42 THE GRAPE. 
any noxious gases, and if constructed on the best plan, 
may be placed on the credit side cf expenses, there is also 
a steady heat in the working, and a sufficiency of bulk in 
the quantity of water, which, when once put in moticn, 
continues to flow with increased or lessened velocity, ac- 
cording as the fire is kept up, and for some time esen 
after no further heat arises from the furnace. There have 
been different methods adopted, as reservoirs for circula- 
ting hot water, such as lining the inside of brick flues with 
cement; tanks of wood ; tin or sheet iron troughs, with 
the tops left loose, to be ‘tov or gs as circumstances 
may dictate; circular copper, tin and cast iron 
pipes. The cemented flue is cEeidiconbl, as the material 
is so non-conducting, that there is great loss, and the 
cement is also liable to crack, which causes leakage. The 
open tank, and trough is well enough for a propagating 
house, which is generally small, and kept very damp, but 
is not suitable for a grapery, in which is required, a moist 
or dry atmosphere, eon to the different stages of 
growth; this plan also oceupies much space, and looks un- 
sightly Tin pipes are not advisable from their tendency 
_to corrode, and unendurable qualities. Zine softens when 
_ hot, and is next to useless, copper if made strong enough 
to resist hard knocks, and be really serviceable is very 
_ expensive, so we are driven to the last substitute, east 
iron, which answers every purpose, is lasting, erected 
_ comparatively cheap, strong, and the different lengths are 
readily cemented, the joints becoming as firm and tight as 
any other part. The construction of boilers for this pur 
pose is aiso various, and there is a great difference in the 
consumption of fuel, according with the ratio of heat dis- 
wee was com 
