156 FIXED STRUCTURES FOR GROWING 



improved on, and applied in the happiest manner, by Sir Joseph Paxton, 

 at Chatsworth ; and adopted by Mr. Marnock, in the Sheffield Botanic 

 Garden; Jedediah Strutt, Esq., at Belper ; William Harrison, Esq., 

 Cheshunt ; John Allcard, Esq., Stratford Green ; and at various other 

 places. The advantages of this description of roof are : 1. That the 

 roof does not require to be raised so high behind, in proportion to its 

 width, as in flat roofs ; because the descent of the water does not 

 depend on the general slope of the roof, but on the slope of the ridges 

 towards the furrows ; and the water in these furrows, being confined 

 to a narrow deep channel, and in a larger body than it ever can be on 

 the glass, passes along with proportionate rapidity. 2. That the 

 morning and afternoon sun, by passing through the glass at right 

 angles, produces more light and heat at these times of the day, when 

 they are, of course, more wanted than at mid-day. 3. The rays of 

 the sun striking on the house at an oblique angle at mid-day, the heat 

 produced in the house at that time is less intense than in houses of 

 the ordinary kind, in which it is often injurious, by rendering it 

 necessary to admit large quantities of the external air to lower the 

 temperature. 4. More light is admitted at all seasons, on the principle 

 that a bow window always admits more light to a room than a straight 

 window of the same width. 5. The panes of glass, if crown-glass be 

 employed, may be smaller than in houses the roofs of which are in 

 one plane, and yet, from there being a greater number of them, admit 

 an equal quantity of light ; from their smallness also, they will cost 

 less, and be less liable to be broken by the freezing of water between 

 the laps. 6. By the employment of sheet window-glass, which is 

 much thicker than crown-glass, panes of three or four feet in length 

 may be used, so that only one pane need be required for each division, 

 and consequently no lap being required, no breakage by frost can take 

 place, and no heated air can escape. And 7. That wind will have 

 much less influence in cooling the roof, because the sides of the ridges 

 -,. will be sheltered by their summits. Fj g> 129. 



Sir J. Paxton, to whom the merit of 

 this mode of roofing is entirely due, 

 has also adopted an improvement in 

 the construction of the sash-bar viz., 

 having grooves for the panes instead 

 of rebates (see figs. 128 and 129) ; 

 the advantages of which grooves are, 

 that less putty is required, and that 

 what is used does not so readily 

 Section of an iron separate from the wood, and thus 

 bar with admit the wet between the wood and 

 grooves for trie > ,,,-. . , 



ala** the putty. The roofs of such houses 



are en/rely fixed, and ventilation 

 effected either by having the perpendicular ends of grooves for the 

 the ridges moveable on hinges, or by the front glass glass. 

 and ventilators in the back wall. The expense of this mode of roofing 

 is doubtless greater than that of the common flat mode, but not so much 



