[ 459 ] 



LXXXVIII. Upon the Effects of very high Temperature on 

 some Species of Plants. By Thomas Andrew Knight, 

 Esq. F. R. S. $c. President. 



Read December 7th, 1819. 



Having constructed a forcing-house for the purpose of at- 

 tempting the culture of the Mango, and a few other species 

 of tropical fruits, I have endeavoured to ascertain, with 

 accuracy, the advantages and disadvantages, of employing 

 very high temperature during the day in bright weather, and 

 of comparatively low temperature, during the night, and in 

 cloudy weather ; and I communicate the following account 

 of my experiments, considering the results to have been ge- 

 nerally very favourable, and where unsuccessful, not wholly 

 uninteresting. 



A fire of sufficient power, only, to preserve in the house a 

 temperature of about 70°, during summer, was employed, 

 but no air was ever given, nor its escape facilitated, till the 

 thermometer, perfectly shaded, indicated a temperature of 

 95° ; and then only two of the upper lights, one at each end, 

 were let down about four inches. The heat of the house was 

 consequently sometimes raised to 110°, during the middle 

 of warm and bright days, and it generally varied, in such 

 days, from 90° to 105°, declining during the evening to 

 about 80°, and to 70° in the night. 



Late in the evening of every bright and hot day, the plants 

 were copiously sprinkled with water, nearly of the tempera- 



