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. [Sidenote: _Foreign digit adders_] [Sidenote: _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.