G. B. Grant—New Calculating Machine. 283 
Addition and subtraction are of course worked directly, but 
By the tentative method we first set up our dividend 213525 
on the wheels by hand, or better, by transferring it from the 
pins. We then set the pins to our divisor 0657, by means of 
the inner or negative rows of figures, taking care to leave one 
zero in advance of it. Then place it up opposite the 135 of the 
dividend, and turn the handle, stopping at every turn to observe 
the dividend. It will continually decrease, and when you per- 
ceive that it is less than the divisor, you must stop and set the 
pins down one place before proceeding to the next figure. In 
the above case, the dividend after three turns will read 16425, 
and that being less than 65700 the first quotient figure is 3. 
The wheels will then read 00003016425, the quotient figure 
being recorded automatically by the machine on the upper 
wheels left vacant by the retreating dividend. 
To explain the automatic method we need to follow the pro- 
As 
ini ce 657, is added, the divisor decreases, and after 
147825 less than 65700, requiring us by the old method 
9999343 —2 to stop and set down for the next figure. And 
82125 it is necessary to 
9999348 —g3 mechanism to 
7 
1 
wepeeas 4 for that purpose. 
9 5 But it may be 
oe sense from, 16495 once more, that a negative 
———- _ number would result. And w 
ae achine, a negative number is exp . by 
its complement, its mechanical perception is an easy matter, since 
for such a case the upper wheels all read nine. | A snap, which 
will indicate when the last wheel stops on nine, will answer 
our purpose, and warn us that a mistake of one turn has been 
