46 THE GRAPE. 
tween plants ayd animals is in this respect the same, and 
every body wh» is possessed of ordinary observation must 
be able to disesrn how different is the air that is raised in 
temperature }]-y a red-hot stove, even though a vessel of 
water be kept upon it, to what it is when raised to the 
same temperature by the sun’s power. We also know, 
that if we were able to control other cireumstances accord- 
ing to our wants for the time being, success would more 
often attend our operations, providing we could exactly 
imitate the warmth of nature. If this be true, it must 
then be certsimly to our own interest to approach as near 
as we can to this desideratum. To come to our point, a 
ious flue gives a greater surface exposed to the ac- 
fon of the heet, without becoming hot enough to bring 
about so much chemical action as to burn the air inside of 
the house, while a small one is sure to do so, at any rate, 
in that part next to the furnace. To be effectual in this 
respect, a flue ought not to be less than eighteen inches 
high, by twelve inches wide in the clear; and if raised up 
aha — supports inderneath at intervals on the length, 
fire-proof tiles to form the bottom, so much the better, 
Sipe WEL Ear a Ee out the heat on all si The 
furnace sught to be not 'esr than eighteen inches wida, and 
equal height, independert or ihe arch above, and two feet 
long. A furnace of these dimensions is qualified to work 
ahouse of forty to fifty feet long, by twelve or fourteen 
feet wide, the fine being concucted along the front and twe 
ends. retreend the length will reed two fires, and so on in 
ic>. When two furnaces are required, there may 
he one piaced at each end of the house, and conveyed ta 
the same chimney, midway in the back wail, so as to unite 
inte one outlet; but in such case there onzht to be an 
_ seute level upwards at the place of unien, cr the twe 
