Reinm-ks on Metallic Hot-houses. 



41 



you a few observations on the defects of curvilinear iron 

 roofs, which have occurred to myself in the management of a 

 house of this description, in the county of Dorset. 



This house was divided by a glass partition : both divisions 

 were paved with tiles, and, when I took charge of them, served 

 as green-houses, with vines trained on a treUis under the roof. 

 One of the divisions was afterwards converted into a pinery ; 

 but, however occupied, I always found it impossible to keep 

 the temperature of the houses to the required degree. The 

 circular roof concentrated the sun's rays so immoderately, 

 that the tops of the vines were actually scorched, even when 

 the doors and ventilators at the back were all open. This 

 was always the case in summer ; and in winter, it was with 

 the greatest difficulty, and only with the assistance of mats, 

 that we could keep out the frost ; the thermometer frequently 

 indicating only 40°, when strong fires were burning. 



I annex a section of the 

 house {fig. 84.) merely to show 

 the outline of its construction, 

 which I have found so de- 

 fective. In the first place, 

 the highly rarefied air under the 

 roof could not readily escape 

 by the ventilators behind ; and 

 the heat reflected from the 

 paved floor increasing this 

 unnecessary temperature, the 

 vines suffered : and in the next place, during winter, the 

 heat rising from the flues was dissipated upwards, and the 

 whole volume of the air within became cooled below the 

 necessary degree. 



It is true, this house may have been badly contrived, and 

 imperfectly finished; still, I am of opinion, that all houses 

 having iron roofs will be liable to the same objections, if 

 proper means be not taken to command the admission of air 

 in one season, and to keep up the proper degree of heat in 

 the other. I take the liberty of adding this remark, as a 

 warning to those who may, for the sake of neatness an(J 

 durability, resolve to have such houses erected. 



I am, Sir, yours, &c. 

 Atherstone Gardens, May 15. 1828. Geo. M'Leish. 



Vol. V. — No. 21. 



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