( ) 
VI. The ExtraSi of another Letter from Mr. An- 
thony Van Leuwenhock, to the Royal So- 
ciety ; Concerning the difference of Timber 
gromng in different Countries , and felled at 
different Seafons of the Tear. 
I, A S to the difTerence of Timber felled in Winter 
l\ from that felled in the Summer, the common 
Opinion is, that the former is the ftronger, and more la- 
iling, as being more clofe and firm ; but his own Senti- 
ment is, that there is no difference, except in the Bark 
and outermoft Ring of the Wood, which in the Summer 
are fofter, and fo more eafily pierced by the Worm. 
Wood confiding of hollow Pipes, which in Summer and 
Winter both are full of Moifture, they do not Ihrink 
in the Winter, and therefore the Wood cannot be clofer 
at one time than another, for other wife it would be full 
of cracks and clefts. The fudden and unexpefled Rot- 
ting of fome Timber, he conceives to proceed from 
fome inward decay in the Tree before it was felled, ha- 
ving obferved all Trees to begin to decay at firft in the 
midft or Heart of the Tree, though pofTibly the Tree 
may ftand and grow for near an Hundred Years after- 
wards, and increale in bignefi all along, 
z. He fays, he was once of Opinion, That Trees 
growing in good Ground, but increafing flowly, w^ere 
the beft and ftrongeft Timber; and that thofe Trees 
which in few Years grew large, was the fofteft and brit- 
tkft; the contrary to which upon Enquiry of Experi- 
eaced Workmen he found to be true, and inftances in an 
Elm of Eighty Years growth, which was Eleven Foot in 
Circumference, and proved excellent tough Timber. 
J. The 
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