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Automatic Adding Machine Co. Golden Gem

• Type: Adding Machine
• Size: 4.75.5 x 3 in / 12 x 8 cm
• Material: Steel

The latest patent date on the unit is from 1907, but the serial number, 68848, suggests a later manufacturing date, perhaps 1910 or 1911 (based on reports of advertising stating that 80,000 units were in service by 1912). Original price for this model was $15.00.

I got the unit bare. Some units were boxed, some apparently came in a leather case. Advertising suggested that this could be carried in the pocket. Possible, it's only 3/4 in (2 cm) thick. But the thing is heavy. Over a pound and a half (750 g). Perhaps our forebears in the early twentieth century had large, specially reinforced pockets.

The unit is chain driven. The user inserts a stylus between chain links and pulls downward. Unlike the Addiator and its ilk, ten's carry happened automatically (but gods help you if you add one to 9,999,999...). The stylus was (from photos) a woodclenched wire about 2 mm thick. The wire was cut off square (that is, not rounded). Stylus scratches are visible on the backplane behind the chains.

Subtraction was not immediately available, but could be performed via 9's-complement addition following complicated directions in the manual.