Monroe model K - for english currency
A very, very odd machine. I've never seen one before, if anyone has one of these lurking around, or literature (sales brochure ...) pertaining to it, I'd be happy to hear about it. The Science Museum in London has one in the Mathematics collection (object number 1925-202), but unfortunately they have no picture of it (yet ...)
This was a surprise find in a local (!) second hand shop. It is a Monroe model K, but a special version suited for English currency - and very well suited at that! The main competitor of this machine was the Odhner Lusid, which was difficult and counterintuitive to use - this machine, however, is simplicity itself. There are two settings to the carriage. If it is to be used as a regular four-function machine, the carriage is put towards the left stop, and the dimes column on the keyboard is blocked so it cannot be used - hence the red "1" key. All the other keys work as usual.
The red button on the carriage shift allows to lift the carriage over an additional stop 2 decimal places wide, so it is in its very leftmost position. Now calculations are done in pre-decimal £,s,d, i.e. 20 shillings to the pound, and 12 dimes to the shilling. The numbers 2-9 in the leftmost shilling column are now blocked - it is only possible to enter the numbers 01-19. All the carries are correct - in the section for fracions of dimes it carries from 3/4 to 1 penny, when the pennies reach 12, they carry to 1 shilling, and as soon as the shillings column reaches 20, it carries to a pound. The following pictures, of twice adding £111111, 13s, 6 3/4d illustrate this - the result, £2222223 (0)7s 1 1/2d is completely correct.
