262 MR MILNE ON THE MID-LOTHIAN AND EAST-LOTHIAN COAL-FIELDS. 



In the New Craighall workings, a mass of sandstone (marked in tlie pre- 

 ceding figure by letter G) occurs between F and H. It there goes by the name of 

 a " saddleback," and has been mined in several places. It has very much the 

 shape shewn in the above figure, which iS drawn to a scale of 10 fathoms to an 

 inch.* This mass of sandstone is full of oval-shaped concretions, some of which 

 exceed a stone in weight. They are extremely hard, and give fire with steel. 

 The colour of this sandstone and of these concretions is reddish. The greatest 

 depth or thickness of this sandstone-bed is about 10 fathoms ; the width of it at 

 its base about 120 fathoms. It runs in a direction nearly S. by E., and has 

 been traced for about two and a half miles, viz. from the fork of the Dalkeith and 

 Fisherrow Railway, through the west part of the village of Old Craighall to the 

 wall of Dalkeith park. The above figure shews a section of the saddleback, at 

 right angles to the course now indicated. 



It will be remarked, that the coal-rough and its roof are not affected by this 

 saddleback. On the other hand, aU the superincumbent measm*es including the 

 roof of the splint-coal (which is a red-sandstone about 8 fathoms thick) mantle 

 over it. I learn from Messrs Wilson and Telfer, the overseers of Sir John Hope 

 at New Craighall, that this splint-coal is only 7 or 8 inches thick at the top of 

 the saddleback, being therefore reduced to about one-seventh of its ordinary 

 tliickness; and their opinion is, that the strata immediately subjacent to the 

 splint-coal are also reduced in thickness. 



The peculiarity of the foregoing section is, that the sandstone mass shewn 

 in it, does not extend laterally beyond a certain distance. 



It also deserves to be particularly noticed, that these two coal-seams, as they 

 mantle over the sandstone, thin away to a very considerable extent. This is more 

 particularly the case with the coal-rough. It is generally 4 feet thick, but it 

 gradually thins away to a mere shell 9 or 10 inches thick, when it reaches the 

 upper part of the protuberance. 



Let it not, however, be imagined, that the coal-strata are entu*ely exempt 

 from those sudden variations in thickness, which more frequently characterize the 

 other strata. One of the seams belonging to the upper series of coals, is known 

 by the name of the Diamond Seam. It was worked formerly at various places 

 in the parish of Newton. It is known to exist in the trough of the basin, and on 

 the east side of the Esk valley ; but it does not exist to the north or north-west 

 of Millerhill ; at or near that place, the coal thins away and entirely disappears, — 

 the roof and pavement meeting. 



This coal-seam, even where it exists and was worked, exhibited very anoma- 

 lous variations in its thickness and component parts. At Sheriffhall, it was de- 

 scribed to me as occurring in " balls" or nodular masses ; — so that when in 

 one place the seam was 2 or 8 feet thick, at another place, not a yard distant, 



* This was the case in the figure shewn to the Society. The above wood-cut is on a reduced scale. . 



