Steam and Hot Water for Greekhouse Heating. 181 



houses are warm enough, and no heat is needed from the pipes. 

 The general observations show that the times when temperatures 

 were lowest in the hot-water pipes were not warm mornings when 

 the fires were low, but cold ones when the steam-pipes showed 

 hig'h temperatures and all the heat was needed. In all points, 

 therefore, steam surpassed hot water. 



4. Coal consumption. — January twentieth, at 1 o'clock p. m., 

 both heaters were shaken down as usual leaving only a thin bed of 

 fire Id the box. All the coal used during the next two weeks was 

 weighed. Table IV^ shows the outdoor temperature and that of 

 the different houses, together with the averages during that time: 



