Observed by Hooke

These pores were so exceeding small and thick, that in a line of them, 1/12th part of an Inch long, I found by numbring them no less then 150 small pores; and therefore in a line of them an Inch long, must be no less then 2700 pores, and in a circular area of an Inch diameter, must be about 5725350 of the like pores; so that a Stick of an Inch Diameter, may containe no less then seven hundred and twenty five thousand,[725000] besides 5 Millions of pores, which would, I doubt not, seem even incredible, were not every one left to believe his own eyes.

as I shall elsewhere endeavour to manifest when I come to show the use of the Air in respiration, and for the preservation of the life, nay, for the conservation and restauration of the health and natural constitution of mankind as well as all other aereal animals, as also the uses of this principle or propriety of the Air in chymical, mechanical, and other operations.
CHARCOAL, or a Vegetable burnt black........ if a better Microscope be made use of, there will appear an infinite company of exceedingly small, and very regular pores, so thick and so orderly set, and so close to one another, that they leave very little room or space between them to be fill'd with a solid body, for the apparent interstitia, or separating sides of these pores seem so thin in some places, that the texture of a Honey-comb cannot be more porous.......
These pores were so exceeding small and thick, that in a line of them, 1/12th part of an Inch long, I found by numbring them no less then 150 small pores; and therefore in a line of them an Inch long, must be no less then 2700 pores, and in a circular area of an Inch diameter, must be about 5725350 of the like pores...

That as there is one part that is dissoluble by the Air, so are there other parts with which the parts of the Air mixing and uniting, do make a Coagulum, or precipitation, as one may call it, which causes it to be separated from the Air, but this precipitate is so light, and in so small and rarify'd or porous clusters, that it is very volatil, and is easily carry'd up by the motion of the Air, though afterwards, when the heat and agitation that kept it rarify'd ceases, it easily condenses, and commixt with other indissoluble parts, it sticks and adheres to the next bodies it meets withall; and this is a certain Salt that may be extracted out of Soot.

... But that which I chiefly took notice of, was, that cutting off a small piece of it [wood], about the bigness of my Thumb, and charring it in a Crucible with Sand, after the manner I above prescrib'd, I found it infinitely to abound with the smaller sort of pores, so extreamly thick, and so regularly perforating the substance of it long-ways, that breaking it off a-cross, I found it to look very like an Honey-comb;
Micrographia Observation XVI