BOOK III. HOT-HOUSE FURNACES AND FLUES. 323 



1643. Holes for vine-stems (Jig. 2G8./,/). In all parapets or front arrangements 

 where vines are to be introduced from without, particular care must be had to provide for 

 the withdrawing of the vines, even when their wood is of a considerable age and thick- 

 ness. For this reason, where horizontal shutters are used, the lower styles or pieces 

 against which they shut, should always be moveable ; and, in general, it may be stated, 

 that of the various modes for the introduction of the vine from without which have been 

 adopted, that by cutting off a corner of the sloping or front sash, is the best ; by this 

 means, when the sash is opened, a vine of almost any size (Jig. 269. a) may be taken out 

 with ease. A piece of thin board or cork cut every year to fit the increasing diameter of 

 the shoot is screwed to the wall-plate or lower style, as the case may be, and the vacuity, 

 which must necessarily be left around the stem, is closed up with moss. When the vine 

 is to be taken out by unscrewing the triangular board, and opening the sash, or shutter, 

 a more than sufficient space for drawing out any ordinary-sized plant is obtained without 

 the least trouble or chance of fracturing the shoots. It may be added, that in curvilinear 

 ground plans, some exertion of design and nicety of workmanship is required in framing 

 the horizontal shutters, so as they shall not twist, and also that they require in such cases 

 to be hinged with what are called coach-hinges. 



1644. Glazed shutters (Jig. 269.) are preferred by some to an opaque panel, the utility 

 of which must, of course, depend on the relative height of 



the pots or plants immediately within. The mode of 

 opening such shutters, and keeping them open (Jig- 270.), 

 is perfectly simple. 



1645. The back wall is in general straight or perpendi- 

 cular, and carried up one or two feet higher than the glass, 

 to shelter it from the north. (Jig. 255.) Sometimes, how- 

 ever, it is bevelled or curved to meet the sun's rays. 

 (fig. 261. 6) 



1646. The back shed (Jig. 256. a) is naturally con- 

 nected with the back wall, and in form and extent, is ge- 

 nerally regulated more by its uses as a working^shed, than 

 by the mere enclosure and covering of the fire-places and 



fuel, its original and legitimate objects. The width may be varied at pleasure, but sel- 

 dom exceeds ten or twelve feet, and the height is generally seven or eight feet in the lower 

 wall, and nearly of the same height as the back wall ; but where opening shutters are 

 formed in the back wall, for the purposes of ventilation, the upper angle of the shed-roof 

 must be kept under the level of the shutters to save intricacy of contrivance. But as these 

 shutters frequently do not communicate directly with the open air, but with passages 

 under the shed-roof, or channels in the top of the back wall, the height of the shed may 

 in such cases be made higher. In some cases, instead of shutters (Jig. 270. ), boards slid- 

 ing in grooves, or a sort of Venetian blind, or which is best, flaps held close by a cord, 

 pulley, and weight, are used ; but the great heat of hot-houses is apt to warp and derange 

 some of these contrivances. The essential part of the back shed, as respects the hot- 

 house, is the situation for the furnace and fuel, or steam-apparatus, with which no other 

 use to which it may be applied must be allowed to interfere. Sometimes back sheds are 

 not enclosed, but supported on pillars, in which case they are used for fermenting tan, 

 leaves, or dung, growing mushrooms on ridges of dung, holding pots, pease-sticks, and 

 other similar purposes. Where the range of hot-houses is situated in the middle of the 

 garden, great care must be taken, that it present nothing offensive, and that the sheds 

 behind neither resemble a row of workshops, alms-houses, brickmakers' sheds, or cattle- 

 hovels. An effectual way of preventing this, is by carrying up the walls of the sheds as 

 high as the other walls, thus completely concealing their roofs. 



SUBSECT. 6. Furnaces and Flues. 



1647. The most general mode of heating hot-houses is by fires and smoke-Jlues, and on a 

 small scale, this will probably long remain so. Heat is the same material, however pro- 

 duced ; and a given quantity of fuel will produce no more heat when burning under a 

 boiler than when burning in a common furnace. Hence, with good air-tight flues, 

 formed of well burnt bricks and tiles accurately cemented with lime-putty, and arranged 

 so as the smoke and hot air may circulate freely, every thing in culture, as far as respects 

 heat, may be perfectly accomplished. 



1648. The hot-JiouseJire-place, or furnace, consists of several parts : a chamber, or oven, 

 to contain the fuel, surrounded by brick-work, in which fire-brick (a sort containing a 

 large proportion of sand, and thus calculated by their hardness not to crumble by heat, 

 &c.) is used; a hearth or iron grating, on which the fuel is laid; a pit or chamber 

 in which the ashes drop from this grating, and iron doors to the fuel-chamber and 

 ash-pit. 



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