198 Miscellanies. 
_ vailing opinion, the writer of that article believes that timber is most du- 
rable when obtained from trees cut during summer. I am not prepared 
to call in question the correctness of his belief ; but on the contrary, I 
am able to say, that as far as my observations have been extended, they 
have proved corroborative of it. ‘There are some points, however, af- 
fecting his theory, which, I think, require further consideration. * 
Agreeably to his view, the sap of vegetables is confined to the al- 
burnum during summer, but on the approach of frost, it retreats to the 
heart-wood, where it remains during winter. And thus, he supposes, 
the fluids of the tree continue to circulate between the heart-wood and 
alburnum year after year while the tree lives. As the writer speaks 
of the “exact thickness of the alburnum,” I presume he means by the 
term alburnum, ald the white-wood, or all those concentric layers which 
lie exterior to the colored central portion of the trunk ; and from which 
they are separated by a well defined circle. If this presumption be 
true, it appears to me that grave objections rest against his theory. 
The summer and winter reservoirs, which he appropriates to the sap, 
are not always of equal capacity ; indeed, they are very rarely, if ever, 
precisely so. Some trees between one and two feet in diameter, have, 
as I find by calculation, thirty eight times more alburnum than colored 
wood. Others, of smaller dimensions, on a transverse section of the 
trunk, show a mere speck of heart-wood, capable of holding not more 
than a two hundredth part of the fluids of the alburnum. If a dedue- 
tion be made from the capacity ‘of the central wood, on account of su- 
ior density of structure, the difference will be still greater in the 
contents of the two reservoirs. The author of this theory, (perhaps I 
ought to say hypothesis,) must then either find an autumnal ore for 
the excess of moisture, or abandon his opinion 
Again, p! ogists tell us, without reserve, ‘that heart-wood consists 
are “dead and ies formed central layers.” If all vital action has 
ye in this | of the tree, it is not only unnatural to suppose 
oy ate se. eekcy 
lifeless hae 
ae. his ninth aabelas I was . with the sc tees extraordinary 
: “The results of these experiments accord with a known 
Bet ix in regard to the sugar maple, namely, that no sap can be obtained 
from the tubes of the alburnum of that tree, and therefore they ‘ are 
obliged to eid the hole for the tube through the alburnum, into the 
heart-wood before it will run.” The truth is, that if the bark be be re- 
the s laceration of 
copious flow of Pie 
