The foregoing illustration of the idiosyncrasies of mechanical construction offer a good example of why perpetual motion is not possible, viz., that no mechanism was ever made that would not consume a certain per cent of the power delivered to it, through friction and inertia. Of course, expert knowledge of the physical laws of mechanics allow of the application of force along the lines of least resistance, and it is with this feature that the new improvements in the Comptometer have to do. [Sidenote: _Felt’s improved method of carrying_] It would seem that the old carrying means could not be improved upon under the circumstances, but Felt conceived a means which gave more time for the storage of power for the carry and all kinds of time for its delivery, which decreased the power required for carrying by a very large per cent. The means he devised was a motor-type of carrying mechanism that could receive and deliver power at the same time without interference. Thus the full revolution of the lower wheel could be utilized in storage and the same amount of time could be consumed in delivery if necessary, but it was never required. This tremendous reduction in power required to turn the higher wheel in a carrying operation so decreased the resistance of turning the numeral wheels that the former means used to control the wheels during actuation was unsafe; that is, the old method of jabbing the stop detent between the pins of the numeral wheel to stop it was not dependable with the increased speed that the numeral wheels revolved, under the reduced resistance. 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. [Sidenote: _Gauging and controlling prime actuation_]