The next machine that has any bearing on the key-driven Art of which
there is a record, is illustrated in a patent granted to C. G. Spalding
in 1884 (see illustration on opposite page). The Spalding invention,
like that of Bouchet, was provided with control for its primary
actuation and control for its secondary or carrying actuation.
[Sidenote: _Description of Spalding machine_]
Referring to the Spalding machine reproduced from the drawings of
his patent, the reader will note that in place of the units and tens
numeral wheels, a clock hand has been supplied, co-operating with a
dial graduated from 0 to 99, showing the figures 5, 10, 15, etc., to
95, for every five graduations.
Another similar hand or arrow and dial to register the hundreds is also
provided, having a capacity to register nineteen hundred. Attached to
the arrows, through a shaft connection at the back of the casing are
ratchet wheels, having respectively the same number of teeth as the
graduation of the dial to which each hand belongs.
Co-operating with the hundred-tooth ratchet of the units and tens
register hand is a ratchet and lever motion device (see Fig. 2) to turn
the arrow from one to nine points of the graduation of the dial. The
ratchet and lever motion device consists of the spring-pressed pawl E,
mounted on the lever arm D, engaging the hundred-tooth ratchet, the
link or push-rod F, the lever G, and its spring O. It will be noted
that a downward action of the lever G, will, through the rod F, cause
a like downward action of the lever D, causing the ratchet pawl E to
be drawn over the ratchet teeth. Upon the release of the lever G, the
spring O, will return it to its normal position and through the named
connecting parts, ratchet forward the arrow.
The normal position of the pawl E is jammed into the tooth of the
ratchet and against the bracket C, that forms the pivot support for
the pivot shaft of the arrow. This jammed or locked combination serves
to stop the momentum of the ratchet wheel at the end of the ratcheting
action, and holds the wheel and its arrow normally locked until the
lever G is again depressed.
The means for gauging the depression and additive degrees of action of
the lever G is produced through the slides or keys marked a, having
finger-pieces c, springs f, and pins e, bearing against the top of the
lever G, combined with what may be called a compensating lever marked K.
The specification of the patent states that the depression of a key
will depress the lever G and the free end will engage the bent end t,
of the compensating lever K, and rock its envolute curved arm M, upward
until it engages the pin e of the key, which will block further motion
of the parts.
The effectiveness of the construction shown for the lever K is open to
question.
[Sidenote: _Prime actuation of a carried wheel impossible in the
Spalding machine_]
The carry of the hundreds is accomplished by means of a one-step
ratchet device represented by the parts lever R, pawl T, spring P, and
operating pin g. When the hundred-tooth ratchet nears the end of its
revolution, the pin g, made fast therein, engages the free end of the
ratchet lever R, and depresses it; and as the hand attached to the
hundred-tooth ratchet wheel passes from 99 to 0 the pin g passes off
the end of the ratchet lever R, and the spring P retracts the lever
ratcheting the twenty-tooth wheel and its arrow forward one point so
that the arrow registers one point greater on the hundreds dial.
Although the Spalding means of control under carrying differed from
that of Bouchet in construction, its function was virtually the same
in that it locked the carried or higher wheel in such a manner as
to prevent the wheel from being operated by an ordinal set of key
mechanism.
And the control under key action would prevent a carry being delivered
to that order through the locked relation of the ratchet and pawl E.
[Illustration]