This relatively late English-built arithmometer represents C. & E. Layton's improvements to the machine originally designed by Samuel Tate. The stepped drum manually operated non-printing calculating machine has a brass and steel mechanism attached in a mahogany case.
The eight setting levers are above a row of windows that show the number set. The zeroing lever for the setup is on the right and an ADD-MULT / SUB DIV lever is on the left. The crank for operating the machine is right of the levers. Below it is zeroing lever for the entry levers. The stepped drums are brass.
The carriage has 9 windows in the revolution counter register and 16 in the result register. On the right of the carriage is a crank that is turned counterclockwise to zero the revolution register and clockwise to zero the result register. When the entry in the result register would become negative (as it might in subtraction or division), a bell rings. It rings again if a number is added to bring the total to zero or more.
Decimal markers slide along rods above the entry windows, revolution register windows, and result register windows.
Handles at both ends aid in lifting the machine. The case lacks a lid. A space for a compartment is on the left side, but it has no cover.
The mark on the front of the machine reads: LAYTONS IMPROVED ARITHMOMETER (/) LONDON 1911 (/) PATENTS Nos 8984 & 12032 - 1909 BÄURLES. PATENTS Nos 1666 & 15261 - 1907. No serial number was found.
The machine is from the collection of Felt & Tarrant Manufacturing Company of Chicago.
Compare 311953, 323657, 323629, and 333922. The approximate date is taken from an existing catalog card and from the machine.
Reference:
Horsburgh, E. M., ed., Handbook of the Napier Tercentenary Celebration of Modern Instruments and Methods of Calculation, Edinburgh: G. Bell & Sons, 1914, pp. 102–104.
