172 EEPORT OF THE ARCHITECTS. 



To ascertain the demands to be made upon the apparatus for heating, 

 the conditions of the building were studied, in order to arrive at the loss 

 of heat inside the building for an external temperature of zero and an 

 internal temperature of 70° Fahrenheit. This loss of heat is caused by 

 the exposed surfaces of the building, which consist of hollow brick walls 

 plastered inside, of tin roofs lined with felt and supported by noii-con- 

 ductiug fire-proof material plastered inside, and of windows having two 

 thicknesses of glass with inclosed air-space. It is increased by an 

 amount due to leakages, absorption of heat by the soil, transfusion of air 

 by the opening of doors, &c. To allow for contingencies, the required 

 heating surfaces resulting from above causes were increased by about 

 fifteen i^er cent, and the generating power of steam three times. 



The necessity for such a disproportionate amount of generating power 

 Is explained hj the fact that the condensation is enormous when the 

 steam circulating j)ipes and radiators are first heated up, because their 

 specific heat is very high when compared with that of the air. When the 

 circulation is once established, the demand upon the boilers decreases 

 to an amount equal to the heat radiated and carried off by the air from 

 the heating surfaces, provided that the main circulating (or flow) pipes, 

 which are not to act as radiators, but rather as vehicles to carry the 

 heat to the most extreme points of the building, are protected by a sufiS- 

 cient coating of non-conducting material, which should be provided for, 

 the sooner the better. 



It is evident that for such nice adjustments there were no funds 

 available so far. 



Continued satisfactory heating by the direct radiating system de- 

 mands, with such an extensive apparatus, constant and close attention ; 

 otherwise there will be a great waste of fuel in mild weather, and well- 

 founded complaint of overheating. 



As the building is heated up, radiators must be shut off until no more 

 heating surface is left than is required to balance the loss of heat, which 

 in this climate is very variable. The offices require more heat, rela- 

 tively, than the halls ; and if, after the building is warm throughout, 

 steam were shut down entirely to prevent overheating the halls, as 

 would happen in mild weather, the offices could not be occupied for 

 want of heat long before the first sensation of coolness appeared in the 

 halls. The cause of this is tliat the ratio of cooling surface to space (or 

 cubic contents) "is much greater in the case of the small rooms than in 

 the halls, which form a huge reservoir of heat, contained in the inside 

 walls and objects as well as in the air. 



It is necessary to put the whole force on once a day in order to get 

 circulation of steam throughout. In mild weather shut down as soon 

 as overheating begins. In extremely cold weather the full force is to 

 be kept up continuously. 



It being established by experiment that about 25 per cent, of the entire 

 heat absorbed in evaporating the water in the boilers will be restored by 



