Qiieries and Ansniaers to Queries. 185 



Construction of Hot-homes. — Sir, As the best mode of constructing and 

 heating glass houses is a matter of the first importance in exotic cultivation, 

 I shall be much obliged by your answering the following enquiries ; — 



In one of your late Numbers you observe that you approve of metallic 

 houses, as admitting more light, but that Mr. Atkinson, and the managers 

 of the Horticultural Society establishment, are of a different opinion. Will 

 you have the goodness to inform us what their objections are, and how far 

 you consider them to be well founded. Iron houses are said to be subject 

 to great and sudden variations of temperature, owing to the rapidity with 

 which the materials transmit heat, either internally, or externally, accord- 

 ing to circumstances, so that while the sun's rays produce a scorching effect 

 in summer, a great addition of fuel is required to keep up the temperature 

 in winter. All the gardeners in my neighbourhood are decidedly against 

 them ; but a manufacturer of these houses, with whom I was conversing 

 on the subject, asserted that the metallic surface exposed was too small to 

 be likely to produce much effect, but that, if the fact were as stated, (which, 

 however, he was not prepared to admit,) it must be attributed rather to the 

 diminished quantity of opaque surface. 



From the interesting article in your last Number, on heating houses, &c., 

 by means of water, there can, I think, be little doubt of the superiority of that 

 mode to all others; but, as the temperature of the water must be consider- 

 ably lower than that'of steam, I wish to know whether an increased quan- 

 tity of pipe or reservoirs will not be necessary to heat the same space, and 

 if so, in what proportion. Your opinion on these points will, I dare say, 

 interest many of your readers as well as — -A Lover of Improvement. March. 



Our correspondent having stated both sides of the question, little more 

 is left for us to do than to state that we decidedly prefer iron, notwith- 

 standing all the objections that have been urged against it. These objec- 

 tions are founded on truth ; but, for the very reason which has given rise 

 to the main objection, namely, the excess of heat which is produced by 

 the admission of so much light, we prefer the iron. 



It is affirmed by some that iron hot-houses are not more durable than 

 wooden ones, while they are much more expensive, both at first erection, 

 and to keep warmed. Admitting that this were the case, we should still de- 

 cidedly prefer a construction of iron, because money will overcome the 

 other objections, but no human power can increase the light in a hot-house, 

 otherwise than by increasing the transparency of the roof. Whoever can 

 get access to the ii'on hot-houses at Syon (Vol. II. p. 107.), will have 

 their doubts settled as to plants thriving in them. With respect to the 

 proportion of pipe or reservoir necessary to heat any given volume of air, 

 &c., we believe nothing has hitherto been determined on the subject. Mr. 

 Tredgold, we understand, is now engaged in some calculations, having 

 that and other objects in view, and he, of all the other engineers that we 

 know of, is the most competent for such an undertaking, and for directing 

 the construction of this department of gardening architecture. — Cond. 



Black Italian Poplar. — Sir, I was surprised to see a remark from one 

 of your correspondents (Vol. III. p. 410.), that the black Italian poplar, 

 though of quicker growth than the Lombardy, is inferior in respect 

 to timber. That the latter will hardly find a purchaser at any price, I 

 know by experience. Of the black Italian I have no such experience, but 

 have always understood the timber to be nearly, if not quite the best of the 

 whole tribe. More than one of your correspondents will be glad to have 

 this point settled by reference to some sufficient proof. I once had occa- 

 sion to observe a curious circumstance in respect to the propagation of the 

 black Italian poplar, to which I never recollect hearing of a parallel. I 

 asked a neighbour for some cuttings of it, which he directed his gardener 

 to prepare after the manner of the nurserymen ; viz. by cutting shoots about 

 the thickness of a thumb into lengths of about 2 ft. These I planted, ais 



