REV. W. THORP, B. A.— AGRICULTURAL GEOLOGY, ETC. 231 
of water either increased or decreased mortality to a considerable 
extent ; the doctor instanced a village near Halifax where the water 
was bad, and the inhabitants were never free from disease. Mr. Clay 
considered there was most typhus on the brow of hills looking south, 
and supported Dr. luglis and Mr. Briggs with respect to the quality 
of the water. The Rev. Mr. Thorp said that if the rates of mortality 
from the fifth report of the Registrar General were examined, there 
would be found very gxeat variations according to locality, such as 
neither density of population nor droughts could account for, and 
this paper sought to establish a connection between the degTee of 
salubrity of any place and its geological site. 
These data are interesting for comparison at the present time, 
they preceded the passing of the Corporation Acts, and indicate the 
state of the towns in draining and other matters. The application 
of systems of drainage, extensive water supplies carried long distances 
from favourable situations, and general attention to cleanliness has to 
a great extent rendered the death-rate independent of the geological 
formation on which the town may chance to be built, and to-day 
there is little difference in the average mortality of the large towns. 
At a meeting of the Society held at York in July, 1846, Earl 
Fitzwilliam in the chair, the honorary secretary, the Rev. W. Thorp, 
contributed a paper entitled Illustrations of the Geology of the 
Yorkshire Coal-field. He observed that this coal-field, whilst being- 
one of the largest, has hitherto been less exhausted of its minerals 
than any other in Great Britain. The towns of Sheftield, Leeds, 
Barnsley, Bradford, Halifax and Huddersfield owe their existence to 
this coal-field. About four million tons of coal are annually raised, 
and owing to the want of cheap and quick communication to the sea, 
nearly all this coal is consumed in the district, in this respect difi'ering 
largely from Xorthumberland and Durham, which annually export 
about seven million tons. Some of the lower portions of the strata 
of this coal-field are prolonged into Derbyshire, and others into 
Lancashire. The vertical thickness of the whole strata he calculated 
to be about 1200 yards, which may be divided into three parts : — 
The lowest, about 200 yards in thickness, does not produce coal of 
any gTeat value ; the middle portion, prolonged into Derbyshire, is 
