Home Up | Contact Legal Stuff |
The Bare Bones Hemmi 22 |
When I explain the slide rule to a curious
soul, I say "and then William Oughtred had the idea that by taking
two Gunter rules and sliding them next to each other, he could add
the logarithms directly, without using the dividers". The problem
used to be, when I took a slide rule to demonstrate, my listener
would see in it three, not two, rules -- with as many as 25
scales... hardly a good demo. Actually, I had once seen a two stick
slide rule. It was made in the 18th century, and cost more than my
entire collection... so I was left to do my explanations with a
standard slide rule and hope for the best. Until I got the Sun Hemmi No. 22. Unique among modern slide rules, this one has only two sticks and 4 scales -- truly a bare bones instrument. |
Click photo to enlarge |
The no. 22 was made in Japan in the period 1954-1959, as a basic student rule that was apparently only sold in Asia. Its two main scales enable multiplication and division, with two additional scales for squares and reciprocals. No trig functions, no cubes, no frills. The slide (23 cm long) is held to the single stator by a metal bracket, and a very simple celluloid cursor completes the inexpensive construction, which you can see in the photos below. |
If you lecture about HOC, you're welcome to use this image, in which I photoshopped out the superfluous details to recreate Oughtred's innovative idea at its simplest and clearest. Or you can make your own demo from this raw image. |
Click photo to enlarge |
Exhibit provenance: Paul Ross’s Slide Rule Trading Company. More info: |
||
Home | HOC | Fractals | Miscellany | About | Contact Copyright © 2007 N. Zeldes. All rights reserved. |