Again, the feature of time was at issue. The wheels could be whirled at tremendous speed or at a very slow speed. A sudden jab at a key with the finger sent the numeral wheels kiting ahead of the rest of the mechanism so that the detent could not be depended upon to enter between the right pins, which would result in erroneous calculation.
In the new machine, we find that to overcome this unevenness of action, Felt reversed the ratchet action of the denomination actuators, so that no wheel action occurred on their down-stroke under the action of the keys, but on the upstroke of the actuators the numeral wheels were turned by the power of the actuator springs stored by the key depression, thus giving an even set rotating action that could not be forced and that could be controlled by a stop detent.
As the timing of this stop-action was coincident with the stopping of the actuators on their upstroke, the actuator was used to perform this function in combination with a detent device that could be released from the wheel independent of the actuators to allow a carry to be delivered.
Gauging and controlling prime actuation
A feature worthy of note connected with this change is displayed in the method in which Felt overcame the timing of the stop action of the actuators in the downward action they received from the keys, which would have been as hard to control as it was to control the wheels under direct key action.
Alternating stop scheme
The scheme he devised gave more than double the time to perform the function of intercepting the lightning action with which the actuators moved under a quick key-stroke. The scheme shows a dual alternating stop-action constructed by the use of two stops acting at different levels and co-acting alternately with five equi-spaced stop-shoulders on the front end of the actuators, which were also arranged in different levels.
The two stops were actuated by the keys in a similar manner to the single stop which co-operated with the pins of the wheel in the old “Comptometer,” except that the odd keys operated one stop while the even keys operated the other.
Thus in the new “Comptometer” the (1) key acted to throw the higher level stop into the path of the lowest stop-shoulder on the actuator, and the (2) key acted to throw the lower level stop into the path of the same stop-shoulder on the actuator. In the same manner the (3) and (4) keys caused the odd and even stops to engage the next higher stop-shoulder on the actuator and so on with the rest of the keys.
As the spacing was doubled by the use of but five stop-shoulders, the stops were allowed double the time for entry between the stop-shoulders plus the space that the pin occupied as compared with former method, which was considerably more than double the time allowed for the same function in the old machine.