130 



HOTHOUSE-BUILDING. 



weather in winter between the upper 

 dome and the parts near the floor, 

 where the small and delicate plants w T ere 

 arranged, was usually 15° Fahr. ; and 

 in very severe weather, when much 

 artificial heat was required, the difference 

 became much greater. At such seasons 

 the glass round the base of the lower 

 dome has many times been thickly 

 coated with ice, when the higher parts 

 of the loftier trees were exposed to a 

 temperature of at least 90° or 100°, the 

 practical effects of which upon the plants 

 were ruinous." Such are the remarks of 

 one whose capability of judging we hold 

 in the highest estimation. The following 

 remarks by the same excellent authority 

 are in accordance with our own opinion : 

 " All stoves or glass structures for the 

 cultivation of flowering, and of course 

 fruit-bearing plants, ought to be so con- 

 structed as to admit of being protected 

 at night by a covering of some kind, 

 to prevent the waste of heat by radiation, 

 so that comparatively very little artificial 

 heat would be required at that season ; 

 and this is especially desirable with 

 respect to lofty houses containing plants 

 which require to be kept at a high tem- 

 perature. No cultivation can be con- 

 genial or successful in such cases, when 

 constant and incessant supplies of arti- 

 ficial heat require to be maintained to 

 meet the waste, whether occasioned by 

 radiation, or by imperfect fitting and 

 glazing. The effect of all this upon the 

 plants generally is to keep them con- 

 stantly under excitement, and for ever 

 green and growing. No mode which we 

 have yet seen proposed for the erection 

 of lofty stoves has presented any means 

 of meeting or preventing the evil to 

 which we refer. Such structures — that 

 is, lofty ones — are of course desirable ; 

 but they are entirely unfit for the perfect 

 culture of tropical plants — palms, and 

 indeed all the tall-growing kinds of endo- 

 genous plants, excepted." 



The ventilation of this house was 

 effected by horizontal ventilators placed 

 in the parapet wall, and also by upright 

 windows at the meeting of the lower 

 and upper domes, as well as by a skylight 

 which was raised by weights under the 

 terminating coronet at the top. 



Certainly the large house at Chats- 

 worth, the extensive range at Sion, and 



others of similar colossal dimensions, 

 have been most inefficiently ventilated 

 towards the top ; and from this some 

 of the evils alluded to have arisen. The 

 arrangements made in the new range of 

 lofty houses at Kew, although said to 

 be upon the newest and most complete 

 principles, and having all the errors of 

 previous erections as beacons for their 

 guidance, has been found nearly as defec- 

 tive as those that have gone before them. 



On the subject of inefficient ventila- 

 tion in metallic houses in general, we 

 here quote the opinion of Mr Niven, 

 who has had great experience in these 

 matters, and is withal a strenuous advo- 

 cate for such roofs. He says : " I con- 

 ceive, from most I have seen in the way 

 of metallic houses, that they have suffered 

 much in point of character from the 

 want of sufficient means of ventilation ; 

 bearing in mind the great increased 

 medium for the reception of the solar 

 rays by the curvilinear form of roof, as 

 well as its much increased surface of 

 light compared with the opaque roof of the 

 wooden house, with its heavy shadowing 

 rafters. Taking these circumstances into 

 consideration, I am only surprised that 

 the damage arising from defective means 

 of ventilation has not been greater 

 than what I have witnessed. This, how- 

 ever, is not the fault, it has been merely 

 the misfortune, of the metallic house. 



" The natural tendency of heated air 

 to ascend must always make the highest 

 parts of a lofty house much hotter than 

 the bottom, notwithstanding the heating 

 apparatus being placed under or near to 

 the floor level ; and without sufficient 

 outlet, the top must become so intolerably 

 heated as that no plant can possibly exist 

 in it. On the other hand, if too copious 

 ventilation is provided at the top, the 

 heated air will escape, causing an enor- 

 mous waste of fuel. That all supplies 

 of fresh air should be admitted at or 

 near to the floor is quite obvious, and 

 that it, by being so admitted, should 

 become moderately heated before reach- 

 ing the plants, is equally clear ; but to 

 regulate the whole atmosphere of a large 

 and lofty house, without an unnecessary 

 waste of fuel, is a desideratum much 

 wished to be attained. A well-appointed 

 circulation in all parts appears to us to 

 be the most effectual plan ; and, so far as 



