﻿306 . Royal Society : — 



We very much question whether in practical teaching the new form 

 has any advantage over the old. In an appendix Mr. McColl pro- 

 poses a uniform method of resolving algebraical expressions into 

 factors which can frequently be employed with advantage. On the 

 whole this is a book from which any one engaged in teaching algebra 

 may get useful hints, though we do not suppose it will displace any 

 of the many excellent elementary works on Algebra at present in 

 common use. 



XLII. Proceedings of Learned Societies, 



ROYAL SOCIETY. 



[Continued from p. 241.] 



Dec. 22, 1870.— General Sir Edward Sabine, K.C.B., President, in. 



the Chair. 



fPHE following communications were read: — 

 -*- " On the Extension of the Coal-fields beneath the Newer For- 

 mations of England ; and the Succession of Physical Changes whereby 

 the Coal-measures have been reduced to their present dimensions." 

 By Edward Hull, M.A., F.R.S., F.G.S., Director of the Geological 

 Survey of Ireland. 



In this paper the author, embodying with his own the observa- 

 tions of previous writers on the physical geology of Great Britain, 

 especially those of Murchison, Godwin- Austen, Ramsay, Phillips, 

 and the late Professor Jukes, showed that the Coal-measures were 

 originally distributed over large tracts of England, to the north and 

 to the south of a central ridge or barrier of Old Silurian and Cambrian 

 rocks, which stretched across the country from North Wales and 

 Shropshire into the Eastern Counties, skirting the southern margin 

 of the South Staffordshire Coal-field. This barrier, or ridge, was a 

 land-surface till the close of the Carboniferous period. 



To the north of the central barrier, the highlands of Wales, the 

 mountains of the Lake- district, and probably small tracts of the south- 

 ern uplands of Scotland formed land-surfaces skirting portions of 

 the Carboniferous area, while the Carboniferous tract to the south of 

 the central barrier was probably bounded by a land-surface trending 

 along the southern coast of England. The distribution of the Coal- 

 measures at the close of the Carboniferous period was illustrated by 

 a Map, No. 1 . 



It was then shown that the whole Carboniferous area was sub- 

 jected to disturbances through the agency of lateral forces, whereby 

 the strata were thrown into folds along axes ranging (approximately) 

 in east and west directions ; and as denudation accompanied and 

 followed these disturbances, and acted chiefly over the arches (or an- 

 ticlinals), large tracts were divested of Upper Carboniferous strata, 

 and thus the first phase in the marking out of the limits of our pre- 

 sent coal-fields was brought about. The effects of these movements 

 and denudations were illustrated by Map No. 2. 



The disturbances which ensued after the deposition of the Permian 



