Du Bois D. Parmelee

In 1850 Du Bois D. Parmelee from New Paltz, state of New York, received the US patent No 7074, for a single column key-driven adding machine. This is the third (known to us) key-driven adding machine in the world, and compared with the previous 2 machines—Luigi Torchi and Jean-Baptiste Schwilgué, it seems rather primitive and nothing more is known about the machine.

The New Yorker Du Bois D. Parmelee is known primarily as an inventor (U.S. Utility Patent Nr. 37637) of a suction socket for artificial limbs, some 90 years before it received general acceptance. Parmelee fastened a body socket to the limb with atmospheric pressure, thus being not the first person to do so, but the first person to do so with satisfactory results.

The adding device of Parmelee (see the lower patent drawing) has 9 keys, which are numbered from 1 to 9 and have increasing heights.

The patent drawing of the machine of Parmelee

The motion from the keys is transferred to the stick (graduated rule) B in the back part. This stick has in his front part teeth, which are engaging with the 2 tongues m and k (figure 2 from the patent drawing). The sidebar of the stick is graduated and numbered in such way, that 1 tooth corresponds to 1 division. On pressing of a key, the lever E will raise the tongue k to so many divisions, according to the digit, written on the key. Then the lever will be returned to the starting position by means of the spring n. When the enetering of the numbers (or the stick will be raised to the uppermost position), the operator can see the number in the sidebar, and then pulls by means of the 2 ropes p the 2 tongues and stick will fall down.

In the patent description Du Bois D. Parmelee also proposed some inprovements, the most important is to improve the visualization, including in the construction gear-wheels and strips.