The Preface. iii 



their great application aiid fagacity had 

 doubtlefs i?iade confiderable adva7ices in 

 the know/edge of the nature of Plaiits. 

 'This is the only fure way to 7neafure the 

 fever al quantities of nouriflxnent, which 

 Plants imbibe and perfpire, a7td thereby 

 to fee what influence the different flat es 

 of Air have on them. This is the likeliefl 

 7nethod to find out the Sap's velocity p , and 

 the force with which it is imbibed : As 

 aljo to eflimate the great power that 

 Nature exerts in extending and pufjoinv 

 forth her productions by the expanfion of 

 the Sap. 



About twenty years fince^ I made 

 feveral hcemaflatical Experiments on 

 Dogs \ and fix years afterwards re- 

 peated the fame on Horfes and other 

 Animals^ in order to find out the real 

 force of the blood in the Arteries \ fome 

 of which are mentioned in the third 

 chapter of this book : At whicb times I 



wifijed 



