•292 Transactions of the Horticultural Society. 



to supply it is, by keeping the floor of the house and the sur- 

 face of the flues continually wet, when the temperature is high. 

 " An atmosphere," Mr. Daniell observes, " of great elasticity, 

 may thus be maintained in a way perfectly analogous to the 

 natural process. When steam is employed as the means of 

 communicating heat, an occasional injection of it into the air 

 may also be had recourse to ; but this method would requue 

 much attention on the part of the superintendant, whereas the 

 first cannot be easily carried to excess." 



To obviate the evil effects of cold nights in the Winter season, 

 Mr. Daniell suggests the idea of double glass. " The lights 

 of many frames, which are not commonly in use in Winter, 

 might, without much trouble, be fitted to slide over the hot- 

 houses during the severe season ; and in the Spring, when they 

 are wanted for other purposes, their places might be supplied 

 at night by mats or canvas." 



The atmosphere of the green-house should be treated like 

 that of the hot-house, but not to the same extent. 



Mr. Daniell concludes by observing, that a frequent consult- 

 ation of the indications of the hygrometer is quite as necessary 

 to the horticulturist as those of the thermometer. Undoubt- 

 edly, the hygrometer may be consulted with advantage ; but 

 if the gardener, whenever he maintains a high degree of heat 

 in the hot-house, takes care to have the paths flooded with 

 water, three or four times a-day, he cannot be far wrong ; for 

 the atmosphere will take up a certain degree of moisture, ac- 

 cording to its temperature, and the remainder on the floor 

 can do no harm. In this respect there is an important dif- 

 ference between supplying heat and supplying vapour ; heat 

 may be easily overdone, but not vapour, unless it is supplied 

 from a boiler, in the form of steam. The safe course for the 

 gardener to pursue, is to maintain a good heat, whether by 

 the sun or fire, and keep his hot-house floor continually moist, 

 He will thus maintain, as Mr. Daniell observes, " in a way 

 perfectly analogous to the natural process," an atmosphere of 

 the natural and proper degree of humidity. This has been 

 done by various gardeners with whom we are acquainted, for 

 many years, in some hot-houses for twenty years ; and, as an 

 instance, near us, we may mention the Comte de Vandes's 

 garden, Bayswater, where it has been practised since 1816, 

 and where the plants have been for that time, and now 

 are, in a state of luxuriance not to be surpassed. No 

 hygrometer was ever used there, nor can there be much 

 occasion for using it, but for the sake of experiment. At 

 any rate, a gardener not having an hygrometer should not 

 assign that as a reason for not having the atmosphere of 



