 1:5O.OOQ French Maps

Large River.

Creek

Intermittent Stream.

Cfltcacte.

Waterfall

Important navigable canal JUjjiiJ

Navigable canaldc/ / v *

Irrigation Ditch

Aqueduct optn

Ditch Dike

Hydrography*

La fee Pond

Poo// Reservoirt Cistern



— 308

SCALE /-80.0O0 and Black I-50.O00 French Maps

Church, steeple or belfry

use, harbor lights ~ *

Chapel or hermitage,

Oratory t important tomb

Crucifix, Cross

tomb, Statue of Virgin

Cemetery

Chateau or large house

Farm houie

Housi or isolated

Structure.

Beacon, chimney

Monument or tower

Works and JStructures \

Wind Mill

Mill (waterpotver).

Ironworks, factory{hydraulic power)

Factory

(nonhydraulic power) ~

Telegraph Semaphore

Cave, underground quarry,den, mine, shaft,entrance A> gallery

Lime - MiIn , plaster -A/'ln

Fountain, well, spring

Ruins



—¥309

SCALE t 8O.OOO and Black / =50,000 French Maps

Fences <

Geodetic .Points S

Stone .

Ditch

Bank

Hedge

Trees ..

Belfry, church, lighthouse

Chapel

Triangu/stion points*

Secondary points

Note:The figures which accompanythe symbols above, express inmeters the hight above thelevel Of Me sea

• P R E F E C T U R E

•» SO US -PR EF EC T.Classification of place names—

- CAJTTON

i» Comnrone



— •310 —

SCALE /-8O,OOO and Black /SO.OOO French Maps

Fortified City

Waited city and o/d fort

Works andStructures

Modern fort, batteryand intrenchment

Unprotected City

Village _

Woodland, deciduous, trees

Wood/and, evergreens

Brush



•— 311 —

SCALE / 60,000 end Black /-SO.OOO French Maps

Cultivated

Inundated.

Orchards.

Hedges and gardens.

LandClassification^

Peat bogs

Swamp.

Sa/t marsh.

Uncultivated landand cliff

Sand dunes and sand*&*&

'•'**£

Reefs above and underwa ter

Mountains



— 312 —

SCALE !• 200,000

Wagon

Roads

Railways

Hydrographic

g y dntSd

a/ways passableIrregularly maintainedpasSabifity uncertain

Dirt roac/S

/mporfent byroads.

Standard Gauge double

track I

Gaugetrack

Narrow 6aoge, framwrty

canal.

Large R'tver_

Note •The iso/gled bridges and

those serving the dirt roadsare the only ones shown

y-BridgeG-FordN-SkiffB-FerryTAerfa

A/arton.

Boundariesof

Department



— 313 —

SCALE f: 200,000 Colorof

Works and.Structures^

Classification„ ofPlace Names

Church in

Isolated church or chape'/

/mpor+ant Shrt'/te

Castle.

Observaiory toWer.

Ruin

Foresters />oi/se

Wind mi//

Water powerrttll/. sa*r milf—

Works, Factory

For tific a tions

E/evation Figures

Figures of population inthousands 0.7

'dry VILlt.VILLE.

Sma/J city, Market *>»n nTITE VILLE. BOt/fte.

Viffage, Commune, Fort Village .Commune. foit.

Mountain, forest, Laryeftr'ver— Montagne.Foril.neuve.

Ham/et,/mporfantRiver, Woods

Snail Mtn., Hill, Cliff, Peak

Glacier, Lake ___« /« . •« / • .



314 —

LEGEND FOR MAP OF SUPPLY SrSTEMOF FRENCH ARMY

Front

Limit of army sector-,

Limit and line of etape zone .

[ Standard gaugeStandard I Ration refilling point (with

gauge \ depot for reserve stores) _Rwy. I Station used as refilling point

1 without depot for reserve stores .

Animal trar.tinn I > I > I • 1 4

Mechanical traction

/mportant station

Secondary stationSecondary station with

Railway fe/ephone connection60cm.gauge

Siding (dead end). . rail dump

Unloading platform DR.

/mportant station withun/oading platform

fn far, try . Inf

Cava/ry Cav.

Horse drawn vehiclesand small ambu/ances, V.H.

Crossings dfor Heavy artillery with

indications of type A'A3B'83C'CL. A.L.G.P

7 ton trucks and Bufos V A.7

9 ton trucks and autos . V. A.3

10 ton trucks and autos . -V. A. 10

Road ballast dump.



— 315 —

LEGEND FOR MAP OF SUPPLY SYSTEMOF FRENCH ARMY

{

Artillery dump >&jL

Ammunition depot ijiAmmunition distribution tkcenter- c^.

Engineers < Engineerngineer dump — . I A I< • « "ark

^ Corps Engineer park \^J Lut

Medical-Hospital section (+JH 0 E

CJothing'depot I • 1

Slaughter house for army.

' Filling Station _Watering trough

Hospitals and CampsJEAU

Water

Supply for railroadsry and light

< Water supply depot

One way traffic .

State of the) Two way traffic

roads 1Three way traffic

LEGEND FOR MAP OFBOMBARDMENT OBJECTIVES

Aviation Parks from photographs ^ P

Aviation Parks from documents \ _ /

Railroad stations

Standard Gauge "to

Gauge "to

Gauge, location doubtful ,



— 316 —

LEGEND FOP MAP orENEMY HRST POSITIONS

77>e trenches and covered communicationsare indicated by green hatching

Dugouh, cellars anef inhabited houses.

