The U. S. Patent Office records show that one ambitious inventor,
Thomas Hill, in 1857 secured a patent on a multiple-order key-driven
calculating machine (see illustration), which he claimed as a new and
useful invention. The Hill patent, however, was the only one of that
class issued, until the first really operative modern machine was made
thirty years later, and affords a fine example by which the features
that were lacking in the make-up of a really operative machine of this
type may be brought out.
[Sidenote: _Description of the Hill machine_]
The illustrations of the Hill machine on the opposite page, reproduced
from the drawings of the patent, show two numeral wheels, each having
seven sets each of large and small figures running from 1 to 9 and
the cipher marked on their periphery. The large sets of figures are
arranged for addition or positive calculation, and the small figures
are arranged the reverse for subtraction or negative calculation. The
wheels are provided with means for the carry of the tens, very similar
to that found in the Pascal machine. Each of the two wheels shown are
provided with ratchet teeth which correspond in number with the number
of figures on the wheel.
Spring-pressed, hook-shaped ratchet pawls marked b, are arranged to be
in constant engagement with the numeral wheels. These pawls are each
pivotally mounted in the end of the levers marked E, which are pivoted
at the front end of the casing.
[Illustration: Hill Patent Drawings]
The levers E, are held in normal or upward position by springs f, at
the front of the machine. Above each of these levers E, are a series of
keys which protrude through the casing with their lower ends resting
on the levers. There are but six keys shown in the drawing, but the
specification claims that a complete set of nine keys may be supplied
for each lever.
The arrangement and spacing of the keys are such that the greater the
value of the key the nearer it is to the fulcrum or pivot of the lever
E. The length of the key stem under the head or button of each key is
gauged to allow depression of the key, the lever E and pawl b, far
enough to cause the numeral wheel to rotate as many numeral places as
the value marking on the key.
A back-stop pawl for the numeral wheels, marked p, is mounted on a
cross-rod at the top of the machine. But one of these pawls are shown,
the shaft and the pawl for the higher wheel being broken away to show
the device for transferring the tens to the higher wheel.
The transfer device for the carry of the tens is a lever arrangement
constructed from a tube F, mounted on the cross-rod m, with arms G and
H. Pivoted to the arm G, is a ratchet pawl i, and attached to the pawl
is a spring that serves to hold the pawl in engagement with the ratchet
of the higher-order numeral wheel, and at the same time, through its
attachment with the pawl, holds the lever arms G and H retracted as
shown in the drawing.
As the lower-order numeral wheel passes any one of its points from 9
to O, one of the teeth or cam lugs n, on the wheel will move the arm
H, of the transfer lever forward, causing the pawl i, to move the
higher-order wheel one step to register the accumulation of the tens.
The functions of the Hill mechanism would, perhaps, be practical if it
were not for the physical law that “bodies set in motion tend to remain
in motion.”
[Sidenote: _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.
[Sidenote: _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.
[Sidenote: _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.
[Sidenote: _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.
[Illustration]
[Illustration: Chapin Patent Drawings]
Lack of a proper descriptive term used to refer to an object, machine,
etc., oftentimes leads to the use of an erroneous term. To call the
Hill invention an adding machine is erroneous since it would not add
correctly. It is as great an error as it would be to refer to the
Langley aeroplane as a flying machine.
[Sidenote: _Hill machine merely adding mechanism, incomplete as
operative machine_]
When the Wright brothers added the element that was lacking in the
Langley plane, a real flying machine was produced. But without that
element the Langley plane was not a flying machine. Likewise, without
means for controlling the numeral wheels, the Hill invention was not an
adding machine. The only term that may be correctly applied to the Hill
invention is “adding mechanism,” which is broad enough to cover its
incompleteness. And yet many thousands of people who have seen the Hill
invention at the National Museum have probably carried away the idea
that the Hill invention was a perfectly good key-driven adding machine.
[Sidenote: _Chapin and Stark patents_]
Lest we leave unmentioned two machines that might be misconstrued to
hold some of the features of the Art, attention is called to patents
issued to G. W. Chapin in 1870 (see illustration on opposite page), and
A. Stark in 1884 (see illustration on page 32).