114 



HOTHOUSE-BUILDING. 



spaces from the sides to the first or even 

 second lines of columns may be separated 

 from the rest by a glass screen, constructed 

 in a similar way to the sides of the build- 

 ing, fitting the partitions to either side 

 of the columns, so as to clear the trussing- 

 rods, and to the edge of the valley above- 

 while their lower edges may run on iron 

 rails fixed to permanent stone or iron 

 sills, or portable wooden ones. 



It will be observed that the principle 

 of roofing here illustrated is not very dif- 

 ferent from that adopted at railway ter- 

 mini. It is to these that the idea is due. 

 Such roofs have not as yet been employed 

 in hothouse-building ; but that, variously 

 modified, they are adapted for the pur- 

 pose of roofing in large areas, none will 

 dispute. The upright supports, as well 

 as the suspension-rods, can all be turned 

 to good account, as they present us at 

 once with the means of cultivating, to the 

 very highest degree of perfection, plants 

 of scandent habits, amongst which are 

 many of our most gorgeous flowers. The 

 columns of support not only afford us a 

 ready means of getting rid of the rain 

 which falls on the roof, but a proportion 

 of them may be made radiators of heat, 

 by causing hot water to circulate through 

 them. 



The glass we proposed to use was 21 

 ounces to the foot, and in sizes 1 foot by 3. 



Winter ventilation was to be effected 

 chiefly by bringing in a supply of air 

 through 9-inch fire-clay tubular pipes, 

 their outer orifices being in the parapet 

 wall all round at 10 feet apart, and their 

 inner openings dispersed over the floor of 

 the house. 



A house of this altitude is well adapted 

 for the cultivation of fruit-bearing trees 

 and flowering plants of considerable size ; 

 but it will at the same time occur to the 

 experienced eye of the practical cultivator 

 that the roof is, especially towards the 

 ridges, too high for the successful culti- 

 vation of plants of very dwarf habits — 

 that is, the plants close to the ground 

 would be too far from the light. These 

 could, however, be accommodated, by 

 placing them on suspended shelves near 

 to the glass. Another advantage such a 

 structure would afford, during winter, 

 would be the conservation of crops al- 

 ready grown, such as lettuce, endive, cau- 

 liflower, early varieties of brocoli, cardoons, 



celery, &c, which could be taken from 

 the open ground in autumn and trans- 

 planted into the coldest parts of the 

 house — cardoons, celery, cauliflower, and 

 brocoli, &c, being laid in, as the technical 

 phrase is, by the heels. Only those who 

 have a large winter supply to provide for, 

 can fully appreciate such an accommoda- 

 tion. Gardens covered with glass are one 

 of those additions to modern luxury which 

 may be looked forward to. 



Nor is it at all improbable that suspen- 

 sion-roofs may yet be adopted for covering 

 large conservatories, the fulcra for the 

 suspended chains being placed at the four 

 corners — vide " Mechanics' Magazine, " 

 vol. xxxiii. p. 500, where the principle of 

 Dredge's suspension-bridges is noticed. 

 A better method still would be to extend 

 the tubular iron columns which support 

 the ends of the metallic gutters to a 

 sufficient height above the valleys, and 

 employ them as the fulcra for suspending 

 the roof from without, instead of by 

 perpendicular columns and tension-rods 

 from within, as has hitherto been done 

 in roofs of extraordinary size. 



Another advantage which this form 

 (the ridge-and-furrow one) possesses is, 

 that the rays of the sun are presented 

 more perpendicularly to the glass in the 

 morning and afternoon, when they are 

 weakest, and more obliquely at noon, 

 when they are strongest. 



In the course of a lecture lately 

 delivered by Sir Joseph Paxton before 

 the Society of Arts in London, he ex- 

 plains the principles of this improved 

 roof as follows : " In the construction 

 of glass houses requiring much light, 

 there always appeared to me to be one 

 important objection. In the plain lean-to 

 or shed roofs, the morning and evening 

 sun — which is, on many accounts, of the 

 greatest importance to forcing fruits — ■ 

 presented its direct rays at a low angle, 

 and consequently very obliquely, to the 

 glass. As at those periods most of the 

 rays of light and heat were obstructed 

 by the position of the glass and the 

 heavy rafters, so that a considerable 

 portion of time was lost both evening 

 and morning, it consequently became 

 evident that a system by which the glass 

 would be more at right angles to the 

 morning and evening rays of the sun 

 would obviate the difficulty, and remove 



