JI 



360 Dr. R. Hare on Improvements in the 



employed, and the platform is necessarily resorted to, the 

 cocks must be adjusted by an assistant. 



Fig. 5 repre- 

 sents a cask made 

 of boiler iron, 

 three-sixteenths of 

 an inch thick, so 

 as to resist an 

 enormous pres- 

 sure. The joints 

 are secured by 

 riveting, as in 

 constructing high 

 pressure boilers. 



This cask com- 

 municates with 

 the hydrant pipes, 

 so called, by which 

 our city is sup- 

 plied with water, 

 of which the pres- 

 sure varies from a 

 half to more than 

 two atmospheres, 

 say from seven to 

 thirty pounds per 

 square inch, ac- 

 cording to the 

 number and bore 

 of the cocks from 

 which the water 

 may be flowing 

 at the time for 

 the consumption 

 of the community. 

 Hence experi- 

 ments, while using 

 this head, are best 

 made towards bed-time, or between that time and sunrise. 

 The vessel is filled with water by opening a cock F on one side 

 of the pipe C, and allowing the air to escape through the valve- 

 cock B. Being thus supplied, the cock F closed, and a commu- 

 nication with a bell-glass, into which oxygen is proceeding from 

 a generating apparatus, being made by means of a flexible 

 leaden tube, on opening the valve- cock B and the cock E, the 

 water will run out and be replaced by gas from the bell. This 

 process being continued till the iron cask is sufficiently supplied 



