Carrying and Printing
Carrying a 1 from one column to another posed a problem not only for Burroughs, but for others struggling to create similar machines. In order to facilitate carrying, the Burroughs adding machine goes through the following process:
The movement of the recording pinion (g), referred to in the addition process outlined in Step by Step, is effected by the pinion on its right. When the pinion to the right passes from nine to zero, a lug on that pinion releases a lever which holds a stop in place. This stop, when in place, restricts the movement of the rack (d). When the stop is removed the corresponding rack (d) will rise, turning one additional tooth in recording pinion (g) in order to accomplish the carrying operation. The lug on the pinion to the right of our recording pinion (g) returns to its normal position and resets the stop during the next forward motion of the operating lever.
By means of a hammer positioned at the rear of each one, the typefaces are banged against the spool of paper which has been threaded through the back of the machine. An ink ribbon stands between the typefaces and the paper, and the swinging motion of the hammers causes each typeface to leave ink imprints on the paper ribbon. The printing hammers are operated by springs whose movement is triggered at the last moment of the forward movement of the operating lever. It is at this moment that the printing mentioned in Step by Step occurs. The printing hammers are connected in such a manner that not only those that correspond to the depressed racks, but all those located to the right of the highest figure struck, are released at this point.
This realizes Burroughs' goal of printing a zero to hold the place of each lower column not containing a depressed key, and is necessary given that each column contains only digits one through nine. The printer spitting out each sum is located on the rear of the Burroughs Registering Accountant, making it difficult for our clerk to see what is printing. If he wants to view what is printed, he has to lift a carriage on the rear of the machine. For this reason, the Burroughs machines were called “blind” printers.