VOSS 
Moving’ Forces 255 
The quantity of moving force therefore, is, on 
one side m.AD, balanced on the other side by 
n.-AB+o.AC ; the moving force of each string 
being as the weight suspended to it multiplied 
into the space, through which it has moved. 
So that in this case, where the parallelogram 
is right angled, the moving forces m the dif: 
ferent directions are as the squares of the 
diagonal and the respective sides of the 
parallelogram. x 
When BAC is not a right ol let sp 
parallelogram be completed, and the weights 
suspended as hefore, and draw DF and DG 
(fig. 23) perpendiculars to AB and AC. «If 
the weights be set in motion, the point of 
junction of the strings will move in the direc- 
tion AD, and when that point has arrived at 
D, the. weights m, n, and o, will have moved 
through the spaces AD, AF, and AG re- 
spectively. The moving force, therefore, is 
on one side m.AD balanced by nw. AF'+0.AG 
on the other side ; or the moving forces in the 
different directions are réspectively as the 
square of AD, the rectangle AB. AF, and 
the rectangle AC.AG. 
This conclusion, however, involves the ge0- 
metrical proposition, that the square of AD i is 
equal to the sum of the rectangles AB. AF 
and AC. AG, a property of the triangle which 
