The reproduction of the patent drawings of the Stark machine
illustrated on the opposite page show a series of numeral wheels, each
provided with three sets of figures running from 1 to 9 and 0.
[Sidenote: _Description of Stark machine_]
Pivotally mounted upon the axis of the numeral wheels at each end
are sector gears E¹ and arms E⁴, in which are pivoted a square shaft
E, extended from one arm to the other across the face of the numeral
wheels. The shaft E, is claimed to be held in its normal position by a
spring so that a pawl, E², shiftably mounted on the shaft, designed to
ratchet or actuate the numeral wheels forward, may engage with any one
of the numeral wheel ratchets.
A bail marked D, is pivoted to standards A¹, of the frame of the
machine, and is provided with the two radial racks D³ which mesh with
the sector gears E¹. It may be conceived that the act of depressing
the bail D, will cause the actuating pawl E², to operate whichever
numeral wheel it engages the ratchet of.
The bail D, is held in its normal position by a spring D², and is
provided with nine keys or finger-pieces d, eight of which co-act with
the stepped plate G, to regulate the additive degree of rotation given
to the numeral wheels, while the ninth has a fixed relation with the
bail and the bail itself is stopped.
The keys d, marked from 1 to 8, are pivoted to the bail in such a
manner that their normal relation to the bail will allow them to pass
by the steps on the stepped plate G, when the bail is depressed by
the fixed No. 9 key. When, however, any one of the keys numbered from
1 to 8 is depressed, the lower end of the shank of the key will tilt
rearward, and, as the bail is depressed, offers a stop against the
respective step of the plate G, arranged in its path, thus stopping
further action of the actuating pawl E², but offering nothing to
prevent the continuation of the force of momentum set up in the numeral
wheels by the key action.
There was small use in stopping the action of the pawl E², if the
ratchet and numeral wheel, impelled by the pawl, could continue onward
under its momentum.
The carry of the tens transfer device is of the same order as that
described in the Pascal and Hill machines; that is, a one-step
ratchet-motion actuated by a cam lug or pin from the lower wheel. The
carry transfer device consists of the lever F, and pawl f⁴, acting on
the ratchet of the upper wheel which is operated by the cam lugs b⁵ of
the lower wheel acting on the arms f¹ and f³ of the lever F.
[Illustration: From the Robjohn Patent Drawings]
[Sidenote: _Inoperativeness of Stark machine_]
The machine shown in the Stark patent was provided with but one set of
keys, but the arrangement for shifting the driving ratchet pawl E²,
from one order to another, so that the action of the keys may rotate
any one of the numeral wheels, gave the machine greater capacity than
the single digit adders; but as with the Chapin machine, of what use
was the increase in capacity if the machine would not add correctly.
That is about all that may be said of the Stark machine, for since
there was no means provided by which the rotation of numeral wheels
could be controlled, it was merely a device for rotating numeral wheels
and was therefore lacking in the features that would give it a right to
the title of an adding machine.
[Sidenote: _Nine keys common to a plurality of orders_]
The nine-key scheme of the Stark invention, connectable to the
different orders, was old, and was first disclosed in the U. S. Patent
to O. L. Castle in 1857 (a machine operated by a clock-spring wound by
hand), but its use in either of these machines should not be construed
as holding anything in common with that found in some of the modern
recording adders. The Castle machine has not been illustrated because
it does not enter into the evolution of the modern machine.
The ancient Art, or the Art prior to the invention of Parmelee,
consisted of mechanism which could be controlled by friction devices,
or Geneva gear-lock devices, that were suitable to the slow-acting type
of manipulative means.
The first attempt at a positive control for a key-driven adding device
is found in a patent issued to W. Robjohn in 1872 (see illustration).
As will be noted, this machine was referred to in the foregoing
discussion as merely a single-digit adding machine, having the capacity
for adding but one column of digits at a time.