130 Mr. Daniell on Climate. [Feb. 



effectually be prevented by rolling mats. With this precautioti, 

 fire would be but rarely wanted in a good situation, to communi- 

 cate warmth. But in this damp chmate it may be required to 

 dissipate moisture. The state of the air should be as carefully 

 watched with this view as where a high temperature is necessary, 

 to guard against the contrary extreme. Free transpiration, as 

 I have before remarked, is necessary to the healthy progress of 

 vegetation, and when any mouldiness or damp appears upon the 

 plants, the temperature of the air should be moderately raised, 

 and free ventilation allowed. When the pots in the proper 

 season are moved into the open air, it would contribute greatly 

 to their health to preserve them from the effects of too great 

 evaporation, to imbed them well in moss or litter : as a substi- 

 lute for this precaution, the plants are generally exposed to a 

 northern or eastern aspect where the influence of the sun but 

 rarely reaches them, but which would be very beneficial if their 

 roots were properly protected. The advantage of such a protec- 

 tion may be seen when the pols are plunged into the soil, a 

 method which communicates the greatest luxuriance to the 

 plants, but unfits them to resume their winter stations. 



When a green-house is made use of, as it often is, after the 

 removal of the pots, to force the vine, the same precautions 

 should be attended to as in the management of the hot-house> 

 and the elasticity of the vapour should be maintained by wetting 

 the floor ; but after a certain period a great degree of dryness 

 should be allowed to prevail, to enable the tree to ripen its wood, 

 and form the winter protection for its buds. In this its treat- 

 ment differs from that of the tropical plants, which require no 

 such change, and to which, on the contrary, it would be highly 

 detrimental. The same observation applies to forcing houses 

 for peaches, and other similar kinds of trees. As soon as the 

 fruit is all matured they should be freely exposed to the changes 

 of the weather. 



Upon an attentive consideration and review of the subject, it 

 appears to me certain that a frequent consultation of the indica- 

 tions of the hygrometer is quite as necessary to the Horticultu- 

 rist as of those of the thermometer, and it is not unworthy of the 

 consideration of the Horticultural Society, whether correct 

 registers of the state of the climate, both in their houses and 

 out of doors, and a connected series of experiments upon the 

 modifications of which it is susceptible, might not contribute 

 something to the perfection of that art, which they are making 

 sCich honourable exertions to perfect and communicate. 



To me it will be a source of great satisfaction if any observa- 

 tions which I have made, or may make, upon the subject of 

 climate, should prove to be at all instrumental in forwarding 

 their important views. 



