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Account of some experiments on the ascent of the sap in trees. In a letter from Thomas Andrew Knight, Esq. to the Right Hon. Sir Joseph Banks, Bart. K. B. P. R. S

1832; Royal Society; Volume: 1; Linguagem: Inglês

10.1098/rspl.1800.0034

2053-9142

Thomas Andrew Knight,

Tree-ring climate responses

The author prefaces his paper by declaring that the cause of the ascent of the sap in trees appearing to him not to have been as yet satisfactorily accounted for, he resolved to enter on an experimental inquiry on the subject; and that having met with some facts of which he had found no mention in any author, he flattered himself an account of them might not be unacceptable to the Society. The first experiments were made with a view to determine whether the sap does actually, as has been thought by some, ascend along he bark. For this purpose, circular incisions were made round a number of young healthy trees, and the bark removed for the space of about half an inch, or more, of the whole circumference. This, it was found, by no means impeded the growth of the upper part of the tree; but, on the other hand, the part of the stem below the incision scarcely grew at all, and in time even seemed to wither. From the whole of this investigation it seems probable, that the current of sap which adds the annual layers of wood to the stem, so far from ascending, actually descends from the young branches and leaves through the bark. The branches and leaves which supply this fluid became hence the next objects of the inquiry.