Machine guns in the open

Machine guns under cover.

37mm. Gun

Observation post.

Trench mortar in the open.

o—*Trench mortar under cover

Distribution center .

Headquarters .

Concealed battery

Concealed battery in cas-emate

Emplacement, isolated

A n ti-aircraft gun

Ammunition depot .

Telephone fines, buried-

Telephone fines in the open



— 317 —

LEGEND FOR MAP OFENEM Y FIRST POSITIONS

Telephone exchange

Signal station (visual)

fiafion refilling por'nt, secondary

Ration refilling po/ht, pr/'ncipa/'__

Paths, means of approach

Crossings (important) of communicationtrenches and pa,tf>s , .,

Park, depor-of material-

Tunnel~ n i l

LEGEND FOP SKETCHES OFRESULTS OF DESTRUC TIVE Ff/fE

Targets com pletely destroyed

Targets possibly destroyed

Newly discovered

Aletv targets oArea covered by fire

Limits of area covered by photographs .



— 318 —

LEG EAID FOR ACTIVE HOSTILE BATTERYSHEET WITH DIRECTION OF FIRE

Caliber not determined O

F/e/tt ortillery, ca/ibeh 77mnrts.. CD

F/'elct artillery, ca/i&er /OSsnms.- earY/V/ery, c&/i6er /SO mms. o

Heavy artt'J/ery, ca/ihsr 2/O /nsnf and oven

Anti-aircraft section

Having already firedduring t-he preceding period .

Batteries Inactive during theseen to be preceding period butin action * tiaving fired previouscfuring the lo thatperiod ofC to

Ale*

Battery inactive during period to ^»_ but active during preceding period (_/

Q8 Emplacement known to be active duringthe period 28>

/

110 - Total number of emplacements /\\C\



— 319 —

LEGEND FOR DIACRAMATIC SCHEME OF

ENEMY OffQAN/ZATION

ON FRONT OF THE ARMY

Trenches with dugouts constructed

without concre te (o/d sty/e) * •*»>

Trenches with s/ia//oiv concretedugouts (new sty/e)

Positions (oM sty/e) with one or morereverse s/ope //>>«*

Positions (new sty/e) with one or morereverse s/ope lines

Topographic crest-,

Rai/ways, standard gauge, doub/e BLUl

ys. standard gauge, s/ng/e BlUC

Rai/ways, narrow gauge t I 11 111 111II11 I

Positions under construction

f FirstRoutes suitab/e for a// refy/c/esA(trucks and heavy arti//ery) ) SecondC/assed in order of exce//ence |

[ Third

Routes suitab/e for field upAeeparti/lery and field trains 1

/rregu/ar upkeep



— 320 —

LEGEND FOR GENERAL MAP OF

ARTILLERY OBJECTIVES

Observation post :

Munition depot, position unconfirmed

Munition depot, position confirmed

Bridge (wagon traffic)

Foot bridge _ _ _ _ .

Aviation Field, position unconfirmed

Aviation Field, position confirmed byphotography _ ^ _ — _ _ _ _

[ standard gauge.

Railway <I narrow gauge _

Co/lection of paths

Camp, Cantonmenf, Bivouac

Junction of roads or tracks (paths)

Telephone central

Signal Station (visual)

Artillery emplacement (active)

position from photographs ______Artillery emplacement (active)position otherwise determined —Artillery emplacement, prepared,position from photographs ______

Anti-aircraft gun ®

Dugouts -______-__——-. E__ ®>

Telephone line _____________________________ _ . ._ «i_.



— 321 —

GERMAN MAPS

Boundary

Lines

Roads

Pail Roads^



Fence

Hydrography*

Classificationof <

Place Names

— 322 —

GERMAN MAPS

1:25.000

Stone.-Steal bnidgt

Wooden. 6rid

Pontoon. C Z Z m m a w =

CaruxL .

Ghisf totun, of regency METZChifftouMv of district • THANN

Toton, SIEBJCK

Gorze

VUley* Noveant

HaaUet



— 323 —

GERMAN MAPS

1.25000

'•fr'f

£uerpreen> trees.

Mixed* ax>ocLr

LandClassification Bram hUs.Orier-pLoCt

• • ? • :

£

Dry



— 324 —

GERMAN MAPS 1:25.000:::^-:v^i

Wee Meadow

* . A

Land r/i i i i iunt4IIMUIIM

Was$ification< ViiiHiVni

(Yo p -ground, •

Garden, (plain).

ABBREVIATIONSStrctC,

ork,.

Small" Pond/- W.

/n/v

Wiascfi H.tittle. K U Big -(buy*) O n

Ob.

fir.—JIaus -ffrn— Heinx,. Bch*—B<xch

Jim Haxuen I Df~. Doff I B$. —Jtu/y



— 326 —

Miscellaneous

Symbols

GERMAN MAPS

1:25.000SIGNS

OiureA. •**•*

CkurcK mil/tout steeple?

-Kop..

WM..

WwUrrruU,-

Tnnnrsy LM.

Sote-miU/. .S.M..

Mtadout -keeper. .W.W..

CdurtU.

Observatory, Tower.

.A .



— 327 —

GERMAN MAPS

1:25.000SIGNS

Lone. Tree..

/mportcuU.

Mottusnsat,

Pit and, DitcA-

Miscellaneous

SymbolsRocks.

Jttoorh. c&rvLery

TarsnuU,

Fountain..

Or%erUing Post

Gr.

-€3

KhfL-

K.O.

