ii PREFACE. 
purfuant to ' the Will of the late Lady 
Sadleir *. 
The Foundation of my Scheme is laid upon. 
thofe Hints which Sir Ifaac Newton has given, 
us in the Queries at the End of his incompa- 
rable Book of Op ticks ; together with what 
Dr. Pemberton has faid in his very learned 
Introduction to Cotoper on the Mufcles. How 
well it is executed is mofl humbly fubmitted 
. to my Superiors. I do not know that I have 
advanced any thing inconfiflent with true Phi- 
lofophy ; or to any of the known Laws of the 
animal Oeconomy. I have the Satisfaction to 
fee , in the fecond V ilume of the late Dr. 
Defaguliers’j experimental Philofophy §, that 
he approved of what I had formerly pub- 
lifloed , beyond all other Accounts of Mufcular 
Motion ; and I muft confefs , that meeting 
with Countenance from fo good a fudge gave 
me great Encouragement to purfue the En- 
quiry. 
* Whofe firfl Husband was Dr. Croon e, and at his Requeji thefe 
‘Lectures were founded. 
% 393 ' 
THE 
