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LXI. Observations on the Blacking of Garden Walls, as it af- 

 fects the ripening of Fruits. In a Letter to the Right Hon. 

 Sir Joseph Banks, G. C.B. P. R. S. $c. By Mr. Henry 

 Dawes. 



Read November 2, 1818. 



Sir, 



I tak e the liberty of communicating to you my remarks 

 on a garden wall, on which I have been making experiments 

 at Slough. It faces the south, and against it, about the mid- 

 dle, a young Grape vine is trained. Two years ago, I co- 

 vered a portion of the wall with 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 season 

 was so unfavourable last year, that scarcely any out-door 

 Grapes came to perfection, but those on the blackened part 

 of the wall were much finer than those on the plain part. 

 This year the success of my experiment has been complete. 

 The weight of fine Grapes gathered from the blackened part 

 of the wall was 20lb. 10 oz., while the plain part yielded only 

 71b. loz., being little more than one-third of the other. 

 The fruit on the blackened part of the wall was also much 

 finer, the bunches were larger, and ripened better than on the 

 other half; the wood of the Vine was likewise stronger and 

 more covered with leaves on the blackened part. 



It is a generally known fact, that a black unpolished sur- 

 face absorbs more rapidly than other colours the sun's rays, 

 and thereby becomes sooner heated. It is equally well 



