150 



PRESSURE INDICATOR. 



Fig. 33. 



B is the pipe forming the communication between the floating vessel and the 

 main on the outside of the valve, by which the opening is regulated. 



C is the rod, on the top of which the pencil is fixed. 



D is the revolving cylinder, divided into horizontal lines corresponding to 

 five-tenths of an inch, and into vertical lines corresponding to the revo- 

 lutions of the time-piece. 