T.O. .n

fort

Battery, .***



— 329 —

CONVENTIONAL SIGNS COMMONLY

USED ON GERMAN MAP8. Colorof

Symbol

3 7 cm. Revolver Gun.

S cm. Belgian Gun.

7 -7 cm. Fietd dun.

Anti-Aircraft Gun.

9 cm Field Gun.

10-5 em. Light Field Howttter.

K> em . Gun. (new er p«tterrv).

12 cm. Gun.

12 cm. Belgian Gun.

16 Cm. " Ringkanon*."

16 cm. Long Gun.

16 cm. Heavy Field Howitzer (13).

2i cm. Mortar (oM pattern).

21 cm. Mortar (newer pattern).

•0 mm. and 05 mmFrench Gun§.



— 330 —

CONVENTIONAL SIGNS COMMONLY

USED ON GERMAN MAPS. Colorof

Symbol

10 em . Gun (older p attern)

13 cm. Gun.

18 cm . Gun ( i .S. l_) .

16 cm . Russian Gun .

IS cm. Heavy FieldHowitzer (older pattern)

3 0 ' 5 cm Mortar.

or J " f l 42 cm. Mortar.

Barn

Brick-kiln

Telegraph detachment.

Field signalling detac h/nen l

Wireless telegraph station.

Bhf Bahnhof (Sta tion )

Hp. Haltepunkt (Stopping place)

Blst. Blockstallon (Block signal sta tion)

Lst La du telle (Loading platform).

b W Babnw arter (Plata layer's hut)

> MM > *co

ScA

BLACK

ED awe

A



CHART SHOWING LINES OF EQUAL MAGNETIC

DECLINATION

SsJ

\ /CHART SHOWING LINES OF EQUAL MAGNETIC DECLINATION, JULY 1 9 1 8 .

DOTE.

D e d i c a t i o n I S o w e s t .C h a r t m a y )>i< i s c d w i t l i u u t c o r r e c t i o n f o r t h e y g a r 1 9 1 8 w h e n d e c l i n a t i o n t o < / 3 d e c r e e I s d e s i r e d



INDEX

Paragraph!.

Al lSCISSAE 4 5 9

ADJUSTING.

—p o in t 20 7, 288—projecti les 10 0, 334Choice of a n —p o in t . 97

ADJUSTMENT.

—coefficient (See Ko)— by f lash ran gin g grou ps 571 A pp en dix 18—by high air burs ts Appendix 16— by measured dev iat ions 22 : . 394—with aer ia l observat ion 232—with shrapnel . 239 to 246—with terrestr ia l observat ion 231

Bracket— 203, 239 , 253 , 447Bracket — of a single piece in flash ranging 613

Conduct of the— 207Definition of fire for— 202Deflection— 208 t o 210, 230 to 232Fire for—in flash ranging 604Fire for—in sound ranging 586 to 588Gas shell— 276

Height of burst— 24 4, 359Percussion bracket— . . . 206 , 229 to 2 3 8 , 447Percussion precision— 206 to 228Program •!—in sound ranging 5 8 3 , 584Program of—in f lash ranging 6 0 1 , 602R a n g e — 2 1 1 to 214, 233 to 2 3 8 , 445Sight— 553 to 555St r ipp ing an a d ju s tm e n t 281 to 285

Time fire— 206, 239 to 252Time shell— 247 to 251Time shrapnel— 239 to 246

AERIAL OBSERVATION (See O bserv ation). 29 3, 297 , 573

AIMING CIRCLE.

Accuracy of— 126Declinated—in preparat ion of f i re without maps. . 169Description and use 517 to 530

Lighting device for— 522Locat ing po in t wi .h— 480 t o ' 490Special use with 75 14 8, 521To decl inate the— 525To determine the "¥ -azim uth of a l ine w ith th e— . . 527



— 335 —Paragrap h ! .

BALLOON. •Captive— 575

BAROMKTEB 197, 402Altitude by— 402, 491Leveling by— 495

BASE LINE (Pee Base piece).Definition 112Definition of "on the—" 142

BASE PIECE.Definition 112Establishing the—on the base line. . . . 144 to 153

BASE POINT.

Definition 112

BATTERY POSITIONS.

Reconnaissance of— 66 to 69Selection of— 53 to 69Suitable places for— 68 to 69

BATTLE MAP.

Colors used in— 457

De' nition 116Terms used in— 456 to 463Use of—in bilateral observation 443 to 444

BOMBS 304, 312

BOOSTER \ 306

—charge 306—casing 306Special—cartridge 306Detonating— 306

BRACKET 215

—on a crest 266Size of— 216, 234

BRACKET ADJUSTMENT 203

BURST—center 24

—error (See Probability).—interval 6—line of site 6—range 6, 100Altitude of— 6Effect of the individual— 346 to 380Height of— (See Height of burst).Influence of depth of—on eff ct 365OJ

servationof— 100 to 106

fh»af of— 345 o 350Use of low—in adjustment 250Use of high—in adjustm ent Appendix 16Variation of effect with position of—•. . . 355 .to 873



— 336 —Paragraph*.

B R A N C H .

A scend ing— ..—. .Descending—

CAL IBRAT ION

—correc t ion—firing

CAM OUFL AGE .

—of ba t te r ies—of observat ion posts

CAM OUFL E T

CASE SHOT.

Effect of burst of—FusesIncendiary effects with—Description -~.Zero fuse sett ing with—

CAST IRON SHELLS

Range of fragments of—Burst of—

C E N T E R

—of impact B u r s t—

CHARGE (See Powder}.

