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PREFACE. 



lie know, that he docs not agree witli me in thinking the 

 common way of teaching Sir Ifaac's Aflronomy improper, 

 and adheres to the reahty of Projection and Gravitation ; and 

 beheves, that Motion begun by impulfe, in an unrefifting 

 medium, is eternal either by a vis infita in the body, or by 

 virtue of the impulfe. 



There is another Gentleman, Dr. Hope, ProfcfTor of Bo- 

 tany in the fame Univerfity, which he has enriched with 

 one of the beft Botanical gardens in Europe, to whom I am 

 much obliged for information concerning the Vegetable 

 Life ; and I have profited alfo by Converfation with Dr. 

 Black, Profeilbr of Chemiftry in the fame Univerfity, well 

 known for his eminence in that Art; and accordingly the 

 Reader will obferve, that I have argued much both from 

 the motions of the vegetable, and from the motions of the 

 fmall particles of matter with which Chemiftry is converfant, 

 to the great motions in the univerfe, believing that there is 

 an Analogy of fome kind or another betwixt all the motions 

 of this univerfe. 



