221 



and Sheffield, every square yard of whose streets requires 

 paving to prevent evaporation, together with their inferior- 

 lighted and low situated dwellings, are sufficient causes to 

 produce the additional 1,212 deaths from pneumonia or 

 inflammation of the lungs. 



4. Another superiority in Halifax and Huddersfield and 

 Wakefield, over Leeds and Sheffield, is in the Geological 

 nature of the soil and subsoil; the one being open and porous, 

 and which, according to the experiments of Schiibler, has 

 the power to hold or contain only 25 per cent, of water, while 

 that of stiff clay or brick earth will hold 6 1 per cent. ; or 

 every cubic foot of the former will hold only 27.3 lbs. of 

 water, and the latter 48.3 lbs., or nearly double the quantity ; 

 consequently, there will be double the evaporation of mois- 

 ture in the latter towns over that in the two former. Now 

 in a moist state of the air the changes are not fully effected 

 on the blood by respiration — its watery portions are not 

 carried off so freely from the exhaling surfaces — its purity 

