178 BENJ. PIKE'S, JR., DESCRIPTIVE CATALOGUE. 



m, to A, so that it shall descend, the exact quantity of 

 matter moved will be ascertained, for it will be A added to 

 B, added to m, added to 2 oz. 



In order to avoid troublesome computations in adjusting 

 the quantities of matter moved, and the moving force, one- 

 quarter of an ounce is assumed as a standard weight of 

 convenient magnitude, to which all others are referred ; this 

 weight is called m. Now the inertia of the wheel, being 2f 

 oz., will be denoted by 11 m j A and B, the pieces or boxes 

 to which the different weights are applied, are each, together 

 with the hooks by which they are suspended, equal 1^ oz. 

 or 6 m. We have a variety of different weights, some of 

 which are equivalent to 4m, others to 2 m, some equal m, 

 and others to aliquot parts thereof. 



If then we apply 19 m to each of the pieces, A B, these, 

 with those pieces, will each be equal 25 m, balancing them- 

 selves, and the whole mass will be 50 m, which being added 

 to II m, the inertia of the wheels, the whole mass will be 

 61 m j now add m to both A and B, and the whole mass 

 will be 63 m, perfectly in equilibrio and movable by the least 

 weight, added to either, setting aside the effect of friction, 

 in the same manner precisely as if the same weight or force 

 were applied to communicate motion to the mass 63 m, ex- 

 isting in a free space and without gravity. 



Of the moving force. As the natural weight,, or gravity, 

 of any given substance is constant, and the exact quantity 

 easily estimated, we shall apply a weight as a moving force ; 

 thus, when the system consists of a mass equal 63 m, I 

 apply a weight, m, to A, and it communicates motion to the 

 whole system ; the whole quantity of matter moved is 64 

 m; the moving force m, this gives us the force which ac- 

 celerates the descent of A, being m, or | part of the 

 accelerated force, by which the bodies descend freely to the 

 earth. 



You see by this example, that the moving force may be 

 altered without altering the mass moved ; for, suppose the 

 three weights m, two of which are placed on A and one on 

 B, be removed, then A will balance B. 



Now place the weights 3 m on A, and the moving force 

 will be 3 m, and the mass moved 64 as before, and the force 

 which accelerates the descent of A equal g|jj|. 



To make the moving force 2m, remove the three weights 

 m, A and B will balance one another, and the whole weight 



