162 OPEN Am GKAPE CTJLTUEE. 



on a garden wall, on wliicli I have been making 

 experiments at Slongli. It faces tlie south, and 

 against it, about tlie middle, a joung grape vine is 

 trained. Two jears ago I covered a portion of tbe 

 Avail witli thick black paint. The vine was divided 

 into two equal parts, one half was trained on the 

 painted, and the other on the plain wall. The sea- 

 son was so unfavorable last year, that scarcely any 

 out-door grapes came to perfection ; but those in the 

 blackened part of the wall were much finer than those 

 on the plain j^art. This year the success of my expe- 

 riment has been complete. The weight of fine 

 grapes gatiiered from the blackened part of the wall 

 Avas 20 lbs. 10 oz., while the plain part yielded only 

 7 lbs. 1 oz., being little more than one-third of the 

 other. The fruit on the blackened part of the Avail 

 Avas also much finer, the bunches Avere larger and 

 ripened better than on the otlier lialf ; the wood of 

 the vine was likcAvise stronger and more covered Avith 

 leaves on the blackened part. 



'' It is a generally knoAAm fact, that a black, unpo- 

 lished surface absorbs more rapidly than other colors 

 the sun's rays, and tliereby becomes sooner heated. 

 It is equally Avell knoAvn that surfaces Avhich absorb 

 heat more quickly, part Avitli it more easily Avhen the 

 source of lieat is AvithdraAvn, and cool quicker. In 

 the summer time, Avhen the days are long, the Avall 



