114 DR. REDFERN, ON THE TORBANEHILL 



block of coal. To ensure accuracy, I made sections in three 

 places, at different depths, in half an inch of cemenl-stone at 

 the top ; and others in the coal, at distances of 2, 4, 6, 10, and 

 16 inches from the top of the seam. The results were pre- 

 cisely similar to those which I obtained from sections prepared 

 from numerous other blocks of the coal obtained from a great 

 variety of sources. At each part of a bed of coal examined 

 I have made at least three thin sections, and distinguished 

 these from each other by the letters H. S., for horizontal sec- 

 tions ; V. S. a., for vertical sections taken from the side of a 

 small block ; and V. S. b., for vertical sections cut from the 

 ends of such blocks. Having bestowed the greatest care in 

 the investigation, from beginning to end, I feel assured that 

 other observers will corroborate my facts and the correctness 

 of my drawings, from which the accompanying plates have 

 been executed, however different their conclusions may be 

 from my own. 



Horizontal sections taken from all parts of the Torbanehill 

 coal, except about the upper two inches, show : — 



1st. A number of irregularly rounded spots of a lemon- 

 yellow colour, varying in diameter from about l-250th to 

 1 -800th of an inch, and bounded by dark- brown matter, which 

 separates them from each other (Plate VII., fig. 3), or from, 

 2nd, smaller yellow patches, of a distincdy angular and poly- 

 gonal shape, having a very uniform diameter of 1-1 500th of 

 an inch, and a dark-brown outline, which in many places is 

 distinctly double. 



Vertical sections show these yellow spots elongated, mea- 

 suring about l-300th to l-1200th of an inch horizontally, or 

 in the direction of the lamina? of bedding, and from l-500th 

 to 1-1 900th of an inch perpendicularly to these laminae and 

 the whole bed (Plate VII., fig. 4). In whatever direction a ver- 

 tical section is made, the appearances which it presents are 

 the same. In everyone there is a general horizontal striation ; 

 i. e., having its stria? parallel to the laminae of bedding. In 

 horizontal sections there is no striation whatever. 



Here are two points of such primary importance in the in- 

 cjuiry into the real nature of the Torbanehill and other coals, 

 that I cannot do them sufficient justice without a slight 

 digression from the preceding account of the appearances of 

 sections. 



I have before stated that a small block of coal with six 

 surfaces presents two appearances when examined as an 

 opaque object : one on its upper and lower surfaces, and the 

 other on its sides and ends. One appearance is that of a 

 numl)er of rounded yellow spots in a black mass ; the other, 



