Origin of modern calculating machines

by J. A. V. Turck

Each of the trigger latches are provided with a laterally extending lug 93, formed on their lower arm, and each lug overlaps the back of the lower arm of the adjacent trigger latch to the right of it, so that if any trigger latch should be operated so as to extricate it from the notch 50 of its printing hammer, its overlapping lug 93, would cause a like action of the trigger latch to the right of that, and so on; thus releasing all the trigger latches to the right of the latch originally released. Such releasing, of course, allowed the printing-hammers 87, to spring forward in all the orders so affected.

The long-stop actuating lever marked 16, corresponds with the lever G of the Felt key-driven calculator shown in a preceding chapter, and performs the same function as the rock bars L of the first Felt recorder patent. These stop levers 16 are pivoted at 17, and are provided with rear arms 86, extending upward with their ends opposite the lateral extending lug 93, of the trigger latch, which corresponds to the order of keys which the lever 16 serves.

In the rear upwardly-extending end of each of these levers 16, an adjusting screw 91, is provided as a tappet for tripping the trigger latch corresponding to its order.

From the above-described combination of mechanism, it may be seen that if a key in any order is depressed, it will, as it comes in contact with the stop lever 16, not only cause the adding mechanism to be stopped through the stop 19, but it will also, through its rear arm 86, cause the trigger latch of its order to trip, and likewise all the trigger latches and printing-hammers to the right, thus printing the figure presented on the printing sector in the order in which the key was operated and the ciphers in the orders to the right in case the keys in the order to the right have not previously been operated.

The individual presentation of the type figures upon key depression, except for the ciphers which were normally presented for printing, required that in striking the keys, to give correct recording of the items, the operation must be from right to left. That is, for example, if the item to be added was $740.85, the operator would depress the (5) key in the units cents column, the (8) key in the tens of cents column; the cipher in the units dollars column would be omitted, the (4) key in the tens of dollars, and the (7) key in the hundreds of dollars column would be struck.

The printing hammers were provided with means for resetting after being tripped in the recording action. This means is connected with the paper shift-lever, so that as the paper was shifted or fed upward, ready for recording the next item, the printing-hammers were all reset and latched on their respective trigger latches, ready for a new item.

Fixed to the shaft 97, on which the printing-hammers are pivoted, is a bail, marked 98, part of which is shown in the drawing, the horizontal bar of which normally lies under and out of the way of the hammers as they plunge forward in printing. And attached to the right-hand end of the shaft 97, is a crank arm connected by a link to the paper-shift hand-lever, which may be seen on the right in the [photo reproduction of the machine]. This connection is arranged so that depressing the lever causes the shaft 97 to rock the bail 98 rearward, thus picking up any tripped printing-hammers and relatching them.

The totals had to be printed, as in the first-described Felt recorder, by depressing a key corresponding in value to the figure showing on the wheel in each order.

Felt principle of printing adopted by all manufacturers of recorders

The principle involved in the individual hammer-blow, combined with the ordinal type sector for recording in a recording-adder was new, and was the feature that has made the adding-recording machine of today possible, as is well in evidence by the presence of this combination in all the recorders that have been made by the successful manufacturers of listing or recording-adding and calculating machines. Some manufacturers have substituted a vertical moving type bar for the pivoted sector, but the scheme is the same, as the purpose is to get the arrangement of the type in columnar order, and does not change the fundamental features of the combination which furnished the practical means for the individual type impression.