The Adder Calculator by CH Webb NY

This is the earlier version of the Webb adder. It was patented on 10 March 1868. The device consists of two interconnected metal dials, one small and one large, mounted on a wood figure eight. The larger numerator wheel has numbers from 0 to 99 and the smaller wheel has numbers 0 to 49 representing the hundreds. The apparatus has automatic tens-carry. Calculations are done by rotating the dials using a stylus (included) inserted into the holes in the surface of each dial. Engraved in to the larger wheel is the inventor’s name: “CH Webb NY. The Adder Patd March 10th 1868”, a small pointing hand in also engraved pointing to zero location, and an arrow to show the direction to dial. The Adder is in good working condition. In 1889 Webb released a newer version of this adder. This newer version has been duplicated many times over, making this, 1868, device very collectible. Overall length is 17 cm (6.7 inches)