74 



PHYSIOLOGY OF THE CIRCULATION. 



some idea of the rate of increase in the lateral pres- 

 sure of a fluid under these circumstances. 



10 xp. 1. I took a small wooden vessel, holding 

 about three gallons of water, and fitted, horizontally, 

 to its lower part, a cylindrical tin pipe, three inch > 

 long and half an inch in diameter (Fig. 1). On the 



FIG. 1. 



a, The reservoir. 



/, The horizontal pipe communicating; through the minute aper- 

 tures, c c, with the interior of the vertical ul.iss ml>e, </. 



e e. The external orifiec of the horizontal pipe, of its full diameter. 

 ff, The same reduced in diameter fmrn .', to ', nf an inch. 

 ii it, Thr same still further reduced to ,', <>!'an inch. 



/i. Tin- hriiilit tn \\hirli tin' water mse in the ula^s tuhe when 

 the diameter of the external orifice was reduced toff. 



i, Its height at the time that the external oriliee was contracted 



upper surface of this pipe, ten small holes, each 

 about one twelfth of an inch in diameter, were made 

 at an equal distance from each other, so as to extend 

 along the whole length of the pipe, with the excep- 

 tion of half an inch at either end : over these aper- 

 tures an arched piece of tin was soldered, from the 

 centre of which projected upwards a short branch, 

 and into it was fitted, vertically, a glass tube, twenty 

 inches long and one quarter of an inch in diameter. 



