162 LECTURES. 



eating between the passage or staircase and individual rooms. Thesre, 

 when open or shut to the required degree, allow the air in the pas- 

 sages and staircase to be used as a milder climate, whether in the heat 

 of summer or the severity of winter — a perpetual ingress of fresh air 

 and discharge of vitiated air being constantly maintained in the hall, 

 passages, or staircase. 



Dr. Eeid then adverted to some models and to a series of diagrams, 

 with which he illustrated, practically, the various methods adopted in 

 experimenting on the subject, and in the construction of apartments 

 where ventilation was introduced under very diiferent circumstances, 

 from which we select the following examples : ^ 



1. In this case, the ventilating aperture was immediately below the 

 ceiling and above the window. A valve regulated the amount of 

 opening. The air entering or escaping by this aperture must pass 

 through a plate of perforated zinc about one foot deep, and extending 

 the whole breadth of the window. Area of aperture through the wall 

 nine inches square. 



2. A room having a ceiling universally porous, the air entering be- 

 tween it and an air-tight roof, and two apertures communicating with 

 this cavity and the external air which descends from one part of the 

 ceiling and escapes at another. 



3. A room where the fresh air is supplied from the whole surface 

 of the wall in which the chimney is placed, excluding those portions 

 below the level of the fire-place ; vitiated air escapes by a special flue 

 contiguous to the chimney. 



4. A room in which, when crowded, fresh air can be admitted freely 

 through a porous door from a prepared atmosphere in the passage, 

 vitiated air being permitted to escape by a large panel or window 

 above the same door. 



5. A house having a special ventilating shaft capable of acting on 

 all or any of the individual rooms, and of having its power increased, 

 when necessary, by the action of heat. 



6. A house in which all the vitiated air-flues are led into one large 

 ^fliie descending to the basement, passing then laterally into an ad- 

 joining shaft, whose altitude (from the basement to the roof) gives it 

 great additional power when the fire is kindled at the lower extrem- 

 ity- . , 



7. A house in which fresh air is supplied to the passage, stairs, and 



•principal apartments, from a special turret on the shaded side of the 

 house, while a discharging shaft, as in No. 6, commands the escape 

 of vitiated air. 



8. A house in which the heating apparatus (hot water) is so arranged 

 as to present a warm surface on the floor of the staircase and principal 

 .apartments. Similar arrangements can be made with steam appa- 

 ratus. 



9. A series of habitations supplied from a general source with a 

 -ventilating power, and a steam tube in every house, and in every 

 room of each house, where it is desired, in the same manner as houses 

 .are supplied at present with water and gas from one common source. 



10. A series of diagrams, showing the imperfections of ventilated 



