The Museum of HP Calculators Slide Rules In 1614, John Napier discovered the logarithm which made it possible to perform multiplications and divisions by addition and subtraction. (ie: a*b = 10^(log(a)+log(b)) and a/b = 10^(log(a)-log(b)).) This was a great time saver but there was still quite a lot of work required. The mathematician had to look up two logs, add them together and then look for ...
www.hpmuseum.org/sliderul.htm
Table of Contents Subscription info UNITED STATES PATENT OFFICE EDWIN THACHER, OF PITTSBURG, PENNSYLVANIA SLIDE-RULE SPECIFICATION forming part of Letters Patent No. 249117, dated November 1, 1881 To whom it may concern: Be it known that I, EDWIN THACHER of Pittsburg county of Allegheny State of Penn sylvania, have invented or discovered a new and useful Improvement in Slide-Rules; and 1 do ...
www.americanartifacts.com/smma/thachpat.htm
Sphere's Slide Rule Universe is a repository for slide rule information, pictures, history and links to sellers, other slide rule sites and experts, and an on-line slide rule store. Located in Kelowna, BC, CANADA.
www.sphere.bc.ca/test/scales.html
Napier's Bones This is a 6-inch Pickett all-metal slide rule (Model N 200-ES), with case. Let me explain: I was playing with Apple's Make QTVR beta yesterday and suddenly had the urge to rotate a very wide image just a skosh to make its ends match exactly. (Fancy that.) But how much to rotate Hmmm. Looks like a job for Trig. So I asked my wife if we have a scientific calculator that works. No, ...
www.mwbrooks.com/bones.html