MR MILNE OX THE MID-LOTHIAN AND EAST-LOTHIAN COAL-FIELDS. 257 



ridge, sinks again into the valley of the T3Tie, and thereafter rises and crops out 

 entirely towards the east. We thus see, that this one stratum or deposit of coal 

 stretches through or covers a space whose horizontal surface measures in one di- 

 rection (viz. from NW. to SE.) ten or twelve miles. As to the distance to which 

 this particular coal-seam extends towards the north, no information can of course 

 be obtained, for it is there covered by the sea ; — towards the south, it is sup- 

 posed to reach even to the base of the Lammermuir range near Carlips and La 

 Mancha — a distance from Musselburgh of about eighteen mUes.* 



It may probably be asked, how is it known that it is one and the same seam 

 which is wrought at all these different places ? There is no difficvdty in proving 

 this to any one who has attended to the subject. In the first place, the thick- 

 ness of the seam at most of these points is the same. In the second place, 

 tlie roof and the pavement of the seam are almost every where the same, and 

 not merely the roof and pavement, but also the strata adjoining the roof and 

 pavement. In the third place, by laying down on a map, the outcrop of the 

 seam at any knoAvn point (as, for instance, Joppa), and drawing a line in the 

 dh'ection in which it is there seen to ran, that line will run thi-ough or very 

 nearly through all the places above mentioned, situated on the west side of 

 the basin ; and where this line is not exactly coincident with the actual out- 

 crop, the deviation can be accoimted for by special causes. In like manner, 

 by observing the direction in wliich the seam dijts, we see that it sinks to- 

 wards that very part of the basin, from which a similar coal-seam rises on the 

 opposite side. 



I may mention a second example, to prove the important fact now ad- 

 verted to. There is another coal in the series, which is equally remarkable, 

 as the " Great Seam" — not for thickness, but for certain no less valuable 

 properties. It is called the " North Greens" Coal. It is from this stratum that 

 the largest supplies of Parrot coal (so much used for the manufacture of gas) 

 are obtained. It occupies a very low place in the basin, being, generally speak- 

 ing, 250 or 300 fathoms beneath the great seam. It also can be recognised at a 

 multitude of different and distant places, though not so many as the Great Seam ; 

 for, being in the lowest part of the basin, it is not every where so easily reached. 

 But the fact of its being in this position, affords one test for its identification, 

 which does not exist in the other case. It lies immediately above a thick bed 

 of Umestone ; and as there are very few limestone strata in the whole deposit, 

 it is on this account the more readUy identified. I might add as another test, 

 the quality of the coal, which is shared by few others, and by none to the same 



* The Great Seam has not yet been identified at the places last mentioned ; but, judging from the 

 direction of the strata, and the fact that several other coal-strata, that are not far distant from the 

 Great Seam in other parts, have been recognised at these places, I have no doubt it also exists there. 

 VOL. XIV. PART I. K k 



