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districts of Doncaster and Thorne, 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 

 exceedingly healthy is, that they rest upon the millstone 

 grit, which, as we shall see in the sequel, presents conditions 

 highly favourable to longevity. 



Leeds and Sheffield, both manufacturing towns of different 

 staple commodities, the one of flax and woollens, 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 unhealthiness for the same three years exactly 

 alike, viz., 2.7 per cent per annum, or I in every 38 persons 

 dying. These two towns are, however, exceedingly un- 

 healthy; and supposing their population to be equal to 

 that of Huddersfield and Halifax, in every ten years 17,430 

 persons more, in proportion, would be destroyed by disease. 

 The reason why the rates of mortality are alike in Leeds 

 and Sheffield is, because they are built upon exactly the same 

 strata, which are continuous from one place to the other; 

 and why they are so extremely unhealthy is, because they 

 are located upon " clays and binds" of the coal formation, 

 which present certain conditions prejudicial to health. 



The districts of Wakefield and Barnsley, in like manner, 

 have degrees of healthiness or rates of mortality exactly 

 alike, these being intermediate between those of Huddersfield 

 and Halifax, and of Leeds and Sheffield. The towns of 

 Wakefield and Barnsley are built upon the same rock of the 

 coal strata, and which affbrds sanatory advantages differing 

 from the before-named districts. 



That the healthiness of any town depends directly or 

 indirectly (cceteris paribus) upon its Geological site, is plain, 

 since all the conditions necessary to health, as ventilation, 

 drainage, the supply of water, pure air, &c., are dependant 



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