Marchant Calculating Machine Company

The first Marchant calculators differed greatly from their later Silent Speed Proportional Gears machines, which were by far the fastest of their type, running at 1,300 cycles per minute.

Their mechanical design was very unusual in that their result dials (sums, differences, and products) moved at speeds proportional to the digit in the corresponding column of the keyboard.

If one held down the + bar, in neighboring columns to the left (with zeros for them in the keyboard), one could see two or maybe three higher-order dials moving at the speeds one would expect.

Omitting important details, this cam determined the amount of movement needed to realign the result dials.

Some calculators that had been serviced had dials that were mispositioned by (probably) 3.6 degrees; the gears weren't quite meshed correctly when reassembled.

The calculator was very complicated compared to, for example the Friden STW, a machine notable for its relative internal simplicity.

The Marchant mechanism, internally, differed profoundly in many respects from other makes of calculators of the same general variety.