298 



VENTILATION. 



Supposing also that sliding ventilators 

 are placed in the front wall at the very- 



lowest point — say at the floor-level — 

 and that these ventilators lengthways 

 occupied nearly one-half of the frontage of 

 the house. So much for ingress — now for 

 the egress. Suppose, again, that the front 

 sashes (which meet the wall-plate where 

 the roof terminates in front) were made 

 to drop 6 inches— what, then, would be 

 the motion, or rather direction, of the air 

 through the body of the house 1 This I 

 have long since proved ; and, according to 

 my thinking, it throws some light on 

 ventilation matters. The cold air coming 

 in at the lowest level," as shown by the 

 direction of the arrows, " proceeds at once 

 along, or just over, the interior floor-line, 

 passes up the back wall, and returns down 

 the roof, passing out at the front aper- 

 tures at the top of the sashes ; and, as to 

 speed, in a corresponding ratio to the 

 discrepancy between the outer and inner 

 temperatures. Now, if this air be duly 

 charged with moisture and warmth on 

 entering the house, it is obvious that it 

 will deliver more of these two in thus re- 

 turning over the surface of the plants, 

 than it would if hurried out at the back 

 lights or ventilators. True, it will not 

 drive so keenly through, in one given 

 line ; it will, however, do more in the way 

 of purification : it will traverse in an equal 

 way the whole interior extreme outline, 

 causing all extraneous or stagnant air to 

 fall into a sort of whirlpool, from which it 

 cannot escape without purification. 



" If the principle of a special venti- 

 lation night and day be admitted, it only 

 follows that enough of interior heating 

 be furnished, in order to be enabled to 

 carry out such plans ; for, be it remem- 



bered, that although ventilation be de- 

 sirable, warmth is equally so. Some iron 

 piping should by all means be placed toler- 

 ably close to the lower front ventilators, 

 and the air should in most cases enter 

 below such piping. With such, and a 

 copious supply of moisture to temper the 

 air at its entrance, I am of opinion that a 

 slight amount of ventilation should be 

 kept up day and night, both winter and 

 summer, provided, as before observed, suf- 

 ficient warmth can be guaranteed through 

 a liberal amount of piping or otherwise." 



Mr Errington at the same time pur- 

 poses to retain back ventilators also, as 

 they may be used in extreme cases during 

 very hot weather. He merely contends that 

 such a mode of ventilation as has been 

 described above will be found more benefi- 

 cial than the back ventilators in ordinary 

 use, which he says " are robbers during 

 three parts of the year," and that his plan 

 will economise " both heat and moisture, 

 and keep the air constantly in motion." 



The coldest part of every hothouse is 

 close ^to the floor, and it is there also 

 that the greatest amount of foul and stag- 

 nated gases accumulate. To get rid of 

 the latter, and to change the former, led 

 us lately to adopt the following plan. The 

 stoke-hole behind the house experimented 

 upon is a close chamber 12 feet by 8, 

 and closely fitted with a door, which is 

 kept shut, unless when the fires are 

 examined with a view to regulate com- 

 bustion in the furnace. In this chamber 

 the heat is very considerable — often 20° 

 above that of the house within, taken 

 close to the floor. This heat, as will 

 readily be understood, proceeds from the 

 furnace front and ash-pit. An opening, 

 just over the boiler, a foot square, pro- 

 vided with one of Dr Arnott's valves, 

 was made ; the cold air from the floor of 

 the house rushed out, carrying with it, 

 no doubt, the noxious gases amalgamated 

 with it, and would escape into the atmo- 

 sphere every time the door was opened. 

 The deficiency of air within the house is 

 speedily made up by the ordinary means 

 employed for giving front air, as well as 

 through the laps of the glass, and all 

 other openings so favourable for the 

 admission of cold air, on account of its 

 pressure from without. 



For other methods of ventilation, vide 

 Vineries, Pits, &c. 



