The Fire Alarm Telegraph of New York City. 413

THE FIRE ALARM TELEGRAPH OF NEW YORK CITY, (Concluded from page 352.)

The Repeater

is an instrument of great perfection of workmanship and design. It has a very important and exensive work to perform. When it is necessary to send out alarms it is, of course, of first importance to send to the various engine houses, and next to the street boxes. The last signals would be only for the information of the public. The circuit-wheel, driven by regulated clock-work, is here again employed, but it is constructed far differently from that used in the street-boxes. In this case each revolution of the circuit-wheel is made to throw a single signal. In other words, three revolutions will produce three taps of the bells. The signals are usually sent out with a large battery power. It would be expensive to keep up so large a battery power upon every line as is usually thought best to employ for this tapping, so the circuit-wheel is made very broad on the face, and teeth faced with thick platina are placed spirally upon it, and double springs, also heavily armed with platina, are placed so that the teeth come successively up to the springs and throw the battery power into them. Practically, the division is into eight sets of springs and eight sets of teeth on each wheel or roller. As the circuit-wheel or roller revolves it communicates successively the battery power into springs 1 2 3 4 5 6 7 8, and as these springs unite with the lines the power is successively thrown into the eight successive lines. The full power of one large bat- tery is thus brought to bear successively on the different lines in order, and a sufficient number of these circuit wheels, with their springs, are coupled together by gearing, so that all the lines through the city may be charged every revolution. How many of these lines shall be charged is entirely under control. The switch-board allows the operator to throw any number on or off of the repeater. The circuit-wheels are driven by clock-work and weight, and as long as the machine is made to run the wheels would go on to tap regular successive strokes on the bells through the city. But the requirements of the fire service are such that numerical signals from 1 to 998 may be sent out. Any such signal may be sent by the machine--provided that a plan for cutting off the currents from the rollers or circuit-wheels, at regular intervals, be provided. Thus if we wish to send the signal 2 8 we allow the circuit-wheels, in full battery connection, to revolve twice, all the bells on all the lines will tap twice, but as they revolve the third time the battery connection is severed from them, and they revolve inoperative. As they make their fourth revolution the battery power is again turned on and three revolutions are made, giving three more taps. At

414 Mechanics, Physics, and Chemistry.

the conclusion of the third tap the battery is again cut off and re: mains cut off until it is time to commence a second "round," then the same process is repeated. The cutting off and throwing on of the battery is accomplished by the use of regulating wheels--each one cut to make the different desired signals. These wheels have teeth on them. They can be attached to or detached from the re- peater with ease and rapidity. Each tooth passes a certain point in the same space of time occupied by one revolution of the circuit- wheels. The agency of the teeth is to press certain springs together firmly. The springs being fixed, and the wheels revolving, if the first and second tooth of the wheel touch the springs and press them together, the battery power flies to the circuit-wheel. If, however, the next tooth is missing, the springs do not come in contact and the battery is cut off, what signal shall be sent is, therefore, simply a question of how many teeth are left upon the regulating wheels, and in what order they occur. While regulating wheel 3 2 7 is attached to the repeater the instrument cannot send any other sig- n a l - i t is impossible to make any mistake.

But a difficulty presents itself in carrying out this system of auto- matic telegraphy. The relation of revolution of the two wheels, that is the regulating and circuit-wheel, must be fixed ; in order to send 998 the revolutions must be as 1 to 30, as 30 teeth would be required to send all those 26 taps and the pauses between. It is quite evident, then, that the pause between the completed signal 23 and its repetition is much greater than between 998 and its repetition. It is desirable to have the pauses between rounds equal, and to be able to adjust it to a certain number of seconds. This is accom- plished thus :--Instantly after the laststroke of every signal a p.in on the regulating wheel actuates a lever which immediately m- creases the speed of the train, which speed is kept up until the ma- chine stops itself precisely at the point on the regulating whee l where it commenced its action. At the same instant that the speed is increased, another train of wheels is started in action which runs for a certain regulated interval of time and then stops itself, but before stopping itself it restores the parts of the other train to the condition they were before the speed was increased, so that when again it starts it is upon the normal slow speed. The further office of this second train is just, as it is about to complete its action, to start again the first train, so that the complete signal is repeated. Now, as the second train is not tripped until the last working tooth of the regulating wheel acts, the regulating or second train goes into action much sooner on a short signal than on a long one ; so that the first train cannot go into action again till the second train stops; so that the effect is after a short signal the first train is tripped and started again almost immediately after it comes to rest ; but after a long signal it has to wait until nearly the whole time occupied by the movement of the second train, and thus the pause is completely equalized. These actions of the two trains upon each other continues, and the signals are repeated with great accuracy

The Fire Alarm Telegraph of New York, City. -t15

and uniformity, as long as the trains continue running; but it is arranged that after a certain interval the movement shall lock itself into rest again, so that nothing can again call it into action except the will of the attendant who must make two movements analogous to the setting of a hair trigger and then pulling it. The locking arrangement is contrived so that it can be set to any number of rounds or repetitions of signals required by the department. I f set to three, it will complete three rounds and then lo¢~k itself, or if set to one, but one alone will be sent.

The object then of the repeater machinery is to send to any num- ber of stations a mechanically correct numerical signal, to repeat it, whether short or long, at regularly timed and equal intervals, and to repeat it as many times as required. This machine does this, requiring that the attendant should perform only two simple ope- rations. First, the attachment of the proper signal wheel. Sec- ondly, the starting of the instrument.

No further attention is required; the operator has his mind re- lieved at once from responsibility; he may receive a second alarm or attend to other instruments.

