On 11 September 1871, Robinson Teasdale, a farmer and miller from Elberton, Georgia (interestingly, in the patent application the town is specified as Alberton, and the inventor’s name in the signature is Teasdell), applied for a patent for Improved Calculator. The US patent Nr. 121687 was granted on 5 December 1871. Besides the patent application, nothing is known about the calculator of Teasdale, so obviously it remained only on paper and had not been implemented in practice.
The improved calculator of Teasdale has formal resemblance with the 20th-century cash registers, with its crank-operated transfer mechanism. In the patent application the inventor stated boldly: With this improved machine examples in addition, subtraction, multiplication, division, square and cube-root, &c., may be worked out with great rapidity. Let’s examine the operation of the calculator of Teasdale, using the patent application (see the patent drawing nearby).
For addition-the stops i being set on the plate g to the figures to be added in as many of the slots as there are columns to be added-one turn of the crank will adjust the faces a of the disks A, so that the sum of the amount represented on plate g at the said stops and the amount seen on said disks before the operation will be seen on said disks after the turning of the crank. The operation is repeated for as many figures as there are in the columns. The operation for subtraction is precisely the same, except that the cover A is shifted so that the faces b of said disks, with their figures arranged reversely to those on the faces a, are seen. For multiplication-the disks A being all adjusted so that the zero or nought of the faces a are seen through the cover-the disks D are adjusted to represent the multiplier on their faces a, and the stops i are adjusted for the multiplicand; then the crank is turned as many times as the denomination of the right-hand figure of the multiplier, then the nought, being at the hole A2 and the notch G coming around to the stop, the frame is ready to shift to the right for the next disk D, to be acted on by the pawl r; but it is restrained by the lever M until all the segments have ceased to work in the last revolution of the crank, which is necessary to prevent the disks and teeth of the segments coming into contact; then said lever being tripped by the cam N, the disks, together with the frame supporting them, will be shifted, and the second disk D brought to the pawl r, to be in like manner turned as many movements as the denomination of its figure of the multiplier; and so on until all the disks making up the multiplier have been acted on, when the product will be seen on the disks A through the holes in the cover above them. Thus the multiplication of any two sums together will be accomplished by as many turns as the sum of the figures in the multiplier added together.
Biography of Robinson Teasdale
Robinson “Robert” Teasdale was born on 11 April 1811, in Darlington St. Cuthbert, Durham, England. He was the sixth child of Michael Teasdale (born 1776) and Elizabeth Robinson (b. 1782), after Ann (1801-1868), Mary (b. 1803), Elizabeth (b. 1805), Hannah (b. 1806), William (1808-1867), and before Thomas (b. 1813).
Robinson emigrated to the United States in the 1830s and married Martha Ann Estill (born 1819) on 14 December 1842, in Franklin, Tennessee. They were the parents of at least three sons and one daughter: James T. (1846-1938), William (b. 1847), Robinson “Robert” Edward (1848-1934), and Mary Emily (b. 1850). Martha Ann died in the early 1850s, and in 1856 in Alabama Robinson married second time Nancy L. Sanders (27 March 1834–14 March 1916) from Habersham, Georgia. The new family had three children: David Allen (1859-1883), Abner Benson (1861-1889), and Annie E. (1869-1952).
Robinson Teasdale lived in Elbert, Georgia, United States in 1860s and 1870s, and in District 267, Franklin, Georgia, in 1880. In US census documents his occupation is specified as keeping gristmill. He died on 6 February 1897, in Toccoa, Franklin, Georgia, at the age of 85, and was buried in Toccoa Cemetery, Toccoa, Georgia.