240 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 



drainage, they must still be very far from the internal tempera- 

 ture of the house, a fact which requires no calculation to 

 prove it. And hence, although the vine, of all other fruit-bear- 

 ing plants, will accommodate itself to circumstances apparently 

 the most unpropitious, and will stand forcing in mid-winter bet- 

 ter than any other fruit we can place into a hot-house, still, it 

 cannot be expected that we shall arrive at anything like perfec- 

 tion in its produce by winter-forcing, under the present methods 

 of cultivation. And we know that, whatever can be said in 

 favor of carrion-borders, no mere aggregation of organic matter 

 will suffice for the production of grapes, especially in winter, 

 if the principle of life be impotent, and the functions of the plant 

 impaired, whether by natural or artificial causes ; and nothing 

 is more likely to weaken the one, or impair the other, than 

 placing the roots of vines in an ice-house, and the branches in 

 an oven. 



In close connection with the foregoing subject is a system 

 which has engaged no inconsiderable share of attention in Eng- 

 land, and may probably be employed with equal advantage in 

 this country. The system to which I allude, is forcing by hot 

 walls covered with glass. It has now become common to build 

 garden walls hollow, and heat them with hot water, with flues, 

 or both, and by covering them with temporary roofs, consisting 

 either of spare sashes on hand, or by having sashes made for 

 the purpose. By this means, a range of portable houses may 

 be constructed upon any walls adapted for that purpose, at a 

 very inconsiderable expense, compared with that of permanent 

 houses. (See Part I. Construction of Walls.) 



Fig. 50 shows an end section of the wall ; a a, ties across the 

 wall, at regular distances, for the purpose of strengthening the 

 fabric ; b, the pipes for hot water, or the situation of the flue, if 

 that method of heating be adopted ; c, the furnace and boiler, 

 placed in a recess of the wall,' as shown in the ground plan ; d 

 d, the returning pipes, or the position of the returning flue, if 

 pipes are not used ; e, the projecting support for the sashes 

 under the coping; /, the lower supports for the sashes, consist- 

 ing of timber posts driven into the ground, that no obstruction 

 may be presented to the roots of the vines by a brick wall ; g, 



