WARMING AND VENTILATING OCCUPIED BUILDINGS. 307 



TJDder these conditions, the total heating-surface might be reduced to 

 269 square feet for heating rooms of 35,316 cubic feet. 



A regular moderate and coustant temperature being much better 

 secured by a circulation of water that can be increased, checked, or even 

 Btopped, partially or entirely, as well as in the systems making use of 

 steam, we believe that it should generally have the preference, but 

 especially in the case of hospitals. 



27. Heating by the circulation of ivater of very high temperature. — In 

 regard to that system of heating by the circulation of water of high 

 temperature known under the name of Perkins's system, where the water 

 often attains a temperature above 572°, it cannot, without danger, be 

 carried through pii3es placed in the thickness of the floors or near pieces 

 of wood, which would be slowly affected by so high a temperature and 

 disposed to spontaneous combustion, as more than one fire has shown. 

 Also, at present, in establishments where this system of warming has 

 been adopted, all the pipes are in full view, and hung against the walls 

 or ceilings, which makes a very unpleasant appearance. It is, besides, 

 essential to surround with a grating or case those portions of these 

 pipes which are in contact with the building in order to prevent serious 

 accidents. On all these accounts we do not think it jjroper in a-ny case 

 to make use of this system of heating. 



28. Combination of hot-ioater and hot-air heating-apparatus. — The diffi- 

 culty of heating by means of a hot-air furnace to a greater distance 

 than 40 or 50 feet horizontally from the heaters may be overcome, as 

 we have said before, by placing iu the furnace, either a boiler or tubes, 

 called bottles, leading into the hot-water pipes communicating with the 

 radiators and the return-pipes. In this way a combined system of 

 heating is obtained, one part by warm-air and the other by warm water, 

 the latter being capable of useful effect at a great distance. 



29. Combination of tvarming and ventilation. — Apparatus for heating 

 by steam, hot water, and by both air- and water may easily be connected 

 with arrangements for direct ventilation ; water or steam vessels being 

 placed in the pipes or in the chimney to give it the proper activity. 



30. General conclusions from experiments on heating-apparatus made in 

 1865-'66. — Experiments, the results of which 1 have given in notes 

 appended to the Annals of the Conservatory, together with those which 

 I have already jjublished on fire-places, lead to the following classifica- 

 tion of the different forms of heating-apparatus examined, made with 

 reference to their heating-effect ; that is, the ratio of the heat which 

 they give out directly or indirectly in the places for which they are 

 intended to that developed by the fuel consumed. The table also 

 shows their advantages and defects as regards ventilation and effect on 

 health : 



