GENERAL PRINCIPLES. 



109 



spherical figure or globe ; but as this 

 figure seemed to be unattainable in 

 practice, he then proposed to make the 

 roof the segment of a circle. This may- 

 be said to have been the most scientific 

 improvement suggested up to that period; 

 and out of it arose the various modifica- 

 tions known as curvilinear roofs, of which 

 many exemplifications are to be met 

 with, but certainly not so many as might 

 have been expected. Long before this, 

 however, we should have observed, span- 

 roofed houses were in use. These possess 

 many of the properties of the curvilinear 

 form, without being so expensive in the 

 erection. We were long opposed to 

 curvilinear houses on account of the 

 expense, more especially those of the 

 lean-to form, or those which, although 

 the roof was curved, still retained the 

 opaque back wall, a mode of construction 

 which to us appeared to be only a very 

 slight improvement indeed over those 

 in common use with straight roofs, and 

 one certainly not proportionate to the 

 extra expense of their formation. 



The improvements in hothouse-building 

 may be said to be now only " beginning 

 to begin ;" and there is, no doubt, a wide 

 field open for the exercise of judgment 

 and invention. 



A writer in the "Annals of Horticulture" 

 observes : " There is yet much remains 

 to be realised in the erection of houses 

 for the cultivation of plants, not only as 

 regards their number and dimensions, 

 but also their arrangement and details. 

 We seldom see more than the same kind 

 of flat lean-to or span roofs — the same 

 kind of formal stages where the plants 

 are grown in pots — and the same kind of 

 formal beds when the latter are planted 

 out in borders of prepared soil. Even 

 refinements or elegances of construction 

 fail to invest such buildings with any 

 character of distinctness or novelty, 

 owing to the sameness or monotony 

 which forms the basis of the design." 



The last and greatest improvement 

 in hothouse roofs is certainly that of the 

 ridge-and-furrow form, first suggested by 

 the late Mr Loudon about the year 1816, 

 and afterwards so completely wrought 

 out by Sir Joseph Paxton in the large 

 house at Chatsworth, and elsewhere, and 

 more recently by covering in nearly 

 20 acres for the Great Exhibition in 



Hyde Park, the most stupendous erection 

 hitherto constructed of iron, timber, and 

 glass, and exemplifying most clearly the 

 possibility of extending the same kind of 

 pillared covering over any space, however 

 large. 



A third claimant has, we may observe, 

 very recently, in " The Builder " and 

 other papers, come forward, not only to 

 share with Mr Loudon and Sir Joseph 

 Paxton the merit of this discovery, but 

 in reality to claim the whole merit to 

 himself. We are not so much surprised 

 at the claim made by the reverend gen- 

 tleman, as at his extreme modesty in not 

 asserting this supposed right long ago — 

 the more so, as he has been a frequent 

 correspondent in several horticultural 

 periodicals during a considerable number 

 of years. From our own personal inti- 

 macy with the late Mr Loudon, we know 

 that the ridge-and-furrow principle of 

 roofing was thought of by him long- 

 before any exemplification of it had been 

 attempted in Britain. To Sir Joseph 

 Paxton, however, the merit belongs of 

 bringing this greatest of all improve- 

 ments into practical use ; and even had 

 the idea been entertained by others, it is 

 questionable if many would have had 

 the boldness or the means to have brought 

 it to perfection. 



Mr Loudon's first idea of this mode of 

 roofing suggested itself to him after 

 reading a paper by Sir George M'Kenzie, 

 published in 1815 in the " Transactions 

 of the Horticultural Society of London," 

 " on the form which the glass of a forcing- 

 house ought to have, in order to receive 

 the greatest possible quantity of rays 

 from the sun." 



The Rev. Mr Carlisle, the claimant 

 to whom we have alluded above, has 

 lately stated, in a letter to the editor of 

 the " Morning Herald, " that, so early 

 as 1828, when he began to make his 

 gardening experiments, he " spent con- 

 siderable time on the laws of optics and 

 the formation of a glass roof embracing 

 three aspects, in order to prolong the 

 heat, and obviate the necessity of late 

 fire-forcing." He calls his invention the 

 Vandyke roof. " In the midst," he says, 

 " of hail-storms rushing like eddies from 

 all points of the compass, I tried at 

 various times the comparative merits 

 of the common flat roof and the Vandyke 



