206 



HEATING AS APPLIED IN HORTICULTURE. 



their houses, on account of the interrup- 

 tion of the doorways. This is easily got 

 over by connecting them on each side of 

 the door, by means of a leaden pipe bent 

 so as to pass under the level of the floor, 

 and rising again to the tank or gutter on 

 the opposite side. This dip must only 

 be made once, for reasons hereafter given. 

 — ( Vide section On Causes op Circula- 

 tion, and also fig. 246.) Wooden tanks are 

 excellent when they have to be placed in 

 an elevated position. In such cases they 



are better than brick, as being less ex- 

 pensive ; but in a case like the present, 

 where the tank rests on a solid founda- 

 tion, we think brick or stone preferable. 



Lawrence's system of tank-heating. — As 

 an instance of employing earthenware 

 tanks, we may notice one described in 

 " The Gardeners' Chronicle," which was 

 erected at Cirencester, and with complete 

 success, although upon a larger scale than 

 ordinary. The diagram, fig. 270, will 

 show its operation : a is the boiler upon 



Fig. 270. 





0 



J-/ 







/ 



0 







the double cylindrical principle, placed 

 about midway between the hothouse and 

 pits heated by it. The hothouse is divided 

 at b in the ground-plan, the smallest 

 division being that nearest the boiler, and 

 used as a stove, while the other is used 

 as a vinery. They can be heated together 



Fig. 271. 



tion, 



They 



or separately, as 

 required. Un- 

 der the footpath 

 at c is a brick 

 tank for holding 

 the rain water 

 that falls on the 

 roof. The gut- 

 ters are of earth- 

 enware, and 

 shown in sec- 

 are 15 inches 



broad and 5 inches deep, and in lengths 

 of 15 inches each. The tiles at the angles 

 or turns are of a different mould, and are 

 in three pieces, one for each angle, there 

 being no joint at the angle. The tiles at 

 the boiler end are also different, having 

 projecting collars for the more readily 

 joining them with the pipes from the 

 boiler a in ground-plan. The flow and 

 return gutters are connected at two 

 points in ground-plan, //, so that the cir- 

 culation may be confined between either 

 and the boiler : " at these points the 

 gutters are covered by a wooden frame 

 instead of a tile, in which is fixed a mov- 

 able cover which exposes the plugs, by 

 means of which the circulation is diverted 

 across the house, or extended at pleasure 

 along the entire range." As the ground 



