The accumulator mechanism of the Barbour machine, including the numeral
wheels and their devices for transferring the tens, is mounted in a
sliding carriage at the top of the machine (see Fig. 1), which may be
operated by the hand-knob.
[Sidenote: Description of Barbour Multiplier]
Extending through the bottom of the carriage are a series of pinions,
one for each ordinal numeral wheel, and connected thereto by a ratchet
and pawl action. The pinions are each so arranged as to be operative
with a gear rack beneath the carriage when the carriage is slid back
and forth.
Thus the wheels received action from one direction of the motion of the
carriage and remain idle during the movement in the other direction.
The degree of motion so received would, of course, depend upon the
number of teeth in the racks below encountered by the pinions.
The gear racks employed by Barbour were numerous, one being provided
for each multiple of the nine digits, arranged in groups constituting
nine sets mounted on the drums marked B (see Fig. 4). Each of these
sets contain nine mutilated gear racks, the arrangement of the teeth of
which serve as the multiples of the digit they represent.
The teeth of the racks representing the multiples of the digits were
arranged in groups of units and tens. For instance: 4 × 6 = 24, the
rack representing the multiple of 4 × 6 would have two gear teeth in
the tens place and four gear teeth in the units place, and likewise for
the eighty other combinations.
Adding the multiples of the digits by overlapping the orders was
accomplished by a very simple means, the arrangement of the racks being
such that as the carriage was moved from left to right the numeral
wheel pinions would move over the units rack teeth of a multiplying
rack of one order and the tens rack teeth of a multiplying rack in the
next lower order.
By close examination the reader will note from the drawings that the
lower one of the sets of multiplying gear racks shown on the drum B,
to the left in Fig. 4, is the series of one times the nine digits, the
next set or series of racks above are the multiplying racks for the
multiples of two, the lowest rack in that series having but two teeth,
the next higher rack four teeth, the next rack six and the next eight.
So far no multiple of two has amounted to more than a units ordinal
place, therefore these racks operate on a lower-order numeral wheel,
and are all placed to the right of the center on the drum B, but the
next rack above for adding the multiple of two times five requires that
one shall be added to a higher order, and is therefore placed on the
left side of the center of the drum.
Thus it will be noted that by reading the number of teeth on the right
of each rack as units and those on the left as tens, that running
anti-clockwise around the drum, each series of multiplying racks show
multiples of the digits from one to four, it being obvious that the
racks for adding the multiples of the higher digits are on the opposite
side of the drums.
From the layout of the racks it is also obvious that the starting or
normal position of the carriage would be with the numeral wheel pinions
of each order in the center of each drum, so that as the carriage is
moved to the right the units wheel will receive movement from the units
teeth of the rack on the units drum, while the tens wheel will receive
movement from the units teeth of the tens drum and the tens teeth of
the units drum, and so on with the higher wheels, as each numeral wheel
pinion except the units passes from the center of one drum to the
center of the next lower and engages such teeth as may be presented.
Each of the drums B are independently mounted on the pivot shaft C, and
are provided with the hand-operating setting-racks I and E, co-acting
with the gears R and D, to help in bringing the proper racks into
engageable positions with the pinions of the accumulator numeral or
total wheels.
The hand-knob G, Fig. 4, and the gears f, fast to a common shaft,
furnish a means for operating the whole series of drums when the right
multiple series of racks of each drum have been brought into position.
As an example of the operation of the Barbour calculator, let us assume
that 7894 is to be multiplied by 348. The first drum to the right would
be moved by its setting-racks until the series of multiplying racks for
adding the multiples of four are presented, the next higher drum to the
left would be set until the series of multiplying racks for adding the
multiples of nine were presented, the next higher drum would be set
for the multiples of eight, and the next higher drum, or the fourth to
the left, would be set for the multiples of seven. Then the hand-knob
G, first turned to register zero, may be shoved to the right, engaging
the pinions f with the gears D, and by turning the knob to register
(8), the first figure in the multiplier, the racks are then set ready
to move the numeral wheels to register as follows: The drum to the
right or the units drum has presented the multiplying rack for adding
the multiple of 8 × 4, thus it will present three teeth for the tens
wheel and two teeth for the units wheel. The tens drum presenting the
rack for adding the multiple of 8 × 9 will present seven teeth for the
hundreds wheel and two for the tens wheel. The hundreds drum presenting
the rack for adding the multiple of 8 × 8 will present six teeth for
the thousands wheel and four for the hundreds wheel.
[Illustration]
[Illustration: From Drawings of Bollee Patent No. 556,720]
The rack of the thousands drum representing the multiple of 8 × 7 will
present five teeth for the tens of thousands wheel and six for the
thousands wheel. Thus by sliding the carriage to the right one space,
the numeral wheel pinions will engage first the units teeth on one
drum, then the tens teeth on the next lower drum and cause the wheels
to register 63152. The operator, by turning the knob G to register (4),
the next figure of the multiplier, turns the drum so that a series of
multiplying racks representing multiples of 4 times each figure in the
multiplicand are presented, so that by sliding the carriage another
space to the right, the multiple of 4 × 7894 will be added to the
numeral wheels. The operator then turns the knob to register three and
moves the carriage one more space to the right, adding the multiple of
3 × 7894 to the wheels in the next higher ordinal series, resulting in
the answer of 2747112.
There are, of course, many questionable features about the construction
shown in the machine of the Barbour patent, but as a feature of
historic interest it is worthy of consideration, like many other
attempts in the early Art.