124 Mr. Daniell on Climate. [Feb. 



this climate, is the uncertainty of clear weather ; a circumstance 

 which art has, of course, no means to control ; no artificial 

 warmth is capable of supplying the deficiency when it occurs, 

 and without the solar beams fruits lose their flavour and flowers 

 the brightness of their tints. It has been attempted to commu- 

 nicate warmth to walls by means of fire and flues, but without 

 the assistance of glass no great success has attended the trial. 



It is well known that solar heat is absorbed by different 

 substances with various degrees of facility dependant upon their 

 colours, and that black is the most efficacious in this respect. 

 It has therefore been proposed to paint garden walls of this 

 colour ; but no great benefit is likely to arise from this sugges- 

 tion. It is probable that in the spring, when the trees are devoid 

 of foliage, the wood may thus be forced to throw out its blossom 

 somewhat earlier than it otherwise would ; but this would be 

 rather a disadvantage, as the flower would become exposed to 

 the vicissitudes of an early spring. It is more desirable to 

 check than to force this delicate and important process of vege- 

 tation, as much injury may arise from its premature develope- 

 ment. When the tree has put forth its foliage, the colour of its 

 protecting support can have no influence in any way : the leaves 

 cover the surface and absorb the rays by their own inherent 

 powers. The only known advantage which can be taken of this 

 peculiar power in dark substances, is in the case of covering up 

 fruits, to preserve them from the ravages of flies ; grapes which 

 are enclosed in bags of black crape ripen better than those in 

 white ; but I believe that it is admitted that neither do so well 

 as those which are freely exposed. 



I come now to the consideration of a confined atmosphere, 

 the management of which being entirely dependent upon art, 

 requires in the Horticulturist a more extended acquaintance 

 with the laws of nature, with regard to climate, and greater skill 

 and experience in the application of his means. The plants 

 which require this protection are in the most artificial state 

 which it is possible to conceive ; for not only are their stems 

 and foliage subject to the vicissitudes of the air in which they 

 are immersed, but in most cases their roots also. The soil in 

 which they are set to vegetate is generally contained in porous 

 pots of earthen ware, to the interior surface of which the tender 

 fibres quickly penetrate and spread in every direction ; they are 

 thus exposed to every change of temperature and humidity, and 

 are liable to great chills from any sudden increase of evaporation. 

 This part of the subject naturally divides itself into two branches. 

 The first regards the treatment of such exotics as are wholly 

 dependent upon the artificial atmosphere of hot-houses : the 

 second refers to the management of those hardier plants which 

 only require.to be preserved in green-houses part of the year, 



