Original manufacturer's fitted boxes.
ca1920 / ca1905
by INSTRUMENTS - PLANIMETERS
ca1920 / ca1905. Original manufacturer's fitted boxes.. Near Fine.. Two Planimeters in their original velvet and satin lined boxes. The Willis instrument retains its original 8 pp. instructional pamphlet.
Planimeters are designed to find the area of a figure (profiles, plans, sections, indicator diagrams) drawn to any scale on a plane surface by simple mechanical operation. The area is computed by tracing the outline of figure (the maximum was a figure of 22 inches in diameter for this size instrument) with the tracing point and reading out the result on a graduated measuring wheel; the scale on this device will read out to hundredths of a square inch. It is based on a design by the Swiss mathematician Jacob Amsler in 1856 who licensed it to Keuffel & Esser. The K & E instrument offered here has their catalog identification number 4211. The Willis design uses somewhat different construction and a novel readout design that purports to enhance accuracy because its tracing arm is able to move in a uniform ("frictionless") precise manner without regard to the paper or surface quality. The readout can be changed to any of six scales provided with the mechanism. The last patent date cited is 1901 with an instrument serial number 5592. See Zoller, Instruments and Methods ...., SIS Bulletin, v. 75, 2002, pp. 11-17. (Inventory #: 21058)
Planimeters are designed to find the area of a figure (profiles, plans, sections, indicator diagrams) drawn to any scale on a plane surface by simple mechanical operation. The area is computed by tracing the outline of figure (the maximum was a figure of 22 inches in diameter for this size instrument) with the tracing point and reading out the result on a graduated measuring wheel; the scale on this device will read out to hundredths of a square inch. It is based on a design by the Swiss mathematician Jacob Amsler in 1856 who licensed it to Keuffel & Esser. The K & E instrument offered here has their catalog identification number 4211. The Willis design uses somewhat different construction and a novel readout design that purports to enhance accuracy because its tracing arm is able to move in a uniform ("frictionless") precise manner without regard to the paper or surface quality. The readout can be changed to any of six scales provided with the mechanism. The last patent date cited is 1901 with an instrument serial number 5592. See Zoller, Instruments and Methods ...., SIS Bulletin, v. 75, 2002, pp. 11-17. (Inventory #: 21058)