RARE Thacher's Calculating Instrument/Slide Rule by Keuffel & Esser CO NY 1917

RARE, antique 1917 Thacher's Calculating Instrument by Keuffel & Esser CO, of New York, Model No. 4012, patented by Edwin Thacher in 1881, in its own mahogany case, including original manual! This is considered the King Of Calculators!

The Thacher calculator has a unique sliding drum design whose scales total over 30' long if laid out in a line. Edwin Thacher first patented the idea for this slide rule/calculator in 1881 in England. The idea was an immediate success with the scientific and engineering communities.

Keuffel & Esser bought the rights to sell and manufacture the popular slide rule. Stanley initially produced them in England for Keuffel & Esser and production was moved to the United States near the turn of the century.

The Thacher calculator was first offered by K & E in their 1887 catalog. This calculating instrument has been well cared for, as evidenced by the condition of its 107 years! The scales are in AMAZING shape for being over 100 years old.

This piece is 99% intact! The scales have a nice, even patina. There is one small spot where a piece has come off (see photos #16,17) and one small spot where a piece is slightly detached. Some very slight spotting on the brass, consistent with the antique age of the piece.

The scales are on revolving brass rings, and there is a 19 sliding inner cylinder. The instructions on the mahogany base are in pristine condition. The mahogany base measures 21 1/2" in length, 5 1/2" in width, and 3/4 in height.

The entire calculator is 22 in length including the knobs used for turning. The outer mahogany case measures 24" in length, 6 1/2" in width and 6 1/2 in height and has two hook closures. Some scratches/stains are present on the case. The original label is on the inner lid.

The original manual, measuring approximately 6" x 9" - says, Directions for Using Thacher's Calculating Instrument, Keuffel & Esser CO, New York, 1917, Price One Dollar. Note: There is a tear in the front cover.

The National Bureau of Standards (now the National Institute of Standards & Technology) declared this object excess property and transferred it to the Smithsonian in 1965. This exact model, the 4012, now resides in the Smithsonian, in the National Museum of American History!