9 



HOT HOUSE ARCHITECTURE. 



All horticultural erections should be of wood, in preference to metalic 

 matter, not only because of its greater economy and fitness for the pur- 

 pose, but also on account of durability and elegance of effect. We are 

 perfectly aware that this has been a controverted point, but we have been 

 so situated as to be enabled to judge of the relative merits of both without 

 prejudice or interest, and our conclusion, after the experience of 

 thirty years, is in unison with those of the majority of intelligent gar- 

 deners, who alone are capable of judging, as their conclusions are drawn 

 from actual practical experience. It would be out of place here to enter 

 into the merits or defects of either ; but we think it necessary so far to 

 explain our opinions on this subject, that our views may be the less hable 

 to misconception in the remarks on the plant structures we think necessary 

 for the production of fine flowering exotics. 



We are also supported in these views by Mr. Thomson, of the Sion 

 nursery, Norwood, whose experience in those matters justify us in quoting 

 his authority. " Having had fifteen years of practical experience in 

 managing upwards of three thousand running feet of glass," he says, in a 

 communication prepared by him for this work, " I am enabled to speak 

 with some decision on the subject, and I feel fully justified, indeed, in 

 saying, that when the respective merits of wood and iron are fully ascer- 

 tained, the prejudice in favour of the latter will cease to exist in the minds 

 of those practically acquainted with the properties of the two materials. 

 The expansive power of metaUc substances is Yery great, and so powerful 

 have I known the action of the sun^s rays in expanding the iron rafters 

 of a large roof on a hot summer's day, that the strength of two, and 

 sometimes three men has been insufficient to force do^\Ti the sliding 

 lights for the admission of air. In fully equal proportions have I wit- 

 nessed the contraction of the metal during the intensit}^ of winter, 

 leaving large apertures between the rafters and the lights, and admitting 

 the external air sufficiently to counteract the power of two strong flues. 

 This occurrence took place in February, 1830, and the house in question 

 was of moderate dimensions, when compared to the wood-roofed ^inery 

 I am about to contrast it with. The building was forty feet long, by sixteen 

 wide, and nine feet high, having a pit in the middle for the culture of 

 pines, which very much reduced the quantity of air to be rarified. The 

 wood-roofed vinery was fifty feet long, by fourteen feet wide, and foiuteen 



