ELECTRICAL UNITS OF MEASUREMENT. 99 



absolute system, and is therefore T~ 2 . Equally 

 puzzling and curious is a velocity to the fourth 

 power for the reckoning of force, which we have 

 next to consider. 



The universal-gravitation reckoning of force, 

 which we shall see is by the fourth power of a 

 linear velocity, may be explained as follows. Find 

 the velocity with which a particle of matter must 

 be projected, to revolve in a circle round an equal 

 particle fixed at such a distance from it as to 

 attract it with a force equal to the given force. 

 The fourth power of this velocity is the number 

 which measures the force. Sixteen times the force 

 will give double the velocity ; eighty-one times 

 the force will give three times the velocity, and 

 so on. 



Now if I were to say that the weight of that 

 piece of chalk is the fourth power of twenty miles 

 an hour, I should be considered fit, not for this 

 place, but for a place where people who have 

 lost their senses are taken care of. I suppose 

 almost every one present would think it simple 

 idiocy if I were to say that the weight of that 



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