Hill machine at National Museum
Considerable unearned publicity has been given the Hill invention on account of the patent office model having been placed on exhibit in the National Museum at Washington. Judging from the outward appearance of this model, the arrangement of the keys in columns would seem to impart the impression that here was the foundation of the modern key-driven machine. The columnar principle used in the arrangement of the keys, however, is the only similarity.
Inoperativeness of Hill machine
The Hill invention, moreover, was lacking in the essential feature necessary to the make-up of such a machine, a lack that for thirty years held the ancient Art against the inroads of the modern Art that finally displaced it. The feature lacking was a means for controlling the action of the mechanism under the tremendously increased speed produced by the use of depressable keys as an actuating means.
Hill made no provision for overcoming the lightning-speed momentum that could be given the numeral wheels in his machine through manipulation of the keys, either from direct key-action or indirectly through the carry of the tens. Imagine the sudden whirl his numeral wheel would receive on a quick depression of a key and then consider that he provided no means for stopping these wheels; it is obvious that a correct result could not be obtained by the use of such mechanism. Some idea of what would take place in the Hill machine under manipulation by an operator may be conceived from the speed attained in the operation of the keys of the up-to-date modern key-driven machine.
High speed of key drive
Operators on key-driven machines oftentimes attain a speed of 550 key strokes a minute in multiplication. Let us presume that any one of these strokes may be a depression of a nine key. The depression and return, of course, represents a full stroke, but only half of the stroke would represent the time in which the wheel acts. Thus the numeral wheel would be turned nine of its ten points of rotation in an eleven hundredth (¹/₁₁₀₀) of a minute. That means only one-ninth of the time given to half of the key-stroke, or a ninety-nine hundredth (¹/₉₉₀₀) of a minute; a one hundred and sixty-fifth (¹/₁₆₅) part of a second for a carry to be effected.
Camera slow compared with carry of the tens
If you have ever watched a camera-shutter work on a twenty-fifth of a second exposure, which is the average time for a snap-shot with an ordinary camera, it will be interesting to know that these controlling devices of a key-driven machine must act in one-fifth the time in which the shutter allows the daylight to pass through the lens of the camera.
Think of it; a machine built with the idea of offering the possibility of such key manipulation and supplying nothing to overcome the tremendous momentum set up in the numeral wheels and their driving mechanism, unless perchance Hill thought the operator of his machine could, mentally, control the wheels against over-rotation.