MINERAL PRODUCTS. 
174 
attempts to discover them. The opinions of working colliers on this 
point have too often been preferred to the legitimate deductions of 
science, and even yet persons will perhaps be found willing to credit the 
delusive tale of finding good coal by going deeper. But the warning 
must be given, though it be disregarded; and from all the natural 
exhibitions on the coast, as well as from the result of every experiment 
inland, I am compelled to state, that any hope of discovering seams of 
coal more than eighteen inches or two feet in thickness, in any part of 
the strata above the upper lias or alum shale, is entirely unsupported by 
reason and experience. That the coal measures of Durham and western 
Yorkshire exist (covered by magnesian limestone and red sandstone) 
beneath the lias, is probable, but the practicability of reaching them by 
pits, even in Cleveland, or near York, is very questionable, and the 
expense of the experiment may be ruinous. 
Of several thin and variable seams of coal which appear among the 
sandstone rocks above the lias, only the lower one immediately above the 
dogger, and the upper one not far beneath the gray limestone, have been 
found worth the expense of working. The upper seam is the most 
regular, and has been worked at Clough ton Wyke, Maybecks, Goadland, 
Glaizedale, Danby, Shunnor Hoe, Blakelioe, Rudland, Coxwold, Yew- 
borough Park, Colton, &c. : that this and the lower seam may be opened 
in new places, is highly probable, and such attempts may be productive 
of much local advantage, but they should be guided by geological induc- 
tion, and not abandoned to ignorance and empiricism. 
The manufacture of alum from the upper lias shale, has furnished 
extensive employment and considerable emolument, but there appears 
little encouragement to establish works in new situations. The principal 
material in the process does not retain its essential characters much 
further south than the present establishments ; and the difficulty of 
transporting materials to a distance will probably confine the trade to 
the vicinity of the Peak, Lyth, Kettleness, Boulby, Rock cliff, and 
Guisborough. 
