40 Structure of a peculiar Combustible Mineral^ 
merits be correct. I am fully aware that the prevalent opinion 
with geologists and botanists is, that coal is made up of fossilized 
vegetable matter, and that this vegetable matter may consist of 
stigmariae, ferns, mosses, &c. ; in short, of a great variety of 
vegetable substances. My investigations, however, lead me 
to believe that the basis of coal is essentially a peculiar kind 
of wood, and that when ferns, stigmariae, lepidodendra, and 
other plants occur in coal or its neighbourhood, they should 
be considered foreign to the coal, as these plants, before 
noticed, are to the Torbane-hill mineral. However contrary 
this may be to our preconceived notions, yet all the sections 
on the table before you, on a careful examination by an unpre- 
judiced observer, can lead to no other conclusion. I believe 
that there are in this room at the present time more sections 
of coal than any private individual has ever yet produced 
before a scientific assembly, and it is from these specimens, 
and from the study of these alone, that I am warranted in 
making this assertion. The botanist will remember that most 
of the plants generally considered as forming coal, are such 
as on section will exhibit more or less of the cellular, woody, 
and vascular tissue : now it is a remarkable fact, that most 
of the plants visible to the naked eye in the Torbane-hill 
mineral, as well as those lying in the strata above and below 
coal in general, are those which may contain spiral or other 
vessels ; but, judging from all the sections of coal now before 
you, as well as chippings of others too numerous to mention, 
I am forced to the conclusion that such plants rarely if ever 
form coal, the basis of coal being essentially wood^ of what 
kind, however, I will not at the present stage of the inquiry 
venture to mention, but I will state thus far, that it approaches 
more nearly to that of the Coniferae than any other wood ; 
because in the Coniferae, as we know them in this country, 
there are few if any vessels or ducts in the woody part 
of the trunk, but occasionally cellular tissue in what are called 
the turpentine vessels, the entire bulk being woody fibre. 
Such is the case in coal. In all the sections that I have 
examined of undoubted coal, I have as yet found no trace of 
a spiral vessel or a dotted duct, but in one or two instances 
where the woody structure has been very evident, as shown in 
Plate v., fig. 3, the fibres were evidently dotted. 
External Appearances of Coal. — ^These must be so well 
known to most of you, that I need not dwell further upon 
them than to particularise one or two kinds which approach 
nearest to the Torbane-hill mineral in general appearance. 
The most remarkable of these is from Methil, in Fifeshire, 
and known as the Brown Methil. So peculiar is it, that 
when scratched with a knife, the streak is brownish-black 
