446 Retrospective Criticism. . 



vegetable suffering in those proud domes between December last and the 

 present month of July. In humbler tenements, beneath wood-framed roofs, 

 however, the inmates of the stove and green-house have passed the winter in 

 health." {Month. Chron., Aug. 1838, p. 146.) 



We shall be much obliged to any of our readers, if they will point out any 

 instances which may have come under their observation, in which glass has 

 been broken in " curvilinear roofs composed of iron frames." In the case of 

 all such roofs that we are acquainted with in the neighbourhood of London, 

 more glass has not been broken during the past winter than usual ; and this is 

 equivalent to saying that scarcely a single pane in fixed curvilinear roofs, such 

 as those in the Horticultural Society's Garden, has been broken. There is a 

 very large curvilinear iron-roofed house at Messrs. Loddiges's, in which not a 

 single pane has been broken during the last winter; and, indeed, we will 

 venture to assert that, by the frost alone, there has not been a single pane 

 broken in any curvilinear house whatever. Our firm belief is, notwithstanding 

 the assertions of Mr. Thompson of the Beulah Spa Nursery, (in an article 

 which was published the same month in several botanical periodicals, and 

 which was also offered to us, though we declined it,) that there never has been - 

 a single pane broken in any description of iron-roofed house, solely by the 

 contraction or expansion of the iron occasioned either by frost or sunshine. 

 There have been, of course, as in every other kind of plant-house, many panes 

 broken in iron houses, but never by simple contraction or expansion occa- 

 sioned by difference of temperature. The kind of iron house in which panes 

 are apt to be broken is, where the roof is formed into sashes, and where these 

 sashes are of some length, and arranged to slide, or move by some other 

 means, in order to give air. Whenever such sashes are above 5 or 6 feet in 

 length, and 2 or 3 feet in width, they are apt to twist when being moved ; and 

 this it is which breaks the panes ; while the cause, if it ha[)pens in summer, is 

 attributed to extreme heat, and, in winter, to extreme cold. Hence, in the 

 iron houses of the forcing department at Syon, and also at the Grange, a 

 number of panes have been broken every year : perhaps twice as many as in 

 the case of wooden houses similarly constructed. Had the roofs in such 

 houses been fixed, it is probable scarcely any panes would have been broken; 

 and, at all events, it is certain that not one would have been broken by the 

 contraction and expansion of the iron. We have here (at Bayswater) a glass 

 dome, l.'Sft. in diameter, which was put up, in the year 1824, for the protec- 

 tion of camellias, since which there has not been a single pane broken by any ,, 

 changes of weather whatever; and only one or two by the gardener, when prun- « 

 ing the vines which are trained under the roof. Finally, whatever objections 

 there may be to iron roofs, those who assert that they break the glass by mere 

 expansion or contraction cannot bring forward positive and definite proofs. 

 All that is stated in Mr. Thompson's article is mere assertion, depending for 

 its truth solely on his own authority. There is one curvilinear house open 

 every day in the year (except Sundays) to all persons ; we mean the con- 

 servatory at the Pantheorf. We shall be glad to know Vi'hat Mr. Thompson, 

 or any person who coincides with him in opinion, has to say to this house, 

 in which there has not been a single pane broken from change of temperature 

 during the whole of last winter. We are surprised that Dr. Lardner, who is 

 understood to superintend the scientific department of the Monthly Chronicle, 

 should not have made some enquiries into the subject, before he admitted 

 an article containing assertions so much at variance with truth ; and with the 

 known laws of the contraction and expansion of iron. 



With respect to the "ranges of glass, many thousand feet in extent," with 

 curvihnear roofs composed of iron frames, at Bretton Hall, there never was 

 any such range. There was formerly a superb domical conservatory, formed 

 wholly of iron framing; but it was sold and removed on the death of Mrs. 

 Beaumont, in the spring of 1832. See Vol. V. p. 681., where a view of this 

 conservatory is given ; and Vol. VIII. p. 361., where there is an account of 

 its sale. The magnificent conservatory now erecting at Chatsworth is neither 

 curvilinear, nor with an iron roof; and, besides, it is not yet glazed. 



