slide rule wrist watches 3

Slide Rule Wrist Watches

ByBob Adams

IM 2010, Leiden The Netherlands

A simple concept

First Slide Rule Watch

Meyrat & Perdrizet Circa beginning

19th Century

First Slide Rule Wristwatch

Mimo-Loga, Juvenia and the Breitling1940’s patent

Types of Slide Rule Wrist Watch 1

Calculating Watches

Ventura

Types of Slide Rule Wrist Watch 2

Aviator Watches

To replicate the E6-B functions

Time Speed Scale and Conversion marks

Types of Slide Rule Wrist Watch 2 cont…

Examples

Breitling Navitimer with 9-hour speed scale.

(Note: not all Navitimers have this scale)

Time Speed Scales 1

• Align 16 on the outer scale with the speed index

• 24 on the outer scale corresponds to "1:30" on the inner scale• Thus the answer is 1 hour and 30 minutes

Obtain the time required for the flight of an aircraft at 160 knots for 240 nautical miles.

Time Speed Scales 2

• Align 25 on the outer scale with “1.40” on the inner scale

• The speed index corresponds to 15 on the outer scale• Thus, the air speed for the flight is 150 knots

Obtain the knots speed for 250 nautical miles with a flight time of 1 hour and 40 minutes

Scales 1

C and D scales

CI scale

Time Speed Scale

Scales 2

Trigonometric Scale

Gauge Marks

Category Gauge Mark Value

Distance Nautical Mile 660 or 327

Statute Mile 760 or 380

Kilometre 1222 or 611

Fuel Litres 485

Fuel Lbs 766

Oil Lbs 960

Imperial Gallon 1065

US Gallon 1280

Mathematical Pi 3.14

Seconds 360

Lbs 3630

Kgm 1623

Feet 1430

Metres 4360

Cursors

Seiko 6138-7000

Rare

Index Mark

Calculating Watches

Index Mark is 1 positioned at the 12 o’clock position

Index Mark

Aviator Watches

Index Mark is 6 positioned at the 12 o’clock position

AccuracyVariable

Some good

Some not so good

Evolution

Thank You