25 
MR. SOPWITH's ISOMETRICAL PROJECTION OF THE MINING 
DISTRICT OF ALSTON-MOOR 
Was exhibited ; and, being called upon by the Chairman, 
Mr. Sopwith gave the following explanation : — 
He observed, that the general subject of plans and sections 
of mines and mineral districts was one of great importance 
to the community, and especially deserving the notice of 
Societies like the present. The presentation of such plans 
is requisite,in order to preserve a knowledge of what has 
been done in subterranean works ; and, with this object in 
view, it is important that such representations should be as 
clear and explanatory as the circumstances will admit of. 
The usual dra^vings employed in connexion with mining, are 
what are well known by the name of Ground Plans and Sec- 
tions ; the one representing all horizontal objects, the other 
all vertical objects. Every object, therefore, which departs 
from a parallelism with these planes, must be, to a greater 
or less extent distorted ; and this imperfection is common to 
all plans or drawings which are confined to the representa- 
tion of one plane only. This description of plan and sec- 
tion, however, from its great simplicit}^ and universal adop- 
tion, is that on which we must be chiefly dependent for per- 
petuating a knowledge of mining operations. Mr. S. stated 
that Grovemment had established an office in connexion 
with the Museum of Economic Geology, for the purpose of 
preserving mining records. Draftsmen would then be em- 
ployed to copy, on an uniform scale, all such plans and sec- 
tions as may be deemed of sufficient interest to be thus pre- 
served ; and, by this means, he trusted that a body of in- 
formation would be collected which would prove of the ut- 
most value in carrying on the future operations of this and 
of all other mining districts. With respect to the want of 
accurate maps, Mr. S. trusted that some important data 
might be obtained from the Board of Ordnance, whose rough 
D 
