ON THI THEORY OP HYDRAULICS. 2pi 



It may be shown, by steps nearly similar to those by which the velocity of 

 the motions of waves is investigated, that a fluid which is contained in an 

 clastic pipe, and which receives an impulse at any part of the pipe, will 

 transmit its effects, with the same velocity, as a Avave would have in a reser- 

 voir, of that depth which measures the elasticity of the pipe, that is, with 

 half the velocity which a body would acquire, in falling from the height at 

 which a portion of the fluid, connected with the contents of the pipe, would 

 stand in a vertical tube. It is in this manner that the blood is transmitted, 

 by means of the impulse given to it by the heart through the bloodvessels; 

 the pulse moves on with great rapidity, the elastic force of the vessels being 

 considerably assisted by the temporary actions of the muscular coats of the 

 arteries, which cause a contraction more rapid than the dilatation ; while the 

 whole mass of the arterial blood continues, at the same time, to advance 

 with a much smaller velocity ; like the slow stream of a river, on the surface 

 of which undulations are continually propelled, with motions independent of 

 it5 own. 



