132 HOT-HOUSE. 
full play all round the boiler, carrying the flue about forty 
or fifty feet through the house, that no heat may be lost; 
attach two pipes to the surface or top of the boiler, if it is to 
heat right and left, but only one pipe if the heat is to be 
carried in one direction ; distribute the pipe wherever re- 
quired, giving it an ascent of not less than sis inches to the 
fifty feet, more if it can be done — return the pipe, entering 
it into the lowest part of the boiler ; the greater the ascent 
and descent, the more rapid the circulation. The joints of 
the pipe are closed by soft hemp rope, firmly rammed up and 
closed by a mixture of white and red lead made to the con- 
sistency of putty. These joints are preferable to those of lead, 
which expand and contract by strong heat, requiring to be 
hammered up frequently during the season — they can also 
be very readily taken apart, when removal or alteration is 
required. It must be observed that air tubes have to be in- 
serted into the highest part of the pipes at each extremity, 
and also one over, or near the boiler, for the conveuiency of 
supplying water. If the pipes diverge from the boiler to two 
extremes, each extremity must be on a level, which other- 
wise will cause an unequal diffusion of heat. 
EXAMPLE. — If a house to the right of the boiler one hun- 
dred feet long has the extreme end of the pipe elevated one 
foot above the level of the boiler, a house fifty feet long to the 
left must have the same elevation, otherwise the heat will be 
the greatest where the pipe is liiglicst. 
This we consider the most economical method of heating by 
hot water, and it is by far the most simple — simple indeed 
in every part, though volumes have been written on the sub- 
ject. 
Bark Pit. — We consider such an erection in the centre 
of a hot-house a nuisance, and prefer a stage, which may be 
constructed according to taste. It should be made of the 
best Carolina pine, leaving a passage all round, to cause a 
free circulation of air. The back and end paths may be 
about two feet wide, and the front three feet. The angle of 
the stage should be parallel with the glass, having the steps 
from six inches to one foot apart. 
Where there are some large plants, they may stand on 
the floor behind the stage, or on tressels, according to their 
heicht. 
