440 Sir J. F. W. Herschel on a Machine for resolving; Sfc. 



slider is firmly screwed on the face of the wheel, so as to revolve 

 with it. The distance between the axes f and B of these wheels 

 being changeable a re-entering string cannot be used, but it must, 

 after making a complete circumvolution of both, be fastened off 

 at each of its extremities to pegs, and brought by them into the 

 requisite state of tension. The rotation of cd will thus be trans- 

 ferred to ab, increased or diminished in any ratio according to the 

 ratio of the diameters of the wheels c d and a b, which must be 

 adjusted accordingly. It is evident that this construction accom- 

 plishes the end in question, which might indeed be accomplished 

 without the use of the wheels cd, c d, were it not necessary to 

 allow the center B completely to attain and even pass across C. 

 It is very likely that other and still simpler modes of accomplishing 

 the same object will suggest themselves to others. 