Before giving up this instrument to the charge of the Fire De- partment, it was tested with as much work as would ordinarily be given to it during eighteen months' service. Supplementary to this elaborate instrument is a smaller one for sending any other signals outside of the numerical alarms, such as time signals, or any general orders that are to be sent to engine houses, which can

b e expressed numerically. It is also ready for use in any emer- gency which might prevent the use of the larger instrument. All such instruments depend for elosing of circuits upon springs which press upon toothed rollers. In these machines these rubbing con- nections are armed with thick pieces of platina very accurately fitted. The springs are double, either one of the two being com- petent for the work. The apparatus is closely boxed up in plate glass cases, yet as particles of dust will sometimes get into even such eases, and a chance exists of lessening the perfection of this circuit closing, a test machine is added whereby the exact condition of any spring throughout the apparatus can be ascertained at any time in less than a minute. When not in use each one of the cir- cuit-wheel rollers, with its springs, is switched off from the lines. Attached to the machine, and behind the other works, is a long roller; its office is to press combinations of springs together; if moved twenty degrees the entire eight sets of springs of the first roller are thrown into connection with a battery and a series of eight magnets; if moved forty degrees the second roller is in like manner connected with the battery and the ~ight magnets and so on through the series.

The effect of this will be when the machine goes through its performance, that these eight magnets will be charged successively instead of eight lines of wires. :Now, these eight magnets play the

416 Mechanics, Physics, and 57;emistry.

role of ringing eight bells, whose tones correspond with the natural scale so familiar to almost every ear. A break in this scale is very quickly detected. If one note is missing, or is struck unevenly, the spring connected with that note is not perfectly effective. De- tection of the slightest imperfection is thus made quick and sure. The entire number of 108 springs could thus, if desired, be tested within ten seconds. To receive the alarms thus sent out by the repeaters, machines are set up in the engine houses and other sta- tions called--

~Tecl~anical Gong Stri]cers.

These are large gongs struck with a hammer, moved with an apparatus which is driven by a weight, and wound up like a clock. 2x very delicate trigger is combined with this mechanism, which is capable of very fine adjustment. This trigger is pulled by the mag- net and the machine released, and one blow struck. The object of the machine is to give a more or less powerful blow proportioned to the size of the bell, which may weigh from five pounds to ten thousand. The trigger which starts the action is very easily moved.

Such are the principal machines used in the Fire Telegraph, but it is proposed to supplement them with a few circuits independent of the fire lines which may connect all alarm stations, or officers' quarters, with the Central Office, so that special orders, directions for repairs, investigation of difficulties and general discipline, may be easily managed without breaking into the Fire Telegraph lines, which are thus left exclusively for alarms, for although each sta- tion may be made a complete telegraph office in emergencies with the facilities provided, it should be used only by the electric corps of management and not by the department generally.

In the very thorough tests made of these lines in order to bring them to perfection, two principals and four subordinate corps of electricians have, with the aid of the most complete apparatus pro- bably ever used for such purposes, reduced the working condition and efficiency of the whole number of lines, from an aggregate im- perfection of over 900 degrees to absolute freedom. With this apparently large aggregate escape, or imperfection distributed over all the line, it is quite possible to have all the functions of the lines and apparatus performed ; but step by. step every cause of disturb- ance has been so thoroughly removed, that the very last deflection at 3½ degrees is announced by the Electrician-in-Chief to be removed, and not the slightest imperfection exists at the moment of writing these lines.

The system of telegraphy, which is the foundation for this Fire Telegraph, is called the Central Office System of the American Fire Alarm Telegraph, but the special adaption to the requirements of this metropolis, the machines to carry'out the modified system, the batteries and the automatic street boxes are the inventions and patents of Charles T. Chester, of the firm of Charles T. & J..N.

The Anvil ProtuSerance. 417

Chester, contractors for the construction, under whom the electri- cal corps have erected and constructed the apparatus. The survey and construction of lines, involving immense labor, has been super- intended by Colonel Stephen Chester, of the Engineer Corps, who served, during the war, in the Army of the Potomac.

THE "ANVIL" PROTUBERANCE

Of the Total Eclipse of August 7, 1869, as observed near Sioux City, Iowa, with a flint-inch telescope.

BY WINTtlROP S. GII.MAN~ JR.

T~E large protuberance visible between angles 230 ° and 245 ° in the late Solar Eclipse, and which was so readily seen by the unassisted eye, was, in the telescope, an object of surprising beauty and grandeur. I propose in this paper to notice briefly some of its striking fcatures. The atmosphere of St. Paul Junction, where I observed, was more than usually favorable to good definition, and the performance of my instrument I have never seen sur- passed.

The " A n v i l " protuberance was first seen by an assistant with a small glass, several seconds previous to totality, and I could still see it in my instrument when a considerable crescent of the re- appearing sun had rendered the corona invisible. Several months study of the sun's surface had prepared me to expect the more re- markable protuberances in the southern hemisphere, and having selected the south-western quadrant as an especially favorable locality, from the presence of faculous ridges near the limb two days prior to the eclipse, the bright, "anvil "-shaped mass instantly attracted my attention. 2,_ hasty glance at other portions of the moon's limb satisfied me that the "anvi l" protuberance possessed greater interest than any other, and I, therefore i devoted my whole time to its consideration, except so much as was employed in ob- taining several outline sketches of the corona.

The limits of the corona were brought into view by a slight movement of the instrument, and its extent was quickly indicated on diagrams previously prepared for the purpose. At the same

VOL. LIX.--THII~D S~I~IES.--~o. 6,--Ju~E~ 1870. 53