104- HYDRAULIC INVESTIGATIONS, 



IV. 



Hydraulic Investigations, subservient to an intended Croo- 

 nian Lecture on the Motion of the Shod* By Thomas 

 Young, M. D. For. Sec. K. S*. 



I. Of the Friction and Discharge of Fluids running in 

 Pipes, and of the Velocity of Rivers. 



Motion of JlJL AVING lately fixed on the discussion of the nature of 



fluids in flexi- inflammation, for the subject of an academical exercise, I 



pie clastic J 



tube». found it necessary to examine attentively the mechanical 



principles of the circulation of the blood, and to investigate 

 minutely and comprehensively the motion of fluids in pipes, 

 as affected by friction, the resistance occasioned by flexure, 

 the laws of the propagation of an impulse through the fluid 

 contained in an elastic tube, the magnitude of a pulsation 

 in different parts of a conical vessel, and the effect of a con- 

 traction advancing progressively through the length of a 

 given canal. The physiological application of the results 

 of these inquiries I shall have the honour of laying before 

 the Royal Society at a future time; but I have thought it 

 advisable to communicate, in a separate paper, such conclu- 

 sions, as may be interesting to some persons, who do not 

 concern themselves with disquisitions of a physiological na- ( 

 ture ; and 1 imagine it may be as agreeable to the Society, 

 that they should be submitted at present to their considera- 

 tion, as that they should be withheld until the time appoint- 

 ed for the delivery of the Croonian Lecture. 

 Dubuat's cal- It has been observed by the late Professor Robison, that 

 dilations agree t jj e com parison of the Chevalier Dubuat's calculations with 

 ment? Xpen " bis experiments is in all respects extremely satisfactory; 

 that it exhibits a beautiful specimen of the means of ex- 

 pressing the general result of an extensive series of obser- 

 vations in an analytical formula, and that it does honour to 

 the penetration, skill, and address of Mr. Dubuat, and of 



•Pbilos. Trans, for 1808, p. 164. 

 k Mr. 



