232 



THE BAROMETER. 



end is closed with the finger, the tube is inverted and 

 the mouth dipped into a vessel of mercury ; the finger 

 is then withdrawn. As long as the tube is kept 



., _xo 



-1 



___L Q 



FIG. 160 ( ^ real szee). 



FIG. 161 (i real size). 



inclined, so that the upper end is not more than 

 about 70 cm above the level of the mercury in the vessel, 