—in curved f ire for adjustmentChoice of—Effect of variation in weight of—

Sta n d a r d —C H A R T S .

—for time fire behind crest—for sound rangingSlope—for air bu rs tsTra jec tory—

C I R C L E .

Aiming— (See Aiming circle) . R a n g e —

C O E F F I C I E N T .

Adjustment— (See Ko). Ba ll ist ic —Ko (See Ko).Slope—V o (See V o ) .

COMMAND PO STS . *—of higher art i l lery unitsB a t t a l i o n —B a t t e r y —

77

556

554, 556564

6579 to 80

37$

374 to 380327380323376

. 302

350350

18

1824

22318 4, 18 8, 223

46

46

Appendix 15584

A pe nd ix 1 5 , 26.7571

181

1 0 , 406 to 408

21

838586



— 337 —Paragraph!.

Regimental— . 84Selection of— 81 to 87

CONCEALMENT.

—of batteries 65 , 68 . 69

CONDITIONS.Atmospheric—. 17

CONDITIONS OF FIRE (See Fire).

CO ND ITIO NS OF THE MOMENT 281

CONSTANT.

Declination— 117Deflection— 142

K o (See K o ) .V o (Pee V o ) .

COORDINATES.

—of an ob jectiv e 460Geographic— 458Hectometric— 460To measure— 501To plot a po int b y — 502 to 503Use and definition . 459 to 460

CORRECTION.

— and var iation differentiated 33—for curvature and rotat ion of the ear th . . . 42—for drift 188

- i n deflection for inclina tion of trunnio ns(Ap pend ix 3) 40

- in percuss ion precision fire for effect 254— in site 3 5 , 3 6 , 50

— in tim e fire. . . , 49 to 51Adjustment— 284aAtmospher ic— . . 43 , 44 , 51 , 192 , 396 to 404Ballistic— 45 to 4 8 , 5 1 , 396 to 404<Calibration— 554 , 556Classes of— 34Complementary site — 37 , 193 to 19 7tDeflection— 18 8/ , 191c, 283

Distribution— 189Individual— 20 9, 23 3, 254Individual—in initial dat a ' 1 9 1 , 196Range— 564Site— 193Stat ion— 183Topographic— 3 5 . 4 2 . 50Velocity—(See V o |W ind— 4 4 , 399 to 401

COUNTER BATTERY FIRE. I*9*'

Nor ma l front of ob jectiv e for— 207

CO UN TE R SLOPE . . 178

CO UP DB HACHE . 347



Paragraph*.

CRATER.

Clean— 36 8, 370Dim ensions of shell— 369

C R E S T .

— po sition : . . 60

Definition 55Height of burst adjustm ent on — 240Tim e fire for effect beh ind— . . . . 265 to 269 , 567

CURVE OF SECURITY.

Definition

CORRECTOR.

Normal—

D A T A .

Adjustment—Map—

Meteorological—(See Meteorological).

DATA SHEETS.

Definition

Special—for witness point

DATUM POINT .DefinitionDeterminRtion of—Use of—in shifting fireUse of fictitious—in flash ranging. . .

DEAD SP ACE

D E C A G R A D E

D E C I G R A D ED E C L I N A T I O N .

—constant

Magnetic—

DECLINATING POINT

DECLINATO R.

—for plane table

—for aiming circleDEF LECTIO N. '

13

1 b, 44

281177- 182

186

2'j , 298

. . . 253288

95, 291287 to 292616 to 618

59, 60

14

14

117

463

463

509, 510

518

— a dju stm en t . . . 208 to 2 10 , 230 to 2 32 ,440 to 44 1, 446

—bracket 208—constant 142— correction 188f, *191c, 283, 555—deviation in bilateral observation

— deviation in unilateral observation . .—difference—error -.—in error— in percussion zone fire for effect. . . .

449

437, 438156

452258 to 260

19




—in time fire for effect—mean e r ro r "—probable er ror Base—Correction in—

Corrections in—for inclination

DefinitionIni t ial—Recording the base—St r ipped—Str ipping for—

D E F I L A D E .

—of a bat tery—of trench ar t i l leryAerial—Calculation of—DefinitionDust—Flash—Height of bu rs t with— object ive

Plane of—Position of deep—R ec on na iss an ce of— .Terrestrial—

263 to 26419

2081 63 , 18 8, 286

188 to 189

of the t runnionsAppendix 3 , 40

142191163

283, 298v . . 2 83 , 298

". . 5567

64, 6556, 58

556362

240

556066

55 to 61

D E G R E E S .

DefinitionSixteenth of—Twentieth of—

141414

D E N S I T Y .

—of fire in percussion zone fire for effect—of fire with gas shell—of fire w ith sm oke shell

277 to257279280

A i r -Sectional—of projectiles

D E S T R U C T I O N F I R E .

—with gas shells . .D E V I A T I O N .

—in direct ion—in height of burst—in ransje

4310

272 to 2 7 3 , 27 5, 277 to 278

.' 99101100

Ad justm ent by m easu red— . . . 21 8, 22S , 58 5, 604Observat ion o f - (See U nilateral and Bilateral

ob serv ation ) 98 to 104

DIOPT E R 536

D I R E C T I O N .

D ete rm ina tio n of a 465 to 469Deviations in — 99



— 340 —

P»r»gnphi.

Observations in— (See Unilateral and Bilateralobservation) 99, 102

DIRECTOR.

Goniometer or plane table used as a— 144Parallel fire using the— . 155

To establish the—on the base line 147To establish the base piece on the base line with— . 148

DIRECT LAYING 165

DISPERSION 17 to 24

—in time fire 23, 24—on slopes 21Application of the laws of—to methods of fire.

