The Adding Machine of Andrew Stark

The American Andrew Stark (19 Mar. 1852-16 Feb. 1920) from Chicago was a prolific inventor from late 1800s and early 1900s. He is a holder of quite a few patents for grain-binders, harvesters, railway facilities, furniture, a fiber vessel, etc., but also of a rather interesting adding machine, which deserves our attention.

The adding machine of Stark (US patent №308528 of 1884) has a series of numeral wheels (see the lower patent drawings), each provided with 3 sets of figures running from 1 to 9 and 0.

Pivotally mounted upon the axis of the numeral wheels at each end are sector gears E1 and E4, in which are pivoted a square shaft E, extended from one arm to the other across the face of the numeral wheels. The shaft E, is claimed to be held in its normal position by a spring so that a pawl, E2, shiftable mounted on the shaft, designed to ratchet or actuate the numeral wheels forward, may engage with anyone of the numeral wheels ratchets.

Leupold's Napier's rods device

Andrew Stark's machine patent drawings

Leupold's Napier's rods device

A bail (marked D), is pivoted to standards A1, of the frame of the device, and is provided with 2 radial racks D3, which mesh with the sector gears E1. It may be conceived that the act of depressing the bail D, will cause the actuating pawl E2, to operate whichever numeral wheels it engages the ratchet of.

The bail D, is held in its normal position by a spring D2, and is provided with nine keys or finger pieces d, eight of which co-act with the stepped plate G, to regulate the additive degree of rotation given to the numeral wheels, while the ninth has a fixed relation with the bail and the bail itself is stopped.

The keys d, marked from 1 to 8, are pivoted to the bail in such a manner that their normal relation to the bail will allow them to pass by the steps on the stepped plate G, when the bail is depressed by the fixed No. 9 key. When, however, anyone of the keys numbered from 1 to 8 is depressed, the lower end of the shank of the key will tilt rearward, and, as the bail is depressed, offers a stop against the respective step of the plate G, arranged in its path, thus stopping further action of the actuating pawl E2, but offering nothing to prevent the continuation of the force of momentum set up in the numeral wheels by the key action.

There was small use in stopping the action of the pawl E2, of the ratchet and numeral wheels, impelled by the pawl, could continue onward under its momentum.

The carry of the tens transfer device is of the same order as that described in the machines of Pascal and Hill; that is, a one-step ratchet-motion actuated by a cam lug or pin from lower wheel. The carry transfer device consists of the lever F, and pawl f4, acting on the ratchet of the upper wheel which is operated by the cam lugs b5, of the lower wheel acting on the arms f1 and f2 of the lever F.

The machine of Stark was provided with but one set of keys, but the arrangement for shifting the driving ratchet pawl E2, from one order to another, so that the action of the keys may rotate anyone of the numeral wheels, gave the machine greater capacity than the single digit adders. Obviously, there was no means provided by which the rotation of numeral wheels could be controlled, it was merely a device for rotating numeral wheels and was therefore lacking in the features that would give it a right to the title of an adding machine.