Mechanical Accountant model H
This machine is not a proper four-function calculator, but rather a non-writing adding machine. However, I acquired it in a lot together with the Arrow Calculator from the Russo collection, and considered it as a bit of a challenge. I'm sure you'll appreciate why:
The impression that it spent some time at the bottom of a lake didn't improve when opening it up...
Luckily, it had some things going for it as well - all the keycaps were present, and the paper strips wound around the result wheels with their silver-on-black figures were all intact. So while it looks desperate, it should in fact be a rather easy restoration. I decided to attack the rust without doing major disassembly, and that starts by a good spraying with solvent to get all the dirt, grime and dried-up grease out.
... followed by a good scrubbing - this is just the edge cleaned up ...
Halfway there...
and then we start on the keytops - as they were:
Leftmost row cleaned and polished:
...and all rows cleaned and polished
The bottom had been mostly derusted as well.
And these are the felt-covered strips of wood that form the base of the keyboard, prior to washing them.
Since the handle for clearing was broken and lost, a new one was filed from steel strip, and then silver-soldered onto the remaining stub
The paint was taken off with a brass brush:
and the black cover for the result was repainted, with care being taken that the silver dots for decimal positions were kept (by covering them with a bit of grease when painting)
The first attempt at a colour coat ended up being baby-shit brown. Not a good look for a calculator. A darker brown was quickly sourced.
In the mean time the keyboard was reassembled
And after the cover and clearing handle were remounted, the restoration was essentially finished.
Original paint was kept on the bottom shell - s/n 11302
So - how does it work ? Typing in any number on the keyboard, will make it appear both in the control register at the top, and the totalizer at the bottom
Typing a different number will add it to the totalizer, whereas the control register will show the latest entry in any column
For extra security, the bar at the bottom of the keyboard can be hit, which clears the entire control register
And then of course turning the crank on the side resets both totalizer and control register
Not so bad in the end!
The Mechanical Accountant Co. of Rhode Island sold these things. The model H encompasses a most diverse set of machines, with more columns, less columns, extra columns for non-decimal currencies ... but the Museum of American History reiterates that this is the simplex model - if neighbouring columns are operated simultaneously, this results in the loss of the carry, so keys need to be operated from right from left. The machine was invented and patented by Joseph Abraham V. Turck, who later worked for the Comptometer corporation, and wrote the book "Origin of Modern Calculating Machines" in 1921. In it, he does not mention the "Mechanical Accountant", as it must have been crystal clear to him by then that machines had been on the market since the 1880's (Comptometer, Burroughs ...) that worked much better than this contraption.