Non-electric Calculating Devices

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Surveyor's have always needed the ability to perform mathematical computations.  Prior to the introduction of electric calculating machines, there were many devices used by surveyors to speed their work with various efforts to increase accuracy.  The following display shows several examples of these calculating devices used during the late 1800's thru 1960's prior to the advent of modern digital devices.


brunsviga.jpg (62439 bytes)Brunsviga "Midget" Calculator


Add, subtract, multiply, divide and square root.  Allows 9 digit by 10 digit calculations.  Patented in 1906.

thacher.jpg (61860 bytes)Thacher's Calculating Instrument


Equivalent of a 360" long slide rule, allows calculations to a precision of 1:10,000.  Patented in 1881.

fowler.jpg (63284 bytes)

Fowler's "Magnum" Calculator 


A multi-scale circular slide rule.  Early to mid 1900's.

fullercalc.jpg (59171 bytes)The Fuller Calculator


Equivalent of a 500" long slide rule.  Allows calculations to a precision of 1:10,000.   Early to mid 1900's. 

otisking.jpg (63554 bytes)Otis King's Patent Calculator


Equivalent of a 60" long slide rule


curta.jpg (57431 bytes)Curta Calculator


Add, subtract, multiply, divide and square root.  Allows 6 digit by 8 digit calculations.  The "field crew" calculator of the 1950's and 60's.


sliderule1.jpg (63136 bytes)


Traditional 6" and 12" Slide Rules




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