2 
Dr. Young’s Lecture on the Functions 
skin of an animal has no power of generating an acid, or an 
alkali, to neutralise the action of an alkaline or an acid caustic, 
and therefore its texture is destroyed by the chemical attrac- 
tion of such an agent, when it comes into contact with it. As 
far, therefore, as the functions of animal life depend on the 
locomotions of the solids or fluids, those functions must be 
capable of being illustrated by the consideration of the me- 
chanical laws of moving bodies ; these laws being fully 
adequate to the explanation of the connexion between the 
motive powers, which are employed in the system, and the 
immediate effects, which they are capable of producing, in the 
solids or fluids of the body : and it is obvious, that the inquiry, 
in what manner, and in what degree, the circulation of the 
blood depends on the muscular and elastic powers of the 
heart and of the arteries, supposing the nature of those powers 
to be known, must become simply a question belonging to the 
most refined departments of the theory of hydraulics. 
In examining the functions of the heart and arteries, I shall 
inquire, in the first place, upon the grounds of the hydraulic 
investigations which I have already submitted to the Royal 
Society, what would be the nature of the circulation of the 
blood, if the whole of the veins and arteries were invariable 
in their dimensions, like tubes of glass or of bone ; in the se- 
cond place, in what manner the pulse would be transmitted 
from the heart through the arteries, if they were merely 
elastic tubes ; and in the third place, what actions we can with 
propriety attribute to the muscular coats of the arteries them- 
selves. I shall lastly add some observations on the disturb- 
ances of these motions, which may be supposed to occur in 
different kinds of inflammations and of fevers. 
