X 34 ESSAYS and OBSERVATIONS 



body may be pufiied or drawn to oppo- 

 fite (ides, by two contrary external forces: 

 In which cafe, if they are equal, the body 

 will remain at reft ; if unequal, it will be 

 moved to one fide, by the difference of the 

 two forces. Thus, every part of a flag- 

 Viating fluid is prefTed equally in every 

 direction. But if a body adlively tend to 

 one fide, it cannot adively tend to the o- 

 ther at the fame time, that being a 

 contradidlion in terms. And, in fadt, we 

 fhall find it impofUble to make two fuch 

 efforts in our own bodies, to move them 

 'wholly to two oppolite fides. This being 

 granted, it follows, that if the waters of 

 the fea gravitate towards the earth by an 

 a(5live force, they cannot, at the fame 

 time, gravitate by their own activity to- 

 wards the moon, fo as to produce the 

 tides. And, therefore, the gravitation in 

 one or both cafes is owing to an external 

 influence. The fame argument, if it fhall 

 be found conclufive, may be applied to 

 the attraction of the moon towards the 

 earth and fun, in the conjundions, and 



other 



