266 On Improving the Productiveness of Fruit Trees. 



applicable to fruit-trees in general. It is curious that both 

 authors seem to have been impressed with the idea, that 

 they were the discoverers of that method, and it is interesting 

 to see, how they both meet in the same road. The German 

 writer observes, that the proper size of his bark-ring is a 

 quarter of an inch in width ; Mr. Williams relates, that he 

 made his annular excisions first half an inch broad, but he 

 found, in the succeeding year, that the Vines which had 

 undergone that discipline, did not push freely, and seemed 

 to be injured. The alburnum had been too much exposed. 

 He, therefore, reduced the rings to between one eighth and 

 two eighths of an inch in width, which is very nearly Mr. 

 Hempel's dimension, and the trees did well. Those Vines 

 were in the open air ; to such as were in a forcing-house, 

 and sheltered from the weather, it did not seem prejudicial to 

 make the excision wider, for the bark also was in those houses 

 more quickly reproduced. Mr. Williams lays a parti- 

 cular stress upon the entire removal of both the outer bark, 

 or cortex, and the inner, liber, in making those rings ; for if 

 you leave any part of the latter, the bark forms soon again, 

 and all your trouble is lost. Mr. Hempel likewise inculcates 

 it as a precept, that both the outer and inner bark must be 

 entirely stript off, so as to leave the wood, or alburnum, 

 perfectly bare. They both state, that the fruit in con- 

 sequence of ringing, or annular excision, becomes much 

 larger ; and Mr. Williams adds also, better flavoured, and 

 that it ripens more quickly. He explains these effects by 

 Mr. Knight's theory of the downward circulation of the 

 sap ; Mr. Hempel attributes them to a retarded motion. 

 There is a very important consequence, which the latter 



