LECT. III. 



EXPERIMENTS. 



Fig. 4. 



each other ; B has at a a brass plate perforated by holes, on 

 which the membrane submitted to experiment is placed ; c 

 is also furnished with 

 a plate perforated with 

 holes, which, when the 

 two cylinders B c are 

 united, as in the sub- 

 joined figure, fits accu- 

 rately on the membrane, 

 which is thus pressed be- 

 tween the two plates In 

 this condition it can only 

 yield to the greater pres- 

 sure exercised upon it fey 

 a liquid, denser than that 

 contained in the other 

 portion of the cylinder. 

 m w, o p are two tubes of 

 equal calibre : the first 

 communicates with the 

 receiver B ; the other, 

 with the receiver c. When we wish to use the instrument 

 we introduce the denser liquid into B, and fill the tube m n, 

 with it to a certain height, c is then filled with water by 

 plunging it in a vessel of this liquid. The two cylinders 

 are then fitted together under water, and the two receivers 

 pressed together by a vice, in order that the liquid con- 

 tained in c may not escape through the fissure of the join- 

 ing. We place the instrument on a level, and then put the 

 two liquids at of the scale s. With this instrument we 

 obtain at the same time the value both of the elevation and 

 of the depression of the two liquids, which gives a great 

 precision and much experimental facility, by thus doubling 

 the results. 



Double-action Endosmometer. 



