86 The Arithmometer. 



One notable feature is this, that should a mistake be 

 made in the number of revolutions of the handle, it may 

 be detected by a glance at the quotient discs on the 

 completion of the operation, and at once remedied by a 

 single motion of the handle, the slide, and if necessary 

 the regulator. 



Should a number of products having a common factor 

 be needed, they can be similarly obtained without involving 

 the necessity of effacing and recommencing. We simply 

 modify the multiplier as it is exhibited in the quotient 

 discs, and the result is correspondingly modified by the 

 action of the mechanism. In this way, the following set 

 of results was obtained, the time occupied being less than. 

 2 minutes : 



323,457 



X 



317 = 



102,535,869 



X 



429 = 



138,763,053 



X 



1,749 = 



565,726,293 



X 



2,438 = 



788,588,166 



X 



196 = 



63,397,572 



X 



12,198 = 



3,945,528,486 



X 



144 = 



46,577,808 



In the corresponding case of a series of quotients having 

 a common divisor, the reciprocal of the divisor is set on, 

 and we proceed as in multiplication. 



One of the most important properties of the arithmometer, 

 is its power of accumulating results. If the result figures 

 instead of being at zero at the commencement of a 

 multiplication, be set at any particular number, at the 

 close of that multiplication they will exhibit the sum of 

 that number and the product obtained. Thus the sum- 

 mation of a series of products is rapidly effected. Nay 

 more, should any of the products be preceded by the 

 negative sign, that circumstance can be provided for by 

 setting the regulator E at division, while obtaining those 

 products. Thus, the algebraical sum of a series of products 

 is obtained at one continuous operation. 



As an example of this accumulation of results, I may 

 refer to the subjoined calculations, which actually occurred 

 in determining the capacity of one of our large reservoirs. 

 The figures in the right hand column represent the capacity 

 of the reservoir, for various depths of water. The first 

 result was obtained by multiplying the first number in the 

 left hand column 12, by the common multiplier 653,400, 

 the second by multiplying "52 by 653,400, and adding the 

 product to the first result, and so on. The time required 



