10 
phical Transactions of Manchester. It would, indeed, be 
very presumptuous in me to propose any line for the Man- 
chester Society, and I perfectly agree with the observation 
of Mr. Hartop, that it would be wrong for us to prescribe 
any line for the Lancashire Society, but that they should 
select their own line, without reference to what should be done 
on our side, and that the two lines might be united by parti- 
cular observations. Nevertheless, I must give it as an 
opinion, that the lines of section in that Coal Field which 
Elias Hall has published, are the very best which can be 
adopted. They are all at right angles with the minerals, 
and if it were possible for their Society to correct these 
sections, they would contain every thing which it is possible 
or requisite to know of that country. They would enable 
them to compare the changes which occur in their minerals 
in their passage from north to south, and to ascertain how 
far the law* of developement or maximum thickness on the one 
direction, and a corresponding decrease on the opposite, cor- 
responds with that which seems to obtain in the Yorkshire 
Coal Field. And Hall's sections of the northern side, if 
corrected, would also be of immense value to us, and enable 
us to solve some of the difficulties connected with the strata 
on the north of the Calder between Halifax and Aberford ; 
we should learn whether there is not a general decrease in 
the thickness of coal beds in their passage to the east, and 
thus obtain a knowledge of the true form of these strata, 
which would lead to such generalizations in the mode of the 
distribution of coal, as would be of great service to inductive 
geology. 
With regard to the proposed line of section through part 
of our Coal Field, it may be said, — 1st, that the whole coun- 
try on this side of the Derbyshire axis at Mottram to Salters- 
brooke, a distance of ten or twelve miles, is of the most 
uninteresting description (speaking geologically.) Four 
* A law pointed out by me on a former occasion. 
