HOT WATER. 315 
Mr. Corbett, foreman at Pontey’s nursery garden, Ply- 
mouth, introduced a mode of employing hot water as a 
means of heating. From a common boiler proceeds an up- 
right tube, and this tube leads to a continued series of 
open gutters. Heat being applied to the boiler, the water 
rises in the tube and flows forward in the gutters, giving 
out moisture in proportion to the degree of heat. As the 
water cools or becomes more dense or heavy, it gradually 
falls back to the bottom of the boiler. 
Mr. Rendle, of Union Road Nursery, Plymouth, has 
also introduced a mode of heating, in which he employs 
tanks instead of pipes, or gutters, for both surface and bot- 
tom heat. These tanksare formed of wood, brick, stone, or 
cast iron. When formed of wood, they require to be made 
of good sound plank, not less than two inches thick, pro- 
perly jointed, and are usually covered with slates. If they 
are formed of stone or brick, the insides require a thick 
coating of Roman cement, and for covers, stone, slate, or 
brick pavement is employed. The cast iron tanks have 
corners of the same materials. 
When only one tank is fitted up in a house or pit, a 
division is made along the centre, leaving an opening at the 
end farthest from the boiler, for the water to flow through, 
the hot water or flow pipe from the boiler being fixed to 
the end of the tank on one side of the division, and the 
cold water of return pipe to the boiler to the end, on the 
opposite side of the division. When two tanks are used, 
they are joined to the flow and return pipes respectively, 
and united at the extreme ends. In pits, the tanks may 
be carried round the sides and ends of the pit, with a divi- 
sion between the flow and return pipes. 
The principal advantage of the application of this mode 
of heating consists in the production of bottom heat 
