XLiv.J REMARKS ON THE HISTORY OF SCIENCE. 227 



Equal velocities are those which keep at the same distance of velocity: 

 when moving in the same direction on the same line or on 

 parallel lines. 



Equal times are those in which equal velocities traverse equal of time : 

 spaces. 



Equal forces are those which produce equal velocities in equal of force : 

 times. Or (what is a corollary from this), equal forces are those 

 which, when acting in opposite directions, neutralize each 

 other. 



Equal resistances are those which neutralize equal forces. of resist- 



Equal quantities of energy are those which overcome equal ^?*^® " 

 resistances through equal spaces. 



Q 2 



