ON THE CONSERVATION OF FORCE 



193 



the individual teeth, and one after the other of which is 

 put in activity in the degree in which the tooth in question 

 seizes or is seized by the adjacent pinion. Take, for in- 

 stance, the crabwinch, represented in FIG. 93. Suppose the 

 pinion on the axis of the barrel of the winch has twelve 



FIG. 93 



teeth, and the toothed-wheel, H H, seventy-two teeth, that 

 is six times as many as the former. The winch must now 

 be turned round six times before the toothed-wheel, H, and 

 the barrel, D, have made one turn, and before the rope which 

 raises the load has been lifted by a length equal to the cir- 

 cumference of the barrel. The workman thus requires six 

 times the time, though to be sure only one-sixth of the exer- 

 tion, which he would have to use if the handle were directly 

 applied to the barrel, D. In all these machines, and parts of 

 machines, we find it confirmed that in proportion as the 

 velocity of the motion increases its power diminishes, and 

 that when the power increases the velocity diminishes, but 

 that the amount of work is never thereby increased, 

 ^c VOL. xxx G 



