. Preventive medicine and hygiene. l perforations, the widenedend of the conical opening debouching on the interior of the wall. Theholes through the bricks are about 2/10 inch in diameter externallyand 11/4 inches internally. Tobins tube consists of a large upright tube, about 5 or 6 feethigh, which conducts outside air into the room through the wall. The Sheringham valve is a small vertical flap door in the wall nearthe ceiling, balanced by a counterpoise, and hinged so as to fall forward VENTILATION 761 toward the room; it is cased hi at the sides and front, so that thecurrent can only pass
. Preventive medicine and hygiene. l perforations, the widenedend of the conical opening debouching on the interior of the wall. Theholes through the bricks are about 2/10 inch in diameter externallyand 11/4 inches internally. Tobins tube consists of a large upright tube, about 5 or 6 feethigh, which conducts outside air into the room through the wall. The Sheringham valve is a small vertical flap door in the wall nearthe ceiling, balanced by a counterpoise, and hinged so as to fall forward VENTILATION 761 toward the room; it is cased hi at the sides and front, so that thecurrent can only pass upward. Stevens drawer ventilator is like a drawer lacking its back. It ismade to fit into a hole in the wall in such a way that when the draweris shut the hole is airtight, and wlicn tlie drawer is open air can enter. Hinckes-Bird ventilator is nuide of the opening l^etween two ordi-nary window sashes when the lower is raised, and the lower openingclosed by means of a specially high sill or by au accurately fitting blockof Fig. 94.—Diagrammatic Sketch of Various Provisions for Ventilation.—A, Sashwindow with Hinckes-Birds arrangement. B, Hopper sash-light falUng inwards. C,Louvred outlets. D. McKinnells ventilator. E, Sheringhams valve. F, Tobinstube (showing valve open). G. Ellisons conical bricks. H and I, Grid ventilatorsbelow floor joists. (From Hygiene and Public Health, by Drs. L. C. Parkes andH. R. Kenwood, London, H. K. Lewis, Philadelphia, Blakiston, 1911.) These various devices should be protected with valves so that theymay be regulated. Sometimes it is advisable to provide gauze or cot-ton filters to keep out the dust. Natural ventilation is greatly aided by means of warming the airin the outlet duct. The best example of this is the open fireplace, orother devices for warming the air in outlet tubes already referred to. A¥herever possible, open windoAvs are the best and simplest meansof ventilating a room. Any system of mechanical ventilation at bestis
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Keywords: ., bookauthorwh, bookcentury1900, bookdecade1910, booksubjecthygiene
