326 
NATURE 
[Aug. 21, 1873 
the lid of the box being removed. It is constructed 
chiefly of a brass plate, A, furnished with eight slots, as 
shown ; directly under these slots are mounted eight 
drums, each having nine elongated cog teeth of succes- 
sively decreasing length ; over each drum, and between 
it and the slot,{is mounted a square shaft, on which slides 
a pinion wheel so as to catch any number of teeth on the 
drum, Each of these pinion wheels is moved by a but- 
ton, a, of which there is one in each slot, the figures at 
the sides of the slots showing the proper position of each 
button a, for any work to be performed by the in- 
strument. 
The cogged drums gear by bevil wheels with a long 
horizontal shaft, which is also in gear with the vertical 
shaft moved by the handle 6, by which the instrument is 
worked. B is a moveable brass plate, which can turn and 
slide on a round bar-hinge at the back; in this plate 
there are sixteen holes, c, under each of which is a moveable 
disc numbered from o to 9, and arranged so that any one 
figure of each disc may be brought under its correspond- 
ing hole ¢, These discs have bevil wheels which gear 
with bevil wheels on the before-mentioned square shafts. 
The moveable plate B is also furnished with the holes d, 
having discs numbered from 0 to 9 underneath, and are 
for showing the number of turns of the handle, giving by 
this means the quotient in division, and showing the mul- 
tiplier in multiplication. The knobs C and D are for 
bringing the figures under the holes ¢ and @ to zero before 
commencing an operation, and the knob E is for setting 
the instrument to work addition and multiplication, or 
subtraction and division. F is a small slate for memo- 
randa. ’ 
Before further describing the working of the machine, 
we would remark that, if the knob E be placed at Add‘, 
each turn of the handle will carfy the figures marked by 
the buttons a, under the indicator-holes ¢, or add them 
to the figures already under the holes ¢, while if the 
knob be placed at Sub", each turn of the handle will 
subtract from the figures under the holes c, the numbers 
marked by the buttons a, 
Such being the general construction and principle of 
the machine, we will now proceed to give an example of 
its operation for multiplication, the operations for addi- 
tion and subtraction being sufficiently explained in the 
preceding paragraph, 
Thus, to multiply 76847235 
by 6583 
Mark the multiplicand on the plate A by the buttons 2, 
as shown in the illustration ; set the knob E at Add® and 
Mulp", then turn the handle 4 three times for the unit 
fizure of the multiplier, and three times the multiplicand, 
viz. 230541705, willappearunder the holes cin the moveable 
plate B ; this plate must now be raised, and moved one 
figure or station to the right, and the handle turned eight 
times for the second figure of the multiplier, and 
oc ° ° ° 
B 
ie 
SUB" &DIVS 
i) 
—- , 
-9-9-9-0-6. 
2G) © @* G+ Grae 
O-wWUPnOVNeo 
c 
-@->: 
° (e} 
82 62 
Su 84 
ee 2 9 9 9 r) 9 
8 sou 8 8 8 8 8 At 
arz. 7 7 my 7 7 7 A 
ey? 6 6 6 6 6 6 “ 
5 5 5 5 6 6 5 
* 4 420 + 4 4 a ° 
3 3 z 3 3 s<qja 3 3 
2 2 2 2 243 2 2 
’ 1 1 1 ' ' ' 
C) o o rt o 0 r) 
Colmar’s Arithmometer 
6378320505 will appear under the holes c; move the 
plate B again to the right, and turn the handle five times 
for the third figure of the multiplier, and 44801938005 
will be brought under the holes ¢; and finally, by moving 
the plate B once more to the right, and turning the 
handle six times for the last figure of the multiplier, the 
total product, 505885348005, will appear under the holes 
c, and the figures of the multiplier, viz. 6583, will appear 
in the holes @. 
In division the operation is as simple as for multiplica- 
tion, and is performed as follows: thus, to divide 
414591904 by 4768, set up the dividend on the plate B, 
and the divisor on the plate A, commencing with the unit 
figure in each case to the right hand ; place the knob E 
at Sub" and Div", and move the plate B to the right until 
the second figure (from the left) of the dividend is over 
the first figure (4) of the divisor; turn the handle eight 
times, and 8 will appear in the quotient holes d, and will 
give the first figure of the quotient, while the dividend 
will now show 33151904, having been reduced by eight 
times the divisor, as in ordinary arithmetic ; move the 
plate B one place to the left, and turn the handle six times 
for the second figure of the quotient, and the dividend 
will be further reduced by six times the divisor, and will 
mark 4543904; again move the plate, and turn the 
handle nine times, and after moving the plate B, and 
turning the handle five times and three times respectively, 
the holes ¢ will all show noughts, and the quotient holes @ 
will show 86953, which is the quotient required ; if there 
had been any remainder, it would have appeared in the 
holes ¢, 
Although by the ordinary limits of the machine a pro- 
duct of 16 places of figures and a quotient of 9 places of 
figures only can be obtained, yet by an intermediate re- 
cord by the operator these limits may be virtually doubled 
for multiplication ; while for division, provided the divisor 
does not exceed eight places of figures, the dividend and 
the quotient may be unlimited. ; 
The use of the arithmometer in actuarial and other cal- 
culations has been shown in the papers read by Major- 
General Hannyngton and Mr, Peter Gray, F.R.A.S., 
F.R.M.S., respectively at the Institute of Actuaries (see 
the Journal of the Institute of Actuaries, p. 224, vol. xvi., 
and p. 249, vol. xvii.); and Mr. Thomas T. P. Bruce 
Warren, in a paper read before the Society of Telegraph 
Engineers, has shown the application of the instrument 
to electrical computations. 
The Arithmometer is now, we believe, used in many 
Government Offices, in nearly all the Life Insurance 
Offices in England, in several Observatories; Sir W. 
Thompson, Prof. Tait, Prof. Galbraith, and Dr, Ball, 
also use them in the Universities and Colleges with which 
they are respectively connected. ; 
The instrument canbe seen, and all information ob- 
tained, of Mr. W. A. Gilbee, of 4, South Street, Finsbury, 
who, we understand, is sele agent for the Arithmometer; 
