180 



HEATING AS APPLIED IN HORTICULTURE. 



boiler is cast-iron with a malleable-iron they pass through the breastwork of the 

 cover bolted on; but its greatest peculiarity building, and empty themselves into the 



Fig-. 231. 



Fig. 233. 



is what is called the combustion-pipe 

 a, fig. 231, which forms a current for 



232 the smoke to 



pass upwards 



through the 

 centre of the 

 boiler. What 

 effect this may 

 have on the 

 consumption of 

 the smoke we 

 could not learn, 

 but that it 

 must add to 

 the heating- 

 power is sufficiently clear. A large 

 surface also of the boiler is exposed to 

 the action of the fire, and as it con- 

 tains only a small quantity of water, it 

 consequently heats rapidly, b, fig. 230, 

 is the flue door for extracting soot from 

 around the boiler ; c a similar door at the 

 bottom of the chimney, for a like pur- 

 pose. Our figures show a plan of the 

 boiler, and also two perpendicular sections 

 taken at right angles through it. 



Williams' boiler — fig. 233 — is of excel- 

 lent construction, formed of wrought-iron 

 plates securely riveted together. To us 

 the great improvement in this boiler over 

 most others is the contrivance for clean- 

 ing it out — a most essential point, and 

 one sadly neglected. The square pipes 

 a a, to which the cocks are attached, are 

 secured to the front part of the boiler by 

 flanges, so that they can be removed with 

 ease when the boiler is to be cleaned out ; 



stoke-hole. A man-hole, b, is placed on 

 the top in the usual manner, but is some- 

 what larger than usual, which is an im- 

 provement; and when the square pipes 

 are removed, the interior can be com- 

 pletely cleaned out. The flow-pipes c c 

 branch from a nipple on the top fur- 

 nished with sockets, to which the pipes 

 are attached. The fire is made at d in 

 the middle of the boiler, which forms 

 the sides and roof of the oven, the flames 

 passing round the outsides which form 

 one side of the flues; e is the return-pipes; 

 the top is level, and projects over the 

 tops of the side flues, thus not only secur- 

 ing them, but also gaining an additional 

 degree of heat. Altogether, we consider 

 this one of the very best of boilers. 



Weeks and Co.'s improved boiler. — These 

 enterprising hothouse-builders have re- 

 cently invented an improved boiler, which 



they have ex- 



Fig. 234. 



as merit to recommend 



hibited in the 

 Crystal Pal- 

 ace, forming 

 one of the 

 few speci- 

 mens pre- 

 sent there of 

 implements 

 adapted to 

 horticulture. 

 This boiler, 

 of which the 

 annexed cut, 

 fig. 234is a re- 

 presentation, 

 has much no- 

 velty as well 

 it. It is con- 



