REV. W. THORP, B.A. — AGRICULTURAL GEOLOGY, ETC. 229 
only is the diagram an epitomised series of sections in one line in any 
direction but it also forms a sort of ground plan of the wliole of the 
area of the Coal-field, and shows the relative position of the pits and 
sections superficially, at the same time that the relative position and 
thickness of the strata vertically are exliibited. 
At the meeting held on December 18th, 1844, the newly elected 
secretary, the Rev. W. Thorp, read a paper on the causes of the differ- 
ent rates of mortality in some of the most populous towns in the West 
Riding of Yorkshire. In this paper the author endeavours to show that 
the character of the strata on which towns are erected exercises a gTcat 
influence on the health of the inhabitants. " Halifax and Huddersfield, 
both large manufacturing towns of the same staple article, and with 
a dense population of above 100,000 persons in each, (i.e., in the 
Registrar General's districts), have exactly the same rates of mortality. 
That is, taking the population and the number of deaths in each 
district, and dividing the one by the other, the rate of mortality in 
each is 2.1 per cent, per annum, or 1 in 48 dying for the three years 
past, or as far as we have any authentic information from registration. 
These towns moreover are extremely healthy, being more so than any 
of the large towns in England, with the exception of Kidderminster. 
They are even more healthy than the rural districts of Thorne and 
Doncaster, and of Selby, Goole and Pontefract. The cause why 
Halifax and Huddersfield possess similar degrees of healthiness is, 
that they are built upon the same geological strata ; and why they 
are so healthy is, that they rest upon the millstone grit," which secures 
good natural drainage, forms good building stone, of w^hich houses 
are erected with walls 15 inches thick, and proportionably large rooms. 
The water is purer and more plentiful, and there is less of exhalation 
and miasmata, and therefore a purer air. " Leeds and Sheffield, both 
manufacturing towns of different staple commodities, the one of flax 
and woollens, and the other of steel and iron ; the one containing 
twice the amount of population to the other have likewise their rates 
of mortality or degrees of unliealthiness for the same three years 
exactly alike, viz., 2.7 per cent, per annum, or 1 in every 38 persons 
dying. These two towns are, however, exceedingly unhealthy, and 
supposing their population to be equal to that of Huddersfield and 
