194 



liOYAL nOHTTCULTUKAL SOCIETY. 



doubted, who has time carefully to observe all changes, and in 

 whom every confidence can be placed, as having no previous pre- 

 judices that could warp his judgment, and so prevent him having 

 the full benefit of all his perceptive faculties ; secondly, that 

 the experiments could be tried in a suitable locality ; thirdly, 

 that the place should be the one where the experiments 

 could be tried at the least possible expense. I think that all 

 who know the garden of the Society at Chiswick, will join 

 with me in thinking it offers all these advantages, — in its staff 

 employed under the Garden- Committee — in its climate, as 

 we are told that in July the valley of the Thames is as warm 

 as any part of England, not excepting the southern coast of 

 Devonshire and Cornwall ; and since the garden has all the sorts 

 of houses required for the experiments, it would only need a light 

 expense, such as making a warm border, buying wall-sheeting, and 

 supplying the thermometers to carry out any experiments that 

 might be required. I am one, if more can be found, willing to join 

 in the expense of the following experiments, say, for two or three 

 years. 



That the maxima be taken each day and the minima each night, 

 — in the open air, in the shade, on a south wall exposed to the sun, 

 on a south wall well sheeted up each night, as also during the day, 

 if required, which practice is to be noted, — in a heated border in 

 the open ground at the same depth, both borders to have planted 

 in them wall-trees and standards ; the sheeted-up wall to be also 

 used in like manner ; in the orchard-house, glass wall, in the 

 lean-to vinery, aud large conservatory. In each case the progress 

 of the crop to be mentioned, and when fire-heat is used in those 

 that have it. My reason for making this proposal is, because 

 I think we do not fully realize the power of sun-heat any more 

 than the advantages of border-heat. Who was prepared to find 

 what the experiment of this year has shown, that a peach-tree or 

 vine planted against the south wall at Chiswick would, during the 

 warm sunny days, have had a much higher temperature than was 

 required to bring the crop of grapes to a successful maturitv in 

 the large conservatory ? Turning to the minima table, I think 

 there is every probability that if a sheet had been employed to 

 check the loss of heat by radiation, we might have said as much 

 for the night temperature also. The disadvantage of unheated 

 glass walls is, that the sun in spring advances the trees, and yet 

 the glass is not able to prevent during the night the injury from 

 low temperatures caused either by frost or radiation during clear 



