330 



Economy of Fuel. 



ney, and insert a pipe connected with a proper air chamber, or drum, 

 of sheet iron through which the gas might be made to pass and again 

 be returned to the flue above the intercepting partition. The plan 

 actually adopted, as the most simple, was to cover the top of the flue 

 from which the gas originally escaped, with a board laid in mortar 

 over the top of the chimney, and when the hot air had traversed the 

 drum, to turn it into another flue which remained open at the top, but 

 closed at bottom, except a single aperture for the admission of a pipe 

 from the drum. The arrangement is seen in the accompanying fig- 

 ure, where F is the flue coming from the basement ; E is the six inch 



pipe which receives the gas ; D is the drum three feet and nine 

 inches high by two feet in diameter, from which proceeds the pipe 

 e for the exit of the gas, into the chimney at P, through the brick 

 wall with which the fire place has been closed. F' is the flue 

 through which the gas finally makes its escape into the open air ; t 

 is a thermometer with its bulb descending through a hole perforated 

 in the sheet iron, to the center of the pipe, and near where it comes 

 out of the flue. This is intended lo mark the temperature of the 

 entering gas. i' is another thermometer similarly inserted into the 

 pipe where it leaves the drum, and t'^ is a third one, serving to note 

 the final temperature of the gas at its exit. The drum supports on 

 its top a broad shallow dish containing water to be evaporated. The 

 thermometer which marked the temperature of the room stood with- 

 in one foot of the upper end of the drum. The several thermome- 

 ters represented, were designed not only to show the temperature at 

 which the gas entered and left the apartment, but also the relative 

 portions abstracted by the main body of the drum, and by the pipe 

 respectively, and the extent of variation between the proportions 



