Transactions of the London Horticultural Society. 407 



heat which might otherwise prove fatal to the blossom. On the other hand, 

 when the fruit is swelHng it is of equal importance to keep the surface of the 

 border dry, as the temperature both of the soil and atmosphere is then in- 

 creased, which contributes much to improve the size and quality of the fruit. 



" When, however, the borders are so thickly covered with vegetables as 

 almost to prevent the access of the solar rays to their surface, such covering 

 will contribute much to lower the temperature of the soil, and of the at- 

 mosphere in contact with the wall. To ascertain the extent to which this 

 might take place, the author made the following experiments on a border 

 covered with a strong crop of cauliflower, which completely shaded the 

 surface. He took a thermometer and inserted its naked bulb about half an 

 inch into the soil of the border, where it was covered with the vegetables. 

 A second thermometer was laid on the surface of the border ; and a third 

 was placed in close contact with the wall. A similar arrangement was, at the 

 same time, made with three other thermometers in another part of the border, 

 which was uncropped, and fully exposed to the sun's rays. The border itself 

 was 12 ft. wide, and the wall of about the same height in feet. On the 10th 

 of May, 1829, the author made four observations of these six thermometers, 

 between 5 o'clock of that day, and 4 o'clock of the next, viz. at 5 a. m., 1 

 P. M., and at 10 p. nr. of the 10th.; and at 4 a. m. of the llth. The results 

 of these observations he has given in a tabular form, of which a copy is ex- 

 hibited. 



May, 1829. 



Cropped 



Bordei 



• 



Uncropped B 



order. 



Time of Observation. 



hS.s 



= ■11 

 s « & 



1-S 



S 15 a; 

 g ° " 





Temp, of soil 



half an inch 



below naked 



surface. 







5 A. M 



o 



35 

 71 



54 

 52 



16 



19 



o 



68 

 69 

 69 

 60 



1 



o 



58 

 76 

 60 

 59 



18 



17 



o 



59 



86 

 58 

 55 



27 



31 



o 



70 

 96 

 81 

 70 



26 



26 



o 



57 

 113 



68 



58 



56 

 55 







62 

 104 



m 



60 



42 



44 



1 p. M 



10 P. M 



4 A. M. 



Increase of temper- 

 ature from 5 A. M. 

 to 10 p. M 



Increase of temper- 

 ature from 10 P.M. 

 to 4 A. M 





" From this table it will be seen that at 1 o'clock p. m. the close crop of 

 cauliflowers occasioned a reduction of 18° of temperature on the wall, as 

 compared with that of the wall of the naked border : at 10 o'clock in the 

 evening the difiference of temperature between the two portions of wall was 

 8° ; and even at 4 o'clock on the next morning the difference was 5°. On 

 the 29th of May the cropped border was 4° lower than the naked one, at the 

 depth of 12 in. beneath the surface. 



" This effect of cropping, in lowering the temperature of the atmosphere, 

 will, however, be much less when the sunshine is little and partial through the 

 day ; and when the^day is wet it will not be observed. The colour, too, of 

 the soil will influence the result, a dark soil becoming much hotter than a light- 

 coloured one, when exposed in the same manner to the solar rays. 



" Vegetables in borders are least injurious to wall trees when they are 

 planted in rows at right angles to the wall, and at double the distance usually 