Causes of—Projectiles affecting—

Range zone of—Rectangle of—Study of—Zone of—

DISPLACEMENT.

Observer—

DISTANCE.

Angular—

DISTRIBUTION.

—correction

DOUBLE DECIMETER SCALE

DRIFT

DROP

Appendix 2

1717

20, 21528

18 to 2423, 24

96, 433 to 438

16

189

503, 504

11

8

ECHELONMENT OF THE OBJECTIVE 1 7 8

ELEVATION.

—for the objective—in systematic fire •.

253261

Adjusted—. . . . 197 , 219 , 253 , 392, 439, 565Bracketing— 218Changing—during adjustment 286

DefinitionInitial—Initial quadrant—Quadrant—Trial—Verified—Verifying an—

EMPLACEMENTS.

4192 to 1 .5 , 234193

2215, 223, 391215, 337. 383

213

Characteristics of battery—. , 68 to 69Reconnaissance of battery— 66 to 67

ERROR (See also Probable error).

Deflection— 19



— 341 —

Paragraphs.

Deflection mean— 19Height— 19Height mean— 19Range— 19Range mean— 19

ERBOR OP CLOSURE 47S

EXPLOSIVE.

Percentage of—in shells 305

FALL.

Point of— 3

FIELD.

—of the observer 96—probable error 22

FIELD GLASSES 541

FIRE.

—at a single range 204—direction 101—for adjustment (See. Adjustment) 202—for effect (See below).

—with a witness point 297 to 30*—against woods 24SCalibration— 48, 564Conditions of— 1736, 184, 225 to 227Conduct of— 101Counter battery-—. (See Counter battery fire).Continuous— 255Cross— 231

Curved— 13, 223, 224, 340Destruction— (See Destruction fire).Faulty— . . 256Flat— 13, 339Harassing— 270, 572High angle— 13, 180, 224, 341Improvement— (See Improvement fire).Initial firing data—Interdiction—

Method of—Method of—in flash rangingMethod of—in sound rangingNeutralizing— (See Neutralizing fire).Parallel— (See Parallel fire).Percussion— (See Percussion fire).Plane of—Possibilities of—

Preparation of— (See Preparation).Ricochet— (See Ricochet).Shift of—Shifting— (See Shifting)Shrapnel— against aircraftSweeping— (See Sweeping Fire).

173 to 198270, 572

Part V603585

2, 230, 25859

253287325




Systematic— (See Systematic f ire) .Testing— 17 1, 286Time— (See Time Fire).Trial— (See Trial fire).Zone— (See Zone fire).

FIRE FOR EFF EC T 20 2, 25!) to 271— in flash ranging 609 to 610— in sound ranging 589— with aerial observ ation 255Classification 204 , 253Definition „ . 202Effec tiveness of— 258Gas Shell— 277 to 279Percussion precision— 253 to 25 6, 393

Percussion zone— 25 3, 257 to 261Systematic— 261Time— 25 3, 262 to 269Time— behind crests 26 5, 269Time shrap nel— 262 to 268Zone— 22 9, 270

FIRING BOARD 116, 496

FIRING PIN 310

FIRING T A B L E .

Cond itions on which based 29FLASH RANGING 57 1, 594 to 619

—groups 594A d ju stm e nt b y m easured d ev ia tion s in — . . . 604Fire for adju stm ent in— 604Fire for effect in— 60 9, 610Fu ses used in— 598M ethod of fire in— 603O bjectives in— 595 to 597Program of adju stm ent in— 601Shells used in— 598Telephone comm unication in— 600U se of fictitious datum point in— 616Use of the witness point in— 615W andering pieces in— 601

FORK.

— in im pro vem ent fire. . . 219 to 22 7, 439 to 441— in sy ste m ati c fire for effect 261— in trial fire 215 to 2 18 , 43 4, 437Definition 215L a t er a l - 4 3 1 , 434

FRIENDLY TROOPS.

Distance of gas shell ob jective s from— 386

Range in firing close to-— 234Time fire close to— 26 8, 269

F U S E S

— for H . E . Sells 306 to 320




—forshrapnel 327—used in flash ranging 598—used in percussion zone fire for effect 257—used in sound ranging 578Change of—during firing 227

Combination— 318 to 320Delay— 313 to 317Detonating— 305Influence of difference in— 227Instantaneous— 309, 310Instantaneous—effective against 310Non-delay— 311, 311Percussion— 308 to 317Time and combination— 318 to 320

FUSE SETTING.—in tim e fire adjustm ent. . . . . . . 239 to 252Adjusted— 239I n i t i a l - 197, 242, 245Zero—with shrapnel 37*

GAS.

—shell (See Oas shell).Shell— 351 to 354

GAS SHELL 272 to 279Ammunition consumption with— 277, 278Characteristics of— 383Density of fire with— 277 to 279Design of— 330Destruction fire with— 277 to 279Effect of atmospheric conditions on— 382Fire for effect with— 277 to 279Fire for adjustment with— 276Fuses for— 332, 333Kinds— 328, 329Lethal— 382, 383Marking of— 331 , 383Nature of effect of— 381Neutralizing fire with— 277 to 279

Persistence of— 382, 383, 385Persistent— 274, 277, 279, 329, 331Safety conditions with— 384 to 386Storage of— 387Telephone conversation in reference to firing— . . 386Use of— 382, 383

GONIOMETER.Definition 117

Siege— 142Sito— 550 to 551Use as a director l i to 153Use in establishing the base piece on the base line

l*o to 153



— 344 —Paragraphs.

