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VENTILATION. 269
published in several scientific and technological journals. It is there said that the ob-servations of Saussure, and other scientific travellers in mountainous regions, demon-strate how difficult and painful it is to make muscular or mental exertions in rarefied air.Even the slight rarefaction of the atmosphere, corresponding to a low state of the bar-ometer, at the level of the sea, is sufficient to occasion languor, lassitude, and uneasi-ness, in persons of delicate nerves; while the opposite condition of increased pressureas indicated by a high state of the barometer, has a bracing effect upon both body andmind. Thus, we see how ventilation, by the powerful draught of a high chimney-stalk,as it operates by pumping out, exhausting and attenuating the air, may prove detrimen-tal to vivacity and health ; and how ventilation, by forcing in air with a fan or a pump,is greatly to be preferred, not only for the reason above assigned, but.because it pre-vents all regurgitation of foul air down the chimneys, an accident sure to happen in theformer method. Genial air thrown in by a fan, in the basement story of a building,also prevents the stagnation of vapors from damp and miasmata, which lurk about thefoundation of buildings and in sewers, and which are sucked in by the rarefying plan.Many a lordly mansion is rendered hardly tenantable from such a cause, during certainvicissitudes of wind and weather.
The condensing plan, as executed by the engineers, Messrs. Easton and Amos, at theReform Club House, consists of a large fan, revolving rapidly in a cylindrical case, andis capable of throwing 11,000 cubic feet of air per minute, into a spacious subterraneantunnel, under the basement story. The fan is driven by an elegant steam-engine, workedon the expansion principle, of 5 horses’ power. It is placed in a vault, under the flag-pavement, in front of the building; and as it moves very smoothly, and burns merelycinders from the house fires, along with some anthracite, it occasions no nuisance ofany kind. The steam of condensation of the engine supplies 3 cast-iron chests withthe requisite heat for warming the whole of the building. Each of these chests is acube of 3 feet externally, and is distributed internally into 7 parallel cast-iron cases,each about 3 inches wide, which are separated by parallel alternate spaces, of the samewidth, for the passage of the air transversely, as it is impelled by the fan.
Fig. 174 is a transverse vertical section of the steam-chest, for heating the air; fig. 175is a plan of the same; and fig. 176 is a perspective view, showing the outside casing,also the pipe a, for admitting the steam, and the stop-coek b, for allowing the condensedwater to escape.
175 176
,This arrangement is most judicious, economizing fuel to the utmost degree; becausethe steam of condensation which, in a Watt’s engine, would he absorbed and carried offby the air-pump, is here turned to good account, in warming the air of ventilation du-ring the winter months. Two hundred weight of fuel suffice, for working this steam-engine during twelve hours. It pumps water for household purposes, raises the coalsto the several apartments on the upper floors, and drives the fan ventilator. The air,in flowing rapidly through the series of cells, placed alternately between the steam-cases, can not be scorched, as it is generally with air stoves; but it is heated only to thegenial temperature of from 75° to 85° Fahr., and it thence enters a common chamber ofbrickwork in the basement story, from which it is let off into a series of distinct flues,governed’ by dialled valves or registers, whereby it is conducted in regulated quantitiesto the several apartments of the building. I am of opinion that it would not be easy todevise a better plan for the purpose of warming and ventilating a large house ; and Iam only sorry to observe, that the plan projected by the engineers has been injudiciouslycounteracted in two particulars.
The first of these is, that the external air, which supplies the fan, is made to traversea great heap of coke before it can enter that apparatus, whereby it suffers such frictionas materially to obstruct the ventilation of the house. The following experiments, whichI made recently upon this point, will place the evil in a proper light: Having fittedup Dr. Wollaston’s differential barometer, as an anemometer, with oil, of specific gravity0-900 in one leg of its syphon, and water of 1-000 in the other, covered with the said oilin the two cisterns at top, I found that the stream of air produced by the fan, in a cer-