Sixty years ago this month, the table of contents of the September 1966 issue of the British Magazine Radio Constructor teased that there was an article entitled “Adding Machine for 12-Volt Operation.”  I wonder if readers were slightly disappointed when they got to that page.  It probably wasn’t quite what they expected, but it literally met the definition.

It was constructed from a telephone dial and an electro-mechanical counter. The author was tasked with creating a device “to be used for motor car rallies, so that the number of miles to be covered could be totalised.” You dialed in the miles, and the device continued adding them until the mechanical reset button was pressed. It would still work for numbers greater than 10, thanks to the zero on the dial. If one had to add 34 miles, it was only necessary to dial zero three times, followed by dialing 4.