GRADE . . 14HEIGHT.

Effective—with time shellDefinition

Deviation in—Linear—Normal— , . .Observation of—

HIGH EXPLOSIVE SHELL.

—in time fire for effectEffect of burst of—Fuses for—

Kinds—Penetration of—HUMIDITY.

Tabular relative—Jlygrom etric state

ILLUMINATION.

—error .—mean error

HEIGHT OF BURST.

—in time fire for effect—in fire for effect—in time behind crest—with defiladed objectiveAdjustment of—. .Adjustment of-»-by site change

1919

262244, 375

266240, 265, 269

244251247

6

10166, 240, 244, i62, 376

j . . 101

26%, 356 to 364346 to 373306 to 320

301 to 305338 to 373

43398

Measure of—in optical instruments 532INDEX.

—of a shotSignificance of the—

IMPROVEMENT FIRE.

—in unilateral observationAerial observation in—Conduct of—Definition

INCLINATION.—of the trajectory—of the trunnions—corrections for the trunnions

INFLUENCES.

Disturbing—INSTRUMENTS

Care of—. . . •Cleaning of—Declinated—Reference—Undeclinated—

445448

439 to 441220

219 to 224, 391203

74040

557Appendix 12

552552d465553466




Definition and use of— 14 to 15R-mil 14True— 14

MIRRO R.

Laying by— , . . . 163MORAL SUPPORT 199

MOTION.

Lim iting quan tity of— 13MUZZLE VELOCITY (See Velocity).

NEUT RALIZING FIRE 572— with gas shells . . . 272 , 274, 27 5, 277 to 279Object of— 19 9, 274, 275

NO -BU RS T 310, 339

N O RTH .Magnetic— 1J31, 463Lam bert— 116, 3&7, 408True or geographic— 458

O BJECTIV E.—in flash ranging 595 to 597

— in sound ranging 577 to 579—map 181—zone 181Coordinates of— 460Eche lonment of the — , 178Elevation for the— 253Fire on a moving— 165 , 25 3, 271Height of bu rst adjustment with defiladed—. . . 240Num erical designation of— 460

OBSERVATION Appendices 7 and 8, Par t III—in ad jus tment 206 to 252—of deviation 98 lo 102, 430 to 450—of direction 99—of fire 96 to 102— of the height of burs t 101—of the zone 10 7, 108—for range 100 to 104

—sheet 108—system 72Aerial— in ad justm ent 232 , 245Aerial—in fire for effect 255, 271Aerial—in improvised fire 220Bilateral— 106, 442 to 450 , 595Charac teristics of— 90Definition of term s used in— 96

Flank— 104Kinds of— 89La tera l— 104 to 106Method of— 90Objects 88Terres trial— 91 to 108, 231




Topographical operations preliminary to—. 93 to 95Un ilateral— 105, 430 to 441

OBSERVATION POST.— record .. . . . 109

Approach to— 79 to 80Auxiliary— 70, 75, 76Barrage batteries— 76Camouflage of— 78Classes of-— 70Command— ' . 70 , 72 , 916Construction of— 78— data book 94Firing— ;u , 73, 89 , 91c

Heavy artillery— 74Intelligence— , . . . 70 , 7 1 , 91aLocation of—in prepa ration of fire . . . 166 to 172Organization of— 91Reconnaissance of— 77 to 79Selection of— 77 to 80Terrestrial— 89

OBSERVER.

— displacement 96 , 433 to 438Field of tha— 96

OBSERVING.—sector 96— line 96 , 443

ORDINATE 459

Maximum— 1, 39

ORIENTING.— point 127 to 140— topographical ins tru m en ts. . . . 1 1 7 ,5 0 7 , 524

ORIENTING LINE.— through the base piece 138, 150 , 168Advantages of an— 451 to 455Definition of— 119a, 122Determination of an—. 125 to 129, 166, 169,

286, 422, 452 to 454Location of battery without— 151Selection of— 122 to 124Use of— 455W ithout preliminary determ ination of the— . . . 151

ORIGIN LINE.Definition of— 94Determ ination of— 94, 422

PARALLAX.Calculation of the— 159Definition of— 16Determination of the— 158 to 161Measurement of—on the map 160



— 348 —

Paragraph.

Measurement of—on the groundRemarks on the variation of—

P A R A L L E L F I R E .

— by reciprocal laying—using common aiming poinl

—using the director Establishment of—

P A T T E R N , O F S H R A P N E L

P E N E T R A T I O N

—in concreteP E R C U S S I O N .

—zone fire for effect

Corrections in—firePIECE (See Base piece).Errors in individual—in fire for effect.

Reference—Wear of—Wander ing—Witness—

PL ACE M ARK.Definition of—Determination o. '—Selection of—. . . . . . . . . .

P L A N E T A B L E .

Accuracy of—Definition ' . .

161159

162156

. . . 155. . . 154

374

338 to 345

345

257

35 to 48

191. 196, 2 3 3 ,256

48, 55622, 48

601297'

1196132

. . . . 130

126116

D ecim ated — in loca ting a po int . . . . 470 to 479

De clinated— in pre pa ratio n of fire w itho ut m ap s. 169Decl inator for— 509D esc riptio n an d use— 505 to 512O rie nt atio n and dec lination of—. . 11 7, 507 to 510Use is esta blish ing base piece on ba se lin e. 144, 153U se in loc atin g a po int 470 to 479

P O I N T .

