1396 



GREENHOUSE 



GREENHOUSE 



Belvoir Castle, and over which grapes were growing, 

 received the additional protection of glass sash set in 

 front of the inclined walls and over the vines. In addi- 

 tion to this, flues were constructed behind the wail in 

 which heat might be supplied. The construction of 

 hollow heated walls was not uncommon in that day. 

 The satisfactory results that followed this experiment 

 induced Switzer to design glass-covered walls. The 

 "glasshouse" which he pictured in the "Practical 



1750. Switzer's glasshouse, built on an inclined wall (1731). 



feet wide in the clear (Fig. 1750). At the back of this 

 house is an inclined heated wall on which the grapes 

 are grown. Three and one-half feet in front of this a 

 framework is erected to receive the sash. There are 

 three tiers of openings or windows along the front, the 

 two lower ones of which are for window-sash, and the 

 upper one is vacant in order to provide for ventilation 

 and to allow space to receive the lower sash when they 

 are hfted up. The whole structure is covered with a 

 roof or coping. Switzer declares that the introduction 

 of these covered sloping walls "led the world" to the 

 "improvement of glassing and forcing grapes, which 

 was never done to that Perfection in any Place as it is 

 upon some of the great Slopes of that elevated and 

 noble Situation of Belvoir Castle." Johnson, in his 

 "History of EngUsh Gardening," quotes the remarks of 

 Switzer, and makes the statement that the use of these 

 walls "led to the first erection of a regular forcing struc- 

 ture of which we have an account. ' ' The immediate out- 

 come of these covered walls seems to have been the 

 lean-to greenhouse, and from that structure has per- 

 haps developed the double-span glass range of the pres- 

 ent day. Long before Switzer's time plants were forced 

 in a crude way, even by the Romans, mostly by being 

 placed in baskets or other movable receptacles, so that 

 they could be placed under 

 cover in inclement weather; 

 but the improvements of 

 Facio and Switzer seem to 

 have been among the earliest 

 attempts in England to make 

 low glass ranges for plants. 



It was about the begin- 

 ning of the nineteenth century 

 that great improvements be- 

 gan to be made in the glass- 

 house. This new interest 

 was due to the introduction 



of new plants from strange countries, the improvement 

 of heating apparatus, and the general advance in the 

 art of building. The ideals that prevailed at the open- 

 ing of the century may be gleaned from J. Loudon's 

 "Treatise on Several Improvements Recently Made in 

 Hot-Houses," London, 1805. One of the devices recom- 

 mended by Loudon will interest the reader. It is shown 

 in Fig. 1751. The bellows is used for the purpose of 

 forcing air into the house, that the plants may be sup- 

 plied with a 

 fresh or non- 

 vitiated at- 

 mosphere. "By 

 forcing the air 

 into the house, 

 once a day or 

 so, double the 

 quantity of air 

 which the 

 house usually 

 contains" can 

 be secured. The 

 house could be 

 "ch arged.' ' 

 The tube lead- 

 ing from the 

 Curtains run 



1751. Loudon's device for charging a greenhouse with air. 



bellows is shown at b; it discharges at c. 

 on wire, i; the curtain cord is at /. 



Greenhouses are now built on the plan of the long 

 low glass range with sides varying from 5 feet 6 inches 

 to 7 feet in height. The tendency in commercial 

 structures is for a height of 7 feet from ground to eaves. 

 The taller glass structures are used for conservatory 

 purposes, housing such table plants as palms, tree- 

 ferns, or the hke, or when an architectural feature is 

 desired. The general tendency of the building of glass 

 structures is toward extreme simplicity (Fig. 1547, p. 

 1256). In the extreme South, lattice-work buildings are 

 sometimes used for the protection of plants, both from 

 light frosts and from the sun (Fig. 1752). The heating 

 now emjjloyed in this country is of three different kinds : 

 hot water under very low pressure or in the open-tank 

 system; hot water in practically closed circuits; and 

 steam. Hot water under low pressure is an old-time 

 mode of heating, and is not now popular in this coun- 

 try except for conservatories and private establish- 

 ments. The heavy cumbersome pipes are not adapted 

 to laying over long distances and under varying con- 

 ditions. The commercial houses are now heated by 

 means of wrought-iron pipes, which go together with 

 threads. The comparative merits of steam and hot 

 water in these wrought-iron pipes are much discussed. 

 For large estabhshments, hot water under pressure is 

 now employed to some extent. Much progress has 

 been made in methods of heating in recent years, and 

 either steam or hot water gives good results when com- 

 petently installed. The merits of one system or the 

 other are very largely those of the individual estab- 

 hshment and apparatus, and the personal choice of 

 the operator (see page 1403; also pages 1400 and 

 1402). 



The simple straight and direct house is now much 

 in favor with the commercial growers of carnations, 

 chrysanthemums, violets, roses, vegetables, and with 

 propagators. Most of the greenhouse construction 

 firms are designing houses most admirably adapted to 

 the growing of these plants. Each firm has a few 

 original forms worked into the detail plans, calculated 

 to appeal to the growers' fancy. Perhaps the ideal 

 structure for carnations, for example, is a single 

 detached house, about 50 feet wide and 500 feet or less 

 in length, with ventilators on each side of the ridge 

 and on each side below the eaves, and the eaves, or the 

 gutters, 6 feet above the grade. 



With the refinements of architecture and the growth 

 of satisfaction in home-building, the glasshouse is 



