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U.S. Patent number: 487,824
Filed: Feb. 15, 1892
Issued: Dec. 13, 1892
Inventor: J. W. Culmer
Assignee: The Computing Scale Company
In the patent, Culmer described how someone would use the device:
"In using the computing-poise with the weighing-scale the operator sets the poise at zero on the beam and the decimal-disks each show "0" at the face-opening. The pointer, if then set at 10 on the price-arc, will thereby move the cam 18, and thereby carry down the disk 8,theyoke-frame, and its connected roll 12 nearer to the center of the disk 7, and assuming the pound-divisions to be two inches apart, or any other fixed distance, the disk 7 and the decimal-disks 4, 5, and 6 will be moved ten times the distance upon their axis as they would if the pointer were placed at "1" on the price-arc and the roll 12 at the periphery of the disk 7."
Image taken from U.S. Patent 487,824 - Digitized by Google
U.S. Patent Number: 580,862
Filed: Jan 26, 1897
Inventor: Otto Heckel
In 1897, Otto Heckel was issued a patent for a machine in which a "roll of wire-cloth or screening or other material may be placed, and by unwinding the same from this device it measures the length desired and calculates the number of square feet and gives the amount it will cost."
Image taken from U.S. Patent 580,862 - Digitized by Google
U.S. Patent Number: 641,517
Filed: Sep. 23, 1899
Issued: Jan. 16, 1900
Inventor: Charles E. Keel
Looking for a ways to quickly and accurately calculate taxes, Charles Keel described his invention as follows:
"The invention consists in a manually-operated machine consisting of a pair of main rotating disks, one of which contains numbers representing valuations or base-figures and the other of which contains numbers representing results or amounts of taxes or percentage, a pair of rotating numbered disks to show the higher denominations or order of figures in connection with those on the main disks, intermediate gearing whereby the disks are caused to rotate in the proper ratios of speed to effect the desired results, and a frame whereby the several parts are supported."
Image taken from U.S. Patent 641,517 - Digitized by Google