—of fall (See Fall).

Datum—- (See Datum point) .Witness— (See Witness point ) .

P O S I T I O N S .

Bat te ry—(See Bat te ry ) .Tre nc h arti l lery— 67 :

P O S T S .

Command—(See Command posts) .Observat ion—(See Observat ion posts) .

POWDER (Sec Charge).

C han ge of— lot • . - . . • 225Class ifica tion of— 46N a tu re of— 46



— 349 —Paragnphi.

Quickness of— 46Temperature of— 47

PREPARATION OF FIRE Part IV—consists of 110

—in open warfare 165—in position warfare 165—without maps 164 to 172Care necessary in— 198Deliberate and rapid— 198, 216Definition of elements in— 116Object of— 110Topographical operations preliminary to—. I l l

118 to 140

PROBABILITY.

Probable error on slope 21, 184-J&ble 26Deflection probable error 19,. 208Determination of probable error 19Examples in— 27Field probable error 22Height of burst mean error 24Probable error on the ground 21Range of burst mean error 24Range probable error 19Tabular probable error 22

PROBABLE ERROR (See Probability).

PROJECTILE.

—affecting dispersion 17

Adjusting— 100Change in— 226Influence of weight of— 45Sorting of— 17

PROTRACTOR.

Celluloid— 499Description and use 451, 497Parallax— 181, 499

Tracing paper— 499White paper— 499

QUADRANT.

—adjustment 554—angle (See Angle).Definition 14Initial—elevation 193Laying by— 193, 284a

RADIO—stations 82—officer 424

RANGE.—adjustment 211 to 214, 233 to 238, 445—correction 564



— 850 —Pirkgnph

—error 19— m ean error 19—sett ing 5Ballistic— 557Burst— 6

Com pletely stripped— 284eCorrected— 19 2, 19 4, 56 1 , 566Definition 5Dev iations in— 100Fire at a single— 2 04 , 277Initial— 192 to 1 95 , 285Map— 557Maximum— 13

Modified— 18 8 , 561O bservation of— 100 , 104Verified bra cketing— ^?

1*>

RANGE SCALE. •

Laying by — 19 4, 285

RECIPROCAL LAYING.

— in establishing the base piece on the base line. 146

Para llel fire b y— 162

RBCONNAISSANCE. Part II, App endix 6— b y corps and division comm anders 410— by regim ental and group com m anders. 411 to 415— by battalion comm anders 416 to 425— by battery comm anders 426 to 429— oi ba ttery positions 66— of obse rvation posts 77 to B0— of trench artillery po sitions . 67

D ut ies of—officer 118 , 422Object of— 52Procedure in— 409 to 429Ra pid— 420 to 427Terrestrial— 52

R E FE R THE PIECE 148

REFERRING POINT 148 to 163

RESECTION.

Locating a point by — 47 4, 487

RETICULE 517, 528 , 534

RICOCHET 339

— fire 361 to 364'— graze burts w ith shrapnel 379Conditions for—fire 361Effect of—fire 363

Sheaf in— 361RIGIDITY.

— of the trajectory 38

R O U T E

— of approach 109



25

— 351 —

SAFETY SONE

SALVO.

—with poor visibility 212—in time fire for adjustment 244

Bracketing battery—DefinitionOrder ofTime interval in—

SCALE

Double decimeter—Map—

SECURITY.

Curve ofSlMI-STBEL SHELL

237205firing— 254

207, 243, 245, 254

Range of fragments of—Sheaf of—

SHEAF.Base—Converged—

DefinitionForming parallel—Lateral—Ogive—Open—

SHELL.

—crater—gas

—used in flash ranging—used in sound rangingAdjusting—B— Cast Iron— (See Cast iron shell).D— . . .Gas— (See Gas shell).P—

Percentage of explosive in—Semi-steel—(See Semi-steel shell).Smoke—(See Smoke shell).Star—(See Star shell).Steel—(See Steel shell).Tapered base—Tracer—(See Tracer shell).

SHRAPNEL.

504

504456

. 13

. 3 0 3

349349

346157

112157 to 162. 346

346157

369351 to 354

598578100, 334

305

305

340

305

339

—against machine guns in shell holes. . . . ( . 377—cone 374—for barrage 377Action of— ?26Adjustment with— 239 to 246Adjustment with high—bursts . . . Appendix 16




Base charge— 324Effect of— 374 to 380Effect of burst of— 374 to 380Fuses for— 327Incendiary effects with— 380

Kinds 321 to 326Ricochet graze bu rst with— 379Robin— 325, 326, 376 , 380Sweep of— - 379Zero fuse set ting with— 376

SIGHT ADJUSTMENT 553 to 555

SIGHTING CIRCLE 54$

SITE.—correction in range 35, 193—in high angle fire 36, 180, 192—in mask firing 56, 58—in calculating initial fuse setting 197Burst line of— 6Eurs t plane of— 6Calculation of— 180, 184, 195, 197

Com plementary—correction ' 37Correct—in stripp ing 2846Coirection in— 35 , 37 , 50Definition 3

'Incorrect— in stripping 284c, 285frInitial range with correct— 194Initial range with incorrect— 195, 285Line of— 3Plane of— 3

SlTOGONIOMETER 5 5 0 , 5 5 1

To measure angles with— 551To measure site and find minimum range with— 551

SKETCH.

Panoramic— 107Place— 105, 170 , 182, 183

Visibility— 107, 109SLOPE.

