438 



PITS AND FRAMES. 



be made to break, and that all except 

 one or two of the leading shoots will be 

 weak and dwindling. The remedy for 

 this is, I apprehend, so to accelerate the 

 growth of the roots as to enable them to 

 keep pace with the branches, when the 

 supply of sap will be adequate to all the 

 demands of nature. The bearing wood 

 may also by these means be trained to 

 any reasonable length, for every eye will 

 receive a due supply of nutriment : each, 

 therefore, will break regularly, and each 

 make strong and vigorous shoots, and 

 consequently be capable of bearing fruit. 

 By this system, too, grapes may be 

 brought to a ripe state in much less time ; 

 for, instead of the slow and cautious pro- 

 ceeding required for bringing out the eyes 

 at the commencement, a high degree of 

 temperature may be kept up in the house ; 

 for, as the roots are taking up, in conse- 

 quence of their rapid growth, a larger 

 quantity of nutriment, the supply of sap 

 is more rapid ; and therefore a more rapid 

 growth of the branches may be permitted." 



a doors for introducing the dung c ; 

 b the border in which the vines are 

 planted ; d d iron joists supporting a 

 covering of slates ; e trellis to which the 

 vines are trained. 



§ 2. — PITS HEATED BY SMOKE FLUES, 

 TANKS, HOT -WATER PIPES, AND 

 STEAM. 



The idea of abandoning tan and other 

 fermenting matter for the production of 

 bottom heat is no new feature in horti- 

 culture, for we find substitutes employed 

 towards the latter end of the last century, 

 (vide section Various Modes of Heating, 

 &c.) ; and we find, so far back as 1823, 

 Mr Stewart, at that time gardener at 

 Valleyfield, near Culross, growing pines 

 in a pit heated with flues. This pit was 

 provided with a hot-air chamber, from 

 which tubes conducted the heated air 

 into the pits, not only for keeping up a 

 proper atmospheric heat, but for regulat- 

 ing the bottom heat also. These tubes 

 had stoppers that were taken out or not 

 according to circumstances. They were 

 placed along the back and also the front 

 of the pit, and were 4 feet asunder. It 

 appears, also, that prior to the above date, 

 both Mr Kent and Mr T. A. Knight had 



pits heated upon much the same prin- 

 ciple. 



It has been stated in objection to pits 

 heated in this manner, that a dry and 

 uncongenial heat is produced. Such is, 

 however, not the case ; for, by watering the 

 sand upon which the plants are placed, 

 the atmosphere of the house might be 

 kept at the point of saturation, if desired. 



To render this pit perfect, we would 

 suggest the following improvements, — 

 namely, the carrying one flue through 

 it along the centre instead of two, and 

 over it placing a hot- water tank, extend- 

 ing the whole length and breadth of the 

 pit, or the making the water to circulate 

 round in a wooden tank or gutter along 

 the front, and returning in the same 

 manner along the back. A small boiler 

 should be placed over the furnace, and in 

 fact forming its roof and sides. By this 

 means a greater length could be heated 

 by one fire ; and, to prevent loss of heat 

 by its being absorbed by the surrounding 

 side walls, we would suggest that these 

 be built double, having a vacuity between 

 to be filled with air in a quiescent state. 

 The smaller also the pit or air-chamber 

 is, the better ; and air should be admitted 

 to it from without, under proper regula- 

 tion. This supply of atmospheric air is 

 to be admitted through tubes, placed 

 through and up the outer sides of the 

 back and front walls, as shown in many 

 instances in this work. This would pro- 

 duce a regular circulation ; and instead of 

 the same air being made to pass down 

 from the interior of the pit — which it 

 would do if at any time colder than the 

 air in the vault — and thus circulate only 

 the same air over and over again, we would 

 have a constant supply of pure air from 

 without, which would be beneficial to the 

 plants, while the foul and heated air 

 would escape through the roof whenever 

 the sashes are opened. To lessen the capa- 

 city of pits already built and to be heated 

 upon this principle, they may be nearly 

 filled with hard water-worn stones or very 

 rough gravel. 



In the case of this pit we have hot dry 

 air and hot moist air combined, which, 

 working together, will make a good 

 healthy atmosphere for ordinary pur- 

 poses; indeed, there will always be a 

 sufficiency of humid air. To counteract 

 this when a drier air is required, cut off 



