George Grant

Between 1872 and 1898, George Barnard Grant (1849-1917) of Cambridge, Massachusetts, patented and manufactured in his company Grant Calculating Machine Company of Lexington, Massachusetts, several models calculating machines. He received four patents for calculating machines—in 1872 (US Patent No. 129335), 1873 (138245), 1887 ( 368528) and 1888 (605288).

In 1876 Grant exhibited at the 1876 USA Centennial Exposition in Philadelphia, two calculating machines. First was a magnificent differential machine (see differential machine of Grant). The second exhibited machine was a smaller calculating device, which was described in the first two patents from 1872 and 1873 (see the figure below).

The smaller machine of Grant, exhibited 1876

Grant is reported to have invented this machine while a student at the Lawrence Scientific School at Harvard University (between 1870 and 1872). This machine was reported to be intended for use in counting houses, insurance offices, etc., and was described as a smaller instrument for common operations in multiplication, division, etc. It is a foot in length by half as much in height and width, weighs twenty pounds, and contains less than 400 pieces, less than 75 of which are working parts. It takes numbers up to nine decimal places. According to an exhibition report, this machine, or arithmometer, successfully rivals the well-known one of Colmar.

In 1881, Grant exhibited the calculating machine in his home state at Fourteenth Exhibition of the Massachusetts Charitable Mechanic Association, Boston, 1881, and won a gold medal. The report of the exhibition stated: This calculating machine has now stood the test of practical use, several of the machines having been employed during the past three years. It is admirably adapted for an extensive range of computations in multiplication and division, and surpasses all other instruments now used for such computations in respect to simplicity, strength, compactness, durability, cheapness, rapidity and accuracy of operation.

In 1898, Encyclopaedia Britannica reported that there were numerous crank operated calculating machines for multiplication and division, including machines made by Thomas, Tate, Odhner, Baldwin, and Grant. "Grant's machine consisted of a cylinder bearing a set of rings on which were the numerals. These he terms adding-rings. A similar set of rings is placed on a shaft below, and these he terms registering wheels. In order to multiply, the adding-rings are set to read the multiplicand, and the registering-wheels the multiplier. If the multiplicand were 387432, the crank would be turned three times and a slide shifted, then eight times and a slide shifted, and so on. At the conclusion of the turning the answer could be read on the recording-wheels."

The patent drawing of the machine of Grant, from 1873

The numbers are entered through the openings of the lid (marked with P in the patent drawing), mounted on the sliders g and g'. The results are shown on the digital wheels (which are similar to teeth-strips), placed under the lid. Adding of the number is performed by means of movable carriage C, which can be rotated by means of the handle H. On the lid are cut off slots (or openings in the first patent), in which are are pushed in the pin p. The slots (openings) are graduated with the digits from 1 to 9 and the number is entered by pushing in the pins in the appropriate openings, while the lowest row is for units, upper row is for tens, etc. In this way the entered number can be multiplied by 10 or divided to 10 (by moving upwards or downwards of the lid to one division). Besides the graduated digits are inscribed smaller digits (from 9 to 1), which are complementing to 9 of the bigger digits and are used during the subtraction and division. The digital wheels A, B, C, D and so on, are placed below the slots, and each wheel is divided by two (or three) groups of 10 teeth, each teeth is marked with a digit.

The machine has also a mechanism for zeroing the display of digital wheels.

The pins are acting as a stop for placed below digital wheels, which during the rotation of the handle (carrier) make a motion forward-backward and transfers the numbers from the input to the displaying mechanism.

In his patent form 1873 Grant suggested three variants of the tens carry mechanism, depending of the capacity of the machine.

The arithmetical operations with the machine are performed in the typical for the adding machines way, keeping in mind, that the calculating mechanism can be rotated only in one direction and during the subtraction and division is used complementing to nine.

Later on Grant redesigned the machine, adding a printing device and manufactured his device with success at the end of the XIX century (see the figure below).

The last machine of Grant