302 



THE GAKDENER'S ASSISTANT. 



it reach 83° or 84°, the highest; the range 

 should be limited generally to 8° or 10°, that 

 is 4° or 5° above the mean in the day, and as 

 much below it in the night; thus, when the 



L'88 —Pine-apples (Jamaica). 



mean temperature is to be 75°, the lowest at 

 night should be 70°, and the highest in the day 

 80°. On this principle the following table, ex- 

 hibiting the temperature which we consider 

 most suitable for the Pine -apple, has been 

 calculated: — 





9 



fa 



JZ 

 oS 



< 



3 



JS.-i 



a 

 >-» 



87° 



87° 



fci 



3 

 < 



87° 



1 



1 

 83° 



> 



o 

 Z 



78° 



6 



0J 



Highest ii 



day 



the ) 



night 



75 



77° 



80° 



83° 



77° 



Lowest at 



65 



67 



70 



73 



75 



77 



79 



79 



77 



75 



70 



65 



Mean 





Til 



72 



75 



78 



80 



82 



83 



83 



81 



79 



74 



71 



By sun-heat, with an additional amount of 

 ventilation, the temperature may be allowed to 

 rise 10° higher than the maxima indicated in the 

 above table. This would limit the highest tem- 

 perature by artificial means and sun-heat com- 

 bined to 97°; the house may, however, in summer 

 be shut up at 100° in the afternoon, when the 

 intensity of the sun's rays have diminished so 

 much that, instead of the temperature rising 

 higher, it will only remain stationary for some 

 time and then gradually decline. 



Excessive heat in the day must be counter- 

 acted by a gradually increased amount of ven- 

 tilation, for if the temperature can be kept 



within proper limits the sun's rays should by 

 no means be excluded. In certain cases when 

 air cannot be admitted so as to have the de- 

 sired effect, as in very hot weather, or where 

 the construction of the house is such 

 that with all the air that can be given 

 the temperature cannot be kept below 

 100°, then a shading of some thin 

 material may be employed, in order to 

 prevent the air of the house from rising 

 above that point. When the external 

 temperature is as high as 80°, or nearly 

 so, air may be given freely, provided a 

 rush of it is not suddenly admitted when 

 the atmosphere of the house is much 

 warmer. The greater the disparity 

 between the heat of the internal and 

 external air, the more cautiously should 

 the latter be admitted. When the sky 

 is clear, with bright sun, and when at 

 the same time the wind is very cold and 

 dry, it may be advisable to use a slight 

 shading rather than to introduce much 

 air from outside, unless it can be warmed 

 previous to its coming in contact with 

 the foliage, when it may be admitted 

 to any desired amount. 



On cold nights a warm covering would 

 be highly beneficial as regards both the 

 temperature and moisture of the internal 

 A single layer of mat will prevent radia- 

 tion from the glass to a considerable extent; 

 but a much warmer covering would not only 



air, 



Fig. 1089.— Meudon Pine-house. 

 aa. Ground-line, b. Hot-water pipes for top heat, c, Bed of peat soil in 

 which the Pine-apples are planted, d. One of the iron bars for supporting 

 the boarded flooring on which the bed of soil rests, e. Vault filled with 

 stable-dung and leaves. /, Foot-path, gg, Air-holes, h, Shelf for Straw- 

 berries, i. Iron rail over which the straw mats are hung when the house is 

 uncovered. 



economize fuel, but also greatly benefit the 

 plants, by preventing the air from becoming 

 dry to an injurious degree. 



