APPENDIX. 



383 



difficulty be made by joining together india-rubber 

 tubing by means of three-way glass tubes. 

 Clamps are placed upon the straight tubes c, c', c", 

 and the dilated tubes along the same line are stuffed 

 with sponge, until on closing the clamps and pump- 

 ing steadily, a mean pressure of two or three inches 

 of mercury is obtained in the arterial tube, 



Fia. 8. 



The arterial tube P is connected with an india-rubber 

 bag ; from the opposite end of which a tube passes 

 to a vessel full of water. The bag has two valves, 

 one at each end, opening in the same direction, 

 so that when it is compressed with the hand the 

 water it contains is driven onwards through the 

 arterial tube, and on its dilating water is drawn 

 up from the vessel. 



