When it first came out in 1887, this baby went for a whopping $30 - equivalent to $550 in Y2K money. The inner cylinder can be slid back and forth, and rotated, to align the inner scale with the outer scale.
The scales - the longest ever made at the time - are broken into a fourty small sections, which are arranged in parallel and cylindrically. Or at least they would be if I had any clue how to use it.ĭesigned by Edwin Thacher in the late 1870's, and marketed by K&E as the model 40, the Thacher had a scale length of sixty feet and could be read to as many as five significant figures. In the case of the Otis, the scale was almost sixty-six inches long! This let the scales be read to more significant figures than usual. The advantage of a cylindrical (actually helical) rule is the great scale length, and the precision that goes with it, in a small package. The Curta is a very cool machine, designed by Curt Herzstark while incarcerated in a Nazi concentration camp! This amazing little machine can add, subtract, divide, multiply, fit in your pocket, grind pepper, predict the weather, and unlike those boring electronic calculators, the Curta has ten billion moving parts! If they're yours and you want me to remove them, contact me and I will be happy to accomodate you.
These images were stolen without remorse from eBay. Y'know, just in case Santa Claus stumbles across this site. These are slide rules or adding machines I don't have, but wish I did. This book includes a Lawrence model 10-B with a magnifying cursor. The Slide Rule and How To Use It by Hobart H.Speed and Fun with Figures: Three Books in One, D.How to Use Log Log Slide Rules by Maurice L.Slide Rule: How To Use It by Calvin C.Quick and Easy Lawrence Slide Rule Instruction Book, Lawrence Engineering Service, Peru, Indiana, ©1939, 1940.This book came with a Keuffel & Esser N4053-2 (labeled "R. The Polyphase Slide Rule by William E.Something like "?evett" written on the cover, but I can't quite make it out. The Log Log Duplex Decitrig by Lyman M.It works just like the original does, only it fits in my pocket. I gave the original back to my wife - this is a 1/2 scale version I made by reducing the original on a photocopier. I've posted this on the Maille Artisan International League website here, where it can be downloaded, printed, and made. This slide rule is for calculating the aspect ratio (ratio of wire diameter to ring diameter) of the links used in making chain maille - another of my many, many hobbies. This was an experiment I've never really used it for anything.Ĭhain Maille Link Aspect Ratio Calculator The scales, from top to bottom, are: Log10, r(1-x^2), x^2x, exp. I hope none of them were carrying slide rules. I made this for playing Silent Hunter, and sank a LOT of Japanese merchantmen with it. On the back, it has linear scales, 0-360|0-360|0-180-0 (Double Naysmith Director). On the front this slide rule has A|B|Sin scales on two wheels. Navigation Calculator, 3" Circular Duplex I'd make a circular slide rule out of AOL CDs. Just think of the fun I could have if I had a CNC engraving machine. Very much like the way celluloid scales are glued to mahogany or bamboo to form a "real" slide rule. The bodies were formed with layers of cardboard glued together, and the prints were then glued to the top. The scales for these were usually designed on a computer and printed out with a laser printer. There have been others, but I don't know where they went. Here are some of the slide rules I've made for my own use. Not sure what an aspect ratio is, exactly? Here's a handy explanation:Įverything You Ever Wanted To Know About Aspect Ratios.Ĭan't find the weave that you're looking for? Try Slide Rule Collection My Own Concoctions (NOTE: Calculated is not a person it indicates the "AR Works" and "AR No Work" values have been obtained by either trigonometry or computer modeling.) All aspect ratios are true aspect ratios, obtained by measuring the rings with calipers, so springback is included here. If an outside source was used, he/she/it is listed in the "Info From" column. This table is compiled mostly by my trial and error, but a few "Preferred" numbers have come from outside sources.
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