306 WARMING AND 'VENTILATING OCCUPIED BUILDINGS 



Heating-apparatus of tbis kind in use at Guy's Hospital, Loudon, at 

 the Sydenham Palace, and all those used in warming green-houses, prove 

 that, provided the pipes be sufficiently large, a small difference in height 

 between the ascending and descending pipes is sufficient to maintain the 

 circulation with even a slight difference of temperature. Another con- 

 clusive example is found in the apparatus used in warming some baths. 



The hot-water circulating-i)ipes may be arranged to warm the air 

 either in the lower i)Ortions or in vertical shafts built in or against the 

 walls, through which the outside air passes and becomes warmed by 

 contact with the pipes. 



The iirst arrangement, in which the pipes may be in sight throughout 

 their whole length and placed in easily accessible places, renders leaks 

 of little consequence, and allows them to be easily found and stopped. 



The second, which is used by d'Hamelincourt, and in which hand-hole 

 plates are placed at the top of each section, gives almost the same 

 facility and allows of the removal of the leakage- water. 



Both these plans are more cheaply applied than that which has been 

 adopted by L. Duvoir-Leblanc, who carries the water in the thickness 

 of the floors, and they are free from the somewhat too severe condem- 

 nation which has been visited upon the plans of that builder. 



In these systems, radiators may be entirely dispensed with or confined 

 to one in each ward for the comfort of the patients. 



26. Proper proportions of heating-surf aces. — A hot-water heating-appa- 

 ratus does not give out as much heat as a steam-heating apparatus with 

 the same surface. An examination of the results obtained at Lariboi- 

 siere Hospital shows that a heating-surface of 291 square feet for rooms 

 with a capacity of 35,316 cubic feet is scarcely sufficient in very cold 

 weather, and we think that it would be better to give to the radiators 

 or receivers placed within the rooms to be warmed at least 323 to 344 

 square feet of total heating-surface for that capacity of 35,316 cubic feet 

 in places similar to hospitals. 



In regard to apparatus placed in cellars and designed to warm air 

 which is carried thence through pipes which may cool it, or into rooms 

 not kept constantly warmed, prudence requires that the heating-surface 

 should be 538 square feet for warming rooms containing 35,316 cubic 

 feet, and it is also necessary that the air should not be carried to a great 

 distance. 



lu general, this system has a smaller heating-capacity than that in 

 which the water is carried in pipes or through the air-passages. 



But when the heater, the pipes, and the radiators are all contained in 

 the room to be warmed, the loss from waste heat is reduced, as in the 

 €ase of stoves, to that carried off" by the chimney. Besides, since the 

 heat requires to be kept moderate, this system unites the advantage of 

 healthfulness to that of economy of fuel, and appears to me as a system 

 of general heating preferable to the other systems employed for the same 

 purpose. 



