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XL. Upon the different Qualities of the Aihurnum of Spring- 

 and Winter-felled Oak Trees. By Thomas Andrew Knight, 

 Esq. F.R.S.* 



A H E timber of oak trees felled in winter was formerly very 

 generally believed to be much superior in quality to that afforded 

 by similar trees felled in spring; and the same opinion appears 

 to be still rather extensively entertained ; though the practice of 

 felling in winter has wholly ceased, on account of the increased 

 value of the bark. But efforts have been made, and supposed 

 to have been successful, to obtain the advantages of both seasons 

 of felling, by taking off the bark in spring, and suffering the tree 

 to stand till the ensuing winter. A good many facts which had 

 come within my own observation, and information which I re- 

 ceived from other sources, had satisfied me that the durability of 

 the alburnum, at least, of oak trees is considerably increased by 

 this mode of management ; and I was, consequently, led to make 

 a few experiments (with the result of which I now take the li- 

 berty to trouble the Royal Society) with the hope of discovering 

 the cause of this supposed superiority in the quality of the wood 

 of winter-felled trees. 



In the spring of 1817, two oak trees, of nearly the same age, 

 and growing contiguously in the same soil, were selected, each 

 being somewhat less than a century old. The one was deprived 

 of its bark, to as great an extent as the inexperience of my work- 

 men permitted me to have done without danger to the tree, and it 

 was then suffered to remain standing. The other tree was felled, 

 and, in the usual manner, immediately stript of its bark ; and 

 the trunk was then removed to a situation in which it was se- 

 curely protected from the sun and rain. The following winter, in 

 December, the first tree (which still retained life) was felled, and 

 its trunk immediately placed in the same situation with that of 

 the other tree ; pieces of each, selected from similar parts, have 

 been subjected to the following experiments at different subse- 

 quent periods. 



Small blocks, of similar form and size, were taken from the 

 alburnum of each tree ; and after these had ceased to lose weight, 

 in a very warm and dry situation, the specific gravity of each was 

 ascertained ; when that of the alburnum of the spring-felled tree 

 was found to be 0*606, and that of the same substance of the 

 winter-felled tree to be 0*5G5, taking the average of several pieces 

 of each. 1 had anticipated a loss of weight to about this amount 

 in tlic alburnum of the winter-felled tree, having inferred, from 

 former experiments, that it must have given out a large quantity 



• From the Trnnsactions of the Royal Society for 1820. I'art II. 



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