The Parmelee Machine

First attempt to use depressable keys for adding was made in America

By referring to the illustration of the [Parmelee machine] reproduced from the drawings of the patent, the reader will notice that the patentee deviated from the established principle of using numeral wheels. In place of numeral wheels a long ratchet-toothed bar has been supplied, the flat faces of which are numbered progressively from the top to the bottom.

Description of Parmelee machine

As shown in [Fig. 2] of these drawings, a spring-pressed ratchet pawl marked k, engages the teeth of the ratchet or numeral bar. The pawl k, is pivoted to a lever-constructed device marked E, the plan of which is shown in [Fig. 3]. This lever device is pivoted and operated by the keys which are provided with arms d, so arranged that when any one of the keys is depressed the arm contacts with and operates the lever device and its pawl k to ratchet the numeral bar upwards.

Another spring-pressed ratchet pawl marked m ([see Fig. 2]) is mounted on the bottom of the casing and serves to hold the numeral bar from returning after a key-depression.

It will be noted from [Fig. 1] that the keys extend through the top of the casing in progressively varying heights. This variation is such as to allow the No. 1 key to ratchet up one tooth of the numeral bar, the No. 2 key two teeth, etc., progressively. By this method a limited column of digits could be added up by depressing the keys corresponding to the digits and the answer could be read from the lowest tooth of the numeral bar that protruded through the top of the casing.

It is evident that if the Parmelee machine was ever used to add with, the operator would have to use a pussyfoot key-stroke or the numeral bar would over-shoot and give an erroneous answer, as no provision was made to overcome the momentum that could be given the numeral bar in an adding action.

Foreign digit adders
Single digit adders lack capacity

The foreign machines of the key-driven type were made by V. Schilt, 1851; F. Arzberger, 1866; Stetner, 1882; Bagge, 1882; d’Azevedo, 1884; Petetin, 1885; Maq Meyer, 1886. These foreign machines, like that of Parmelee, according to M. le Colonel d’Ocagne, were limited to the capacity of adding a single column of digits at a time. That is, either a column of units or tens or hundreds, etc., at a time. Such machines, of course, required the adding first of all the units, and a note made of the total; then the machine must be cleared and the tens figure of the total, and hundreds, if there be one, must then be added or carried over to the tens column the same as adding single columns mentally.

On account of these machines having only a capacity for adding one order or column of digits, the unit value 9 was the greatest item that could be added at a time. Thus, if the overflow in adding the units column or any other column amounted to more than one place, it required a multiple of key-depressions to put it on the register. For example, suppose the sum of adding the units columns should be 982, it would require the depression of the 9-key ten times and then the 8-key to be struck, to put the 98 on the machine. This order of manipulation had to be repeated for each denominational column of figures.

Another method that could be used in the manipulation of these single-order or digit-adding machines was to set down the sum of each order as added with its units figure arranged relative to the order it represents the sum of, and then mentally add such sums (see example below) the same as you would set down the sums in multiplication and add them together.

Example of method that may be used with single column adder.

Such machines, of course, never became popular because of their limited capacity, which required many extra movements and caused mental strain without offering an increase in speed of calculation as compared with expert mental calculation. There were a number of patents issued in the United States on machines of this class which may well be named single digit adders.

Some early U.S. patents on single-digit adding machines

The machines of this type which were patented in the United States, preceding the first practical multiple order modern machine, were patented by D. D. Parmelee, 1850; W. Robjohn, 1872; D. Carroll, 1876; Borland & Hoffman, 1878; M. Bouchet, 1883; A. Stetner, 1883; Spalding, 1884; L. M. Swem, 1885 and 1886; P. T. Lindholm, 1886; and B. F. Smith, 1887. All of these machines varied in construction but not in principle. Some were really operative and others inoperative, but all lacked what may be termed useful capacity.

To those not familiar with the technical features of the key-driven calculating machine Art, it would seem that if a machine could be made to add one column of digits, it would require no great invention or ingenuity to arrange such mechanisms in a plurality of orders. But the impossibility of effecting such a combination without exercising a high degree of invention will become evident as the reader becomes familiar with the requirements, which are best illustrated through the errors made by those who tried to produce such a machine.

As stated, the first authentic knowledge we have of an actual machine for adding is extant in models made by Pascal in 1642, which were all multiple-order machines, and the same in general as that shown in the [illustration, page 10].

Calculating machines in use abroad for centuries

History shows that Europe and other foreign countries have been using calculating machines for centuries. Like that of Pascal’s, they were all multiple-order machines, and, although not key-driven, they were capable of adding a number of columns or items of six to eight places at once without the extra manipulation described as necessary with single-order digit adding machines. A number of such machines were made in the United States prior to the first practical multiple-order key-driven calculator.

First key-driven machines no improvement to the Art

This fact and the fact that the only operative key-driven machines made prior to 1887 were single-digit adders are significant proof that the backward step from such multiple-order machines to a single-order key-driven machine was from the lack of some unknown mechanical functions that would make a multiple-order key-driven calculator possible. There was a reason, and a good one, that kept the inventors of these single-order key-driven machines from turning their invention into a multiple-order key-driven machine.

It is folly to think that all these inventors never had the thought or wish to produce such a machine. It is more reasonable to believe there was not one of them who did not have the wish and who did not give deep thought to the subject. There is every reason to believe that some of them tried it, but there is no doubt that if they did it was a failure, or there would be evidence of it in some form.