184 THE HOT-HOUSE. [FEB. 



the cavities of the roof, particularly those between the squares of 

 glass, filled with moisture. 



The Aphides may be destroyed with a gentle fumigation ; but the 

 Thrips and Coccus hesperidum require a smoke so strong, that a 

 person cannot distinguish an object farther than at the distance of 

 five feet. 



When a hot-house is greatly infested either with the Aphides or 

 Thrips, 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 th"e smoke 

 cannot affect the insect in the egg, and perhaps it may not have suf- 

 ficient 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 

 misshapen. 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 



