VENTILATION. 



297 



participate in the heat thus given off from 

 the pipes to the extent intended or sup- 

 Fig. 400. 



posed. This is accounted for by the 

 greater density of the air ; and from this 

 fact, also, it is likely to remain stationary, 

 because the means usually employed to 

 heat or cool the house cannot, from the 

 arrangement in most cases adopted, drive 

 it from its position. Nothing can be more 

 certain than that plants, in such buildings 

 where the heating and cooling powers are 

 so applied, must suffer considerably. Now, 

 the point we have arrived at is to change 

 the position of the cold air, constantly 

 and rapidly, either by the admission of 

 external air in hot weather, or by some 

 other contrivances, so as to mingle with 

 promptitute and certainty the cold and 

 hot air within the building. This can 

 certainly be accomplished, because of the 

 unequal gravity of the enclosed atmo- 

 sphere in different parts of the house, 

 provided means are introduced by which 

 one of the simplest laws of nature will 

 come into fall and active operation. 



" In the annexed woodcut (fig. 400) the 

 coldest part of the house is at a, and, of 

 course, the air is heaviest at that place. A 

 drain, therefore, communicating with b b, 

 will at once set the atmosphere in motion 

 in the direction indicated by the arrows, 

 provided an artificial temperature be kept 

 up by means of the heating apparatus. Dur- 

 ing summer, when artificial heat is unne- 

 cessary, I would open valves having com- 

 munications to them from these air-tunnels 

 at cc, to admit the external air, which would 

 invert the direction of the current, as is 

 now shown. An impulse would thus be 

 given, not only in winter, but in summer 

 also, by the colder air to the hotter, thus 

 keeping the atmosphere constantly excited 

 and in motion, besides equalising the tem- 

 perature throughout the entire building." 



The following remarks on ventilation, 



VOL. I. 



by Mr Errington, a very sensible writer 

 in "The Gardeners' Chronicle," and a 

 man of great practical information, are 

 so different from the usual practices and 

 opinions, that we gladly avail ourselves of 

 his communication in that excellent paper, 

 and have added a diagram, which we think 

 will elucidate his views. Mr Errington, 

 like ourselves, thinks that far too little 

 attention has been paid to ventilation, 

 and also that, in the way it is often prac- 

 tised, a very great waste of heat has been 

 occasioned. " There seems," he says, " to 

 have hitherto prevailed but one general 

 notion on the subject— viz., the throwing 

 open the back and front sashes the mo- 

 ment the sun shines ; and this happens to 

 be precisely the moment, in many cases, 

 when an accumulation of heat would be 

 beneficial, provided sudden scorchings 

 could be avoided. I must set out with 

 declaring my opinion, that before many 

 years have passed away, no mode of heat- 

 ing will be considered complete which 

 does not provide for a system of ventila- 

 tion, or rather purification, both day and 

 night. What I would, in the first place, 

 object to is the necessity that exists, in 

 the majority of cases, for permitting the 

 accumulated heat to escape at the highest 

 level at the back of hothouses. If nothing, 

 however, but the mere escape of heat was 

 involved in the question, I would forbear 

 to argue further ; but, with the heat, the 

 moisture also escapes, and this is not at all 

 times desirable." After protesting against 

 the doctrine held by some, that sufficient 

 fresh air gains admittance through the laps 

 of the glass, and arguing strongly for the 

 absolute necessity of purifying the air of 

 all glass houses, as well as making up for 

 the deterioration the air sustains by pass- 

 ing over many hundred feet of heated iron, 

 he proceeds to say, that, from observation, 

 he is persuaded "that it would be better, in 

 the great majority of cases, to make mois- 

 ture-loaded air traverse the whole interior 

 area of the houses, without permitting it 

 to escape at the back, allowing it to enter 

 at a low level, and departing by a high 

 one, both at front, by means of a copious 

 provision at the front of the house for 

 that purpose. To put a case : Suppose 

 a house, a lean-to," as in our fig. 401, 

 " 7 feet high at the front above the inte- 

 rior floor-level, and that floor-level 1 foot 

 above the ordinary ground line outside. 



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