ricscarclt Lahoratory of the Boycd College of Pliysicicms. 535 



about half an iiicli in length. This is the only means of com- 

 munication between the two reservoir chambers. Between the 

 lower chamber and the lower part of the steam chamber runs 

 a piece of half-inch tubing (b) on which is a stopcock. From 



Fig. 15. 



{a) Steam chamber ; (5) reservoir ; (c) water gauge ; {d) air pipe ; {e) orifice 

 for filling reservoir ; (/) communicating tube between two chambers ; {g) 

 copper bottom ; {h) rest for can. 



the lower chamber there is also a tube (g) running up the 

 outside of the cylinder through which air can gain access. 

 Attached to the upper chamber is a glass water gauge Qi), and 

 at the top in the middle is a supply opening. This is closed 

 by a levered screw cap (/), lined with india-rubber, in ordei* 

 that the joint may be perfectly air-tight. 



To set this to work, close the tap, cutting off communication 

 with the steam chamber; screw off the cap and fill up the 

 reservoir with water ; screw on the cap firmly, then open the 

 tap between the two chambers ; water immediately escapes 

 from the one into the other until it rises to the level of the 

 lower end of the pipe in the false bottom (Fig. 15) ; as soon as it 

 VOL. IX. 2 N 



