from the Coal Measures of Torhane-hill. 37 
in what direction the sections are taken ; whether cut verti- 
cally, horizontally, or obliquely, there is no perceptible 
difference in the structure, and I say it without fear of con- 
tradiction, that no one, however skilled in microscopical 
observation could, from the inspection of a single specimen, 
state the direction in which the section had been made. Such 
is not the case with coal, as will hereafter be shown ; a single 
inspection is sufficient to enable a practised microscopist to 
determine the actual direction of the section, whether trans- 
verse or longitudinal. 
Examination of portions of the Mineral having Plants 
imbedded in their substance. — I have already stated that 
plants and the impressions of plants are not uncommon in this 
mineral ; of these I have made numerous sections and chip- 
pings, and most instructive they all are. The plants appear to 
be principally Stigmarice, and exhibit more or less of the three 
tissues known to botanists as the cellular, the woody, and the 
vascular ; and should one or more of these be present in any 
section, the minutest fragment even of a cell or vessel can be 
readily recognised by a practised observer ; they, as it were, 
stand out boldly from the mineral matter in which they are 
imbedded, and (as shown in figs. 3 and 4) can be distinguished 
in all cases by their rich brown colour ; but such plants I not 
only consider as extraneous and not forming the bulk of the 
mineral, but such plants my investigations lead me to conclude 
rarely if ever form coal ; at all events no coal that I have yet 
examined has ever exhibited the least trace of being made up 
of such plants as are so commonly seen imbedded in this 
mineral. Even the coal lying upon this mineral, and running 
through it in every possible direction, is composed principally 
of woody tissue, and not of plants such as these. 
Examination of sections of the Mineral having Coal in juxta- 
position. — The first specimen of this kind which I had the 
opportunity of examining was brought by Mr. Bowerbank 
himself from one of the Torbane-hill pits. From this speci- 
men several sections were taken ; one of them slightly mag- 
nified, is represented in Plate V., fig. 1. I regret I cannot 
show you the specimen itself, it being lodged in the Court of 
Session, in Edinburgh ; but I have been favoured with a some- 
what similar one through the kindness of Mr. Gratton. As the 
block lay in the pit, the coal was situated below the mineral 
in the position I now hold it, and you will readily be able to 
distinguish the one from the other by the naked eye ; but 
when viewed with a power of at least 50 diameters (as 
shown in Plate III., fig. 5), the smallest fragment of the coal 
that may happen to be mixed up with the mineral may be 
