Antique Pocket Watch Type Slide Rule/calculator, C1890

Antique pocket watch type slide rule/calculator, c1890

The Calculigraphe chronograph was made in Paris at the end of the 19th Century by Henri Chatelain.

It solves multiplication, divisions, fractions, squares and square roots, cube and cube roots, miscellaneous roots and power, logarithms, areas of circles, sines, cosines, and tangent of angles.

The circular slide rule closely follows the design of the Boucher Calculator, which was introduced in 1876 and is thought to have been the first commercialized circular slide rule.

One dial is fixed and has four circles represent two scales, the outermost circle is a scale of equal parts, and the inner three circles are separate sections of cubic root of a number specified by the pointer on the opposite side.

The dial on the other side of the calculator can be rotated by turning the crown, on which there are three different scales on four circles, the outmost circle is a scale of logarithms of sines of angles, the second one is the ordinary logarithmic scale, and the inner two circles are the square roots of the number on the logarithmic scale. There is a fixed pointer engraved on the glass cover, and the movable pointer can be rotated by pressing down the small side button while turning the crown.

The calculator is in good condition and working well. A little brown marking around some of the screws but not too noticeable to the naked eye. Original blued steel hands.

The case is nickel plated, there is some wear to the sides.

The calculator has a glass lens on each side, both in good condition, one has a 5mm mark but not very noticeable at all.

52mm diameter excluding the crown and the button.

The watch comes in a new presentation box.

ALL PRICES INCLUDE UK POSTAGE (because of GPSR legislation, we no longer post items less than 100 years old to Europe, including Northern Ireland).

Please contact us regarding international shipping.

All of our watches are checked over before listing, and are also checked for accuracy which is usually within around +/- two to three minutes over 24 hours (unless otherwise stated), which is considered respectable for a vintage watch.

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With regards to appraisals / valuations, we receive a huge number of information requests each day and unfortunately do not have the manpower to deal with them all individually. Our advice would be to contact a local auctioneer for a full appraisal.