176 THE HOT-HOUSE. [Feb. 
To convert the degrees of Reaumur into those of Fahrenheit: 
multiply the degrees of Reaumur bj 9, and divide the product bj 
45 to the quotient add 32, and the amount will be those of Fahren- 
heit. 
To convert the degrees of Fahrenheit into those of Reaumur: 
subtract 32 from the degrees of Fahrenheit; multiply the re- 
mainder by 4; divide the product by 9, and the quotient will be 
those of Reaumur. 
Your fires must be continued every evening and night, being 
careful in very severe weather to keep them burning and suffi- 
ciently supplied with fuel till so late a period that there can be no 
danger of the house becoming cold before morning. Indeed, unless 
your house is well constructed, there may be some severe weather 
in which it would be necessary to keep up the fires all night. 
There have been instances of careless persons entrusted with this 
work, who, in order to get to bed at an early hour, or to some idle 
frolic, have put down large and violent fires, which never fail to 
do injury to the plants, and sometimes to burst the flues: this prac- 
tice is to be carefully avoided, as a moderate and steady heat is 
what always will ensure the best success. 
The fires are to be renewed very early in the morning, and con- 
tinued until the heat of the sun is sufficient to promote a comforting 
warmth in the house; and in very cold and dark weather, it will 
be necessary to keep them burning all day. 
It is very advisable, and indeed indispensable, for the health of 
the plants, to sprinkle the flues and floor occasionally with water, 
in order to restore the parched air of the house to its atmospheric 
quality: this will not only render great service to the plants, but 
tend to weaken the power of destructive insects; for these do nof 
like a moist air, manifested by their greater increase in dry stoves, 
than in others. 
A proper degree of heat must now be preserved in the bark-bed, 
for nothing can contribute so much to the free growth of the young 
fruit, as a brisk bottom-heat: if the roots have not this advantage, 
it is impossible to make the fruits swell to any tolerable size. 
Therefore, where the bark-bed was not stirred up the former 
month, to renew the fermentation, and revive the declined heat, it 
should now be done, for the heat will consequently now begin to be 
very faint, and by stirring up the bark almost to the bottom, it will 
bring on a fresh fermentation therein; by which means the bed 
will again recover a lively growing heat, the good effect of which 
will soon appear both in the plants and fruit, provided it be done in 
due time; but if the heatis greatly decreased, and the bark decayed, 
you may augment it at the same time with about one-third or fourth 
part of new tan, otherwise defer it till next month, which see. * 
However, where the work of forking up the bark- bed appears 
necessary at this time, agreeable to the observations above mentioned, 
it should, if possible, be done in the first week in the month; for 
if it is delayed much longer, the plants and fruit will certainly, for 
want of a due proportion of heat, be much checked in their growth. 
Observe, in the first place, to take all the pots out of the bed; then 
