Miscellaneous Calculating & Measuring Devices
The
slide rule was the basic personal calculating tool engineers used
before the advent of electronic calculators and personal digital
computers.
Elegantly simple, this mechanical analog computer uses the concept of
adding and subtracting the logarithms of numbers, which results in the
same solutions as
multiplying and dividing the numbers themselves. Its precision to three
significant figures was adequate enough to help build bridges,
dams, jet fighters,
and send astronauts to the moon. It is estimated that 40 million slide
rules were manufactured between 1900 and the late 1970s.
As
digital computers allowed the exploration of increasingly
dynamic computational models of real life systems, engineers abandoned
the precision limitations of slide rules for electronic
calculators.However, early calculators had their drawbacks. A major advantage of slide rules is that they require no batteries to operate, as the author found out during a second year calculus exam when his then state-of-the-art electronic calculator's battery died. Original batteries replaced with more modern (and reliable) technology, this 1974 calculator is still in working order.
Front
BackThe Moorlane Company "Pipe Pit Gage" is a mechanical gage designed to help the operator standardize the measurement of pits in steel and cast iron pipe. The stainless steel device is positioned long edge on the pipe so that the stylus on the indicator arm fitted into the pit being measured. The indicator arm is rotated around a pivot point until the end of the stylus bottomed out in the pit. The depth of the pit is read on the scale in either 1/16" or mil (thousands of an inch) intervals.
Price, complete with leather case, was $7.50 in 1958. A similar device from another manufacturer is currently available for about $65.