150 GREENHOUSE CONSTRUCTION AND HEATING. 
seen that the fumes or products of combustion from the 
lamp or burner (at 4) ascend through a vertical tube B into 
another large horizontal tube c, placed across the top of 
the last ; from this there are only two outlets, these being 
on the lower side, one at each end, leading into two 
other vertical tubes Dp D, which are also open at the 
bottom, with a small pan beneath each to receive the 
condensed moisture, etc. The large tube co receives and 
radiates a very large amount of heat, and by the time the 
fumes from the lamp have been at any rate partially 
condensed in the tubes c and p D, what remains and escapes 
at the apertures E E is prac- 
tically innocuous. Even gas, 
of which the fumes are as a 
rule very deadly to plant life, 
may be burnt in a stove of 
this kind with little or no 
injurious effects on the occu- 
pants of a greenhouse, while 
as there is no flue or means 
of escape from the stove, the 
whole of the heat generated by the flame is utilised in the 
structure. The stove illustrated in Fig. 98 is an excellent 
example of this system. 
There are now a considerable number of different forms 
or adaptations of this stove on the market, some with two, 
three, or more cross-tubes, and others again with smaller 
tubes, open at each end to the air, placed within the larger 
heating tubes. By this means the heating surface is 
considerably increased, while the actual size of the 
apparatus remains the same. Most of these stoves are 
Fie. 97. 
