HOT-HOUSE. 131 
so deep ; or where there is only one door in the house, a 
stock-hole three and a half feet deep will be enough, which 
should be built like a cellar, to keep out any under water. 
In all instances, pass the first flue to the front of the house, 
over which have a close table, covered with two inches of 
sand, and, by keeping it moist, will afford a very congenial 
heat to young and valuable plants. Likewise over the fur- 
nace have a frame in the same manner, which will be found 
useful for propagating. Any part of the furnace or flue that 
is under the floor of the house should have a vacuity on both 
sides to let the heat pass upward. 
Furnaces and flues on the above construction are the most 
simple in arrangement, and the easiest to manage at all times. 
But where capital, taste, and practical science can be united, 
the more elegant disposition of heating by hot water is now 
universally adopted in extensive glass structures, and will 
soon be generally adopted in the dwellings of the better 
class. We have used it in every variety of form and struc- 
ture for the past twelve years, and have now five green- 
houses, each over one hundred feet long, heated by it, using 
every variety of pipe and form of boiler ; have also used 
wooden and cement tanks. Sand beds heated by it for pro- 
pagating upon. It cannot be economically used in green- 
houses under sevent3 T -five feet long, and sixteen to thirty 
feet wide. In all erections for plant or grape culture, at, or 
over that extent, the best and cheapest method of applying 
artificial heat is by the diffusion of hot water through cast 
iron or copper pipes, of three or four inches in diameter. The 
boiler may be of any size, from five to fifteen gallons — of 
any shape, from a pancake to a puncheon ; though that best 
adapted to the exposing the greatest surface to the fire is to 
be preferred. We use what is termed the saddle boiler, and 
also the double cylinder boiler, preferring the latter, which 
holds about ten gallons, and will supply heat enough for two 
green-houses, each one hundred feet long, or will supply a 
green-house of one hundred feet in length, and a hot-house 
fifty feet, and from sixteen to twenty feet wide, using four 
inch pipe, at a cost of about 8250, including labour and 
materials. Its erection is perfectly simple, and can be done 
by any good bricklayer and handy labourer : build the boiler 
in the centre of the furnace, with its bottom about twelve or 
fourteen inches above the fire bars ; allow the heat to have 
