BENJAMIN THOMPSON, COUNT RUMFORD 33 



three times the width of the back, a rule which is followed to this 

 day. By making the angle of the sides of the fireplace 45, the 

 greatest possible amount of heat was reflected into the room. He 

 recommended the use of fire-clay instead of metal and of clay fire- 

 balls to insure complete combustion and increase the radiating 

 surface. Refuse coal-dust was made into briquettes. His chief 

 improvement consisted in the reduction of the size of the chimney 

 throat and in rounding off the edge of the chimney breast. Since 

 a room is warmed from the walls, and not by radiant heat passing 

 through the air, this work involved a study of the radiating power 

 of different surfaces and materials, and proceeding from the fact 

 smoke is pushed up, not drawn up the chimney, he was led to 

 make extensive investigations in the theory of ventilation. 



As it was hopeless to make the open fireplace an economical 

 heater, he turned his attention to the construction of cooking 

 ranges and to the utilization of waste heat of smoke and steam. 

 In the Bavarian House of Industry he passed the smoke from the 

 cooking ranges through copper pipes in a wooden cask, and used 

 it for cooking his pea-soup. From his experience he calculated 

 that the private kitchen expends ten times as much fuel as the 

 public kitchen. 



The progress of the century since then has been along the lines 

 indicated by Rumford. The range has been instituted for the 

 fireplace, closed and jacketed vessels are employed for cooking, 

 steam-pipes are used for heating buildings, and the utilization of 

 waste heat has become a factor of recognized importance in fac- 

 tory management. The first range built in this country in con- 

 formity with Rumford's principle was constructed under the di- 

 rection of Pyflfessnr John Kemp of Columbia College in 1708. 



The question of suitable covering for steam-pipes ~use3 for 

 heating rooms required for its solution a knowledge of radiation 

 from different surfaces, and in this field Rumford did some ex- 

 cellent original work. In these experiments he used two cylindri- 

 cal vessels of thin sheet brass filled with warm water and covered 

 with whatever coating or covering he wished to test. To deter- 

 mine which radiated heat the faster, he constructed a "thermo- 



