^76 THE HOT-HOUSE. [Feb. 
When a Hot-house is greatly infested, either with the Aphides or 
Thrifts, the fumigations should be repeated every third or fourth 
night, for three or four times successively. The reason and neces- 
sity of these repetitions proceed from a probability that the smoke 
cannot affect the insect in the egg, and perhaps it may not have 
sufficient power over them in other of their states; therefore a fresh 
brood may naturally be expected in a few days. 
Care of the Pines. 
Many of the Pine plants will now appear set for fruiting, which 
may be distinguished by the short leaves in their centres; from 
that time they should be moderately watered, and the house kept 
pretty warm; for when plants are kept cold at the time of forming 
their fruit, it generally causes many of them to be crooked, 
imperfect and mis-shapen. Therefore, under such circumstances, 
never let the heat fall lower than 55° of Fahrenheit, nor rise higher 
by fire-heat, than 62°: a little air should, however, be admitted, 
whenever the weather permits, and especially, on sunny warm days, 
when the heat rises to above seventy degrees. But in no case, nor 
under any circumstances, let the heat of the house fall below 52°, if 
possible. 
As some persons may be furnished with Reaumur's, and not with 
Fahrenheit's thermometer, it may be of use to give a comparative 
table of their scales, as well as the rules by which one can be con- 
verted into the other; observing, that 32° of the latter, being the 
freezing point, is equal to (or zero) of the former. 
Reaumur's. 
Fahrenheit's. 
Reaumur's. 
Fahrenheit's. 
Degrees 16 
68 
Degrees 
33 
106,2 
15 
65,8 
32 
104 
14 
63,5 
31 
101,7 
13 
61,2 
30 
99,5 
12 
59 
29 
97,2 
11 
56,8 
28 
95 
10 
54,8 
27 
92,7 
9 
52,5 
26 
90,5 
8 
50 
25 
88,2 
7 
47,7 
24 
86 
6 
45,5 
23 
83,8 
5 
43,3 
22 
81,5 
4 
41 
21 
79,2 
3 
38,6 
20 
77 
2 
36,5 
19 
74,7 
1 
34,2 
18 
72,5 

32 
17 
70,3 
To convert the degrees of Reaumur into those of Fahrenheit. 
Multiply the degrees of Reaumur by 9, and divide the product by 4; 
to the quotient add 32, and the amount will be those of Fahrenheit. 
