To His '%Jery TDear Friend 



DOCTOR ARGENT 



the excellent 

 and accomplished PRESIDENT of THE ROYAL 

 COLLEGE of PHYSICIANS, and to other learned 

 Physicians, his esteemed Colleagues. 



I have already and repeatedly presented you, my learned 

 friends, with my new views of the motion and function of the 

 heart, in my anatomical lectures; but having now for nine 

 years and more confirmed these views by multiplied demonstra- 

 tions in your presence, illustrated them by arguments, and 

 freed them from the objections of the most learned and skilful 

 anatomists, I at length yield to the requests, I might say en- 

 treaties, of many, and here present them for general considera- 

 tion in this treatise. 



Were not the work indeed presented through you, my learned 

 friends, I should scarce hope that it could come out scatheless 

 and complete; for you have in general been the faithful witnesses 

 of almost all the instances from which I have either collected 

 the truth or confuted error; you have seen my dissections, and 

 at my demonstrations of all that I maintain to be objects of 

 sense, you have been accustomed to stand by and bear me out 

 with your testimony. And as this book alone declares the blood 

 to course and revolve by a new route, very different from the 

 ancient and beaten pathway trodden for so many ages, and 

 illustrated by such a host of learned and distinguished men, I 

 was greatly afraid lest I might be charged with presumption did 



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