rg10] BRIEFER ARTICLES 215 
(F), the beam A is caused to revolve until checked by the stop g’. As 
the end of A moves upward it carries with it the flange /, which strikes the 
Fic. 3 
handle of the stopcock and pushes it upward, thus opening the passage 
from the water supply through e, c, and a into 6’. The stop g’ is so 
located that b does not rise to quite so high a level as 6’, and the mercury 
