And indeed, all that I have yet seen, seem to have been rotten Wood before the petrifaction was begun; and not long since, examining and viewing a huge great Oak, that seem’d with meer age to be rotten as it stood, I was very much confirm’d in this opinion; for I found, that the grain, colour, and shape of the Wood, was exactly like this petrify’d substance; and with a Microscope, I found, that all those Microscopical pores, which in sappy or firm and sound Wood are fill’d with the natural or innate juices of those Vegetables, in this they were all empty, like those of Vegetables charr’d; but with this difference, that they seem’d much larger then I have seen any in Char-coals; nay, even then those of Coals made of great blocks of Timber, which are commonly call’d Old-coals.

The reason of which difference may probably be, that the charring of Vegetables, being an operation quickly perform’d, and whilest the Wood is sappy, the more solid parts may more easily shrink together, and contract the pores or interstitia between them, then in the rotten Wood, where that natural juice seems onely to be wash’d away by adventitious or unnatural moisture; and so though the natural juice be wasted from between the firm parts, yet those parts are kept asunder by the adventitious moystures, and so by degrees settled in those postures.

And this I likewise found in the petrify’d Wood, that the pores were somewat bigger then those of Charcoal, each pore being neer upon half as bigg again, but they did not bear that disproportion which is exprest in the tenth Scheme, between the small specks or pores in the first Figure (which representeth the pores of Coal or Wood charr’d) and the black spots of the second Figure (which represent the like Microscopical pores in the petrify’d Wood) for these last were drawn by a Microscope that magnify’d the object above six times more in Diameter then the Microscope by which those pores of Coal were observ’d.

Now, though they were a little bigger, yet did they keep the exact figure and order of the pores of Coals and of rotten Wood, which last also were much of the same cize.

The other Observations on this petrify’d substance, that a while since, by the appointment of the Royal Society, I made, and presented to them an account of, were these that follow, which had the honour done them by the most accomplish’d Mr. Evelin, my highly honoured friend, to be inserted and published among those excellent Observations wherewith his Sylva is replenish’d, and would therefore have been here omitted, had not the Figure of them, as they appear’d through the Microscope been before that engraven.

This Petrify’d substance resembled Wood, in that

First, all the parts of it seem’d not at all dislocated, or alter’d from their natural Position, whil’st they were Wood, but the whole piece retain’d the exact shape of Wood, having many of the conspicuous pores of wood still remaining pores, and shewing a manifest difference visible enough between the grain of the Wood and that of the bark, especially when any side of it was cut smooth and polite; for then it appear’d to have a very lovely grain, like that of some curious close Wood.