396 Proceedings of the Royal Society. 



more than ten or twelve, being those which appertain to the lower 

 part of the deposit. The vertical depth of the Esk basin in its 

 trougli, — or, in other words, the thickness of the deposits composing 

 it, is between 1000 and 1050 fathoms ; but this thickness diminishes 

 rapidly to the south, arising chiefly from the coal-seams and sand- 

 stone strata thinning away in that direction ; and which diminution 

 is compensated in but a trifling degree, by the increased thickness 

 of the limestone in the same direction. 



The Tyne basin comprehends only the deposits lying below the 

 Great Seam of coal, and the entire thickness of these, is greatly less 

 than in the Esk basin, arising chiefly from the sandstones and coals 

 thinning away towards the east. 



The strata on the west side of the Esk basin, dip to the east and 

 south-east at a very steep angle, and are in some places absolutely 

 vertical. On the opposite or east side of the Esk basin, they 

 slope to the west at an angle varying from 20° to 40°. 



The strata on the west side of the Tyne basin dip to the east, at 

 an angle varying from 15° to 20° ; and on the opposite or east side 

 of the same basin, they dip to the west at an angle of only 5° or 6°. 



In the intervening ridge which runs from Prestonpans to the 

 Roman Camp, the strata mantle over from the one basin into the 

 other, and are there occasionally broken so as to shew an anti- 

 clinal line. 



The different kinds of coal were described ; and it was stated, 

 that each kind was characterized by differences in the fissures or 

 joints intersecting them. 



The principal slips in the district were next pointed out ; and 

 the author referred to a table he had constructed, shewing the di- 

 rection of each, and the amount of dislocation produced on the in- 

 tersected strata. Between eighty and ninety of these were also 

 laid down on the map accompanying the memoir. 



In describing the unstratified rocks of the district, the author 

 mentioned, there were no hills or amorphous masses of trap within 

 the proper limits of the Lothian coal-field ; and that the trap shewed 

 itself only in dykes, which run in straight lines intersecting the 

 strata. He pointed out three or four such dykes, varying from 60 

 to 120 feet in width, — all of which appeared gradually to thicken 

 towards the west, and all of which run in nearly an east and west 

 direction. 



March 5. — Sir T. M. Brisbane, Bart. P. in the Chair. 

 The following Honorary Fellows were elected : 



Prof. Tiedemann, Heidelberg. Prof. Miiller, Gottingen. 

 The following Communications were made : 



1. Notice regarding a New British Species of Coregonus. 



By Dr Parnell. 



2. Abstract of Part II. of Memoir descriptive and explana- 



tory of the Mid-Lothian and East Lothian Coal-fields. 



