Forcing-House Miscellanies. 377 



temperature of the runs, foi the naked bulbs were let into the very 

 centers of the pipes. Two expansion tanks were provided one (A) 

 ten feet above the top of the heater, and another (B) twenty feet 

 above it. Either one or both of these could be shut oS by means 

 of a valve. The heater is designed for water and the pipes were 

 laid for water, being higher at the farther end. When the apparatus 

 was used for steam, the water was simply lowered in the heater 

 reservoir so as to make room for evaporation, and the piece of 4-inch 

 pipe which led out of the top of the heater served for a steam dome. 

 Of course the expansion tanks were shut off when steam was run- 

 ning. The advantages, therefore, were again in favor of the water 

 system, but all our former conclusions respecting the superiority of 

 steam over water, for the conditions given, were reaffirmed. 



The following tables give the detaled results of the various tests : 



