PHYSICAL AND LITERARY. 117 



^ards. But nothing more can poffibly; 

 be meant, than that the horfp lofes a$ 

 jnuch force as the {tone gains : And that, 

 ;<Yith refpecfl to the horfp, the effe^fl is th^ 

 fame, as if there was no ftone tied behin4 

 liim, but that he was pufhed back with a 

 force equal to that acquired by the ftone^ 

 The adiive force of the horfe's limbs preCr 

 fes forwards both the hprfe and the ftone ; 

 what is called the readlion of the ftone, 

 is not equal to the whole force exerted by 

 the horle j for then indeed there could be 

 no progreflion: It is only equal to what 

 is imprefTed upon the ftone. 



The equality of acSlion and rea^ion in 

 the cafe of prefTures, is to be underftood 

 in the fame manner. When a finger is 

 prelTed againft any body, the body is faici 

 Jo reaift upon the finger, as much as the 

 finger is made to ad upon the body. If 

 the weight of the body be fuftained by 

 the prelTure of the finger, there will be an 

 aflive refiftance from the power of gravi- 

 ty. And, if the figure of the body be vio- 

 lently kept in a bent or comprefled ftate, 

 there will be an adive refiftance from the 



caufe 