—coefficient 21—table 21Counter— 178Forward— 4, 78Leveling by measuring the— 493Negative— . . 178

Positive— 178Probable error on— 21 , 184Reverse— 4, 178, 267Time fire for effect on— 265, 269To measure a— 515, 516



Paragraphs.

SLOPE CHARTS, AIR BURSTS. . . . Appendix 13. 265

SMOKE SHELLS.

Ammunition consumption with— 280Use of— 280, 335

SOUND RANGING 576 to 593

Objectives in— 577Adjustment by measured deviations in— . . 585Charts for— 584Fire for effect in— 589Fuses used in— 578Methods of fire in— 585Program of adjustments in— 583

Shells used in— 578Telephone communication in— 581Use of the witness point in— 590

SQUARED PAPER 496

STADIA ROD 513a, 530

STANDING ORDERS 109

STAR SHELLS.

Description and use of— 336STATION CORRECTION 183

STEEL SHELL 301

Armor piercing— 301 bBase-fused— 3016Point-fused— 301aRange of fragments of— ^ . . . . 348

Semi-armor piercing— 301 bSheaf of— 348STRAIGHT EDGE 504

STRIPPING 281 to 286

— an adjustm ent 281 to 286, 557 to 566—for deflection 283—for range 284

SWEEP ING F IRE.

—in percussion zone fire for effect . . 258 to 260SYSTEMATIC FIRE 290d

—for effect 261Definition 261

T A N K S .

Fire against— 271TARGET SHOT.

—in percussion bracket adjustment 238—in percussion precision adjustment 214

T E L E P H O N E .

—communication in flash ranging 600—communication in sound ranging 581Duties of—offlcier 423



— 354 —

Paragraphs .

TELESCOPE.

Illumination of a— 532Observation— 531 to 540Site device of a— 534Scissors—. . 541 to 547To measure the angle between two points with— 53?

To measure the site with— 538

Use of—in observation of fire 539, 540

THEODOLITE.

Accuracy of— 126Care of— 552«Definition 117Locating point with— 480 to 490

Use as director 144 to 148, 152THERMOMETER 403

THREE POINT METHOD.

—for locating a point . . . . 132, 472, 473, 486

Unoriented— 473

TIME FIRE.

—adjustment 239 to 252

—effective fire against 358 to 360—for effect behind crest 265 to 269, 567Corrections in— 49 to 51Dispersion in— 23 to 24Radius of effect in— 356 to 357

TOPOGRAPHICAL INSTRUMENTS.

Declination of— 117Definition of— 116

Orientation of— 117

TOPOGRAPHICAL METHODS 464 to 495

TOPOGRAPHICAL OPERATIONS.

—by the battery 134 to 140—by the battalion 122 to 133—in determination of initial firing data . 175 to 183—preliminary to observation 93 to 95

—preliminary to preparation of fire. I l l 118 to 140—without maps 164 to 172Accuracy of— 286

TRACER SHELLS 337

TRAJECTORY. •

—chart 571—in vacuo 8

Definition of elements of— 1 to 7Origin of the— 1Rigidity of the— 38Study of the— 8 to 13Summit of the— 7



— 855 —Par«Jr»ph».

TRAVERSB.Angle— 466Courses in traversing 466, 476Direction and distance 475, 488Fore sight and back sight 479

Locating a point by— 476 to 479, 489Points of a— 476

TRENCH MORTARS.

Concealment of— 67Improvement fire with— 221

TRIAL FIRE 203 , 215 , 389, 390

—in unilateral observation 432 to 438TRIANGULATION SYSTEM 116, 139, 463

TRUNNION.

Correction for the inclination of the—. .Appendix 3

Inclination of the— 40

TW ENTIETH OF A DECREE 14

Vo.

—in initial firing data 188Definition 188Use in shifting fire 287 to 290Use in stripping 284, 565 to 566Variation in—due to powder 46 to 47Variation in—due to wear of gun 48Variation in—due to weight of projectile . . 45

VARIATIONS AND CORRECTIONS DIFFERENTIATED. . 33

VELOCITY. (See V o).Muzzle— 2Variation in— 47

VERIFICATIONS 226

VISIBILITY 212

VOLLEY.

—with poor visibility • . . 212Definition 205WEAR.

—of pieces 22 , 48, 556W ND.

—rose 44Ballistic— 44 , 397 to 401, 405 to 408

W ITN ES S PIECE 297

WITNESS POINT.Definition 95, 293 to 300Determination of— 294Fire with a— 297Qualifications of a— 2-99U s e of_ '293 to 300



— 356 —I'aragrapln.

Use of—in flash ranging 615Use of—in sound ranging -590

WOODS.

Fire against— 246

Y-AZIMUTH.—of line through declinating points 463—of orienting line 426Definition. 116, 462Determ ination of—with aiming circle 527Measuring the— 497To draw a line of given— 498

Y-DECLINATION 4 6 3 , 5 2 5

Y-LINE.—in connection with ballistic wind 408—in plo tting a point 502Definition 116, 459

ZONE.

—of dispersion 20Objective— 181

Safety— 25ZONE FIRE 20 1, 239, 568

—with bilateral observation 447—with gas shell 278—with smoke shell 280Am munition consumption in— 257Command for— 259, 263Laying in— 204

Object 201Percussion— for effect 257, 261Variations of— 270

PAINTED BY BERGKR-LEVRAULT, NANCY ( M . - E T - M . )



47887

COM BI NED^M SBESEA^CHUBRARV

3 1695 00647 4209

AUTHOR A E F , GHQ

Artillery firing

A C C E S S I O NA - '• C '1

artillery firing part 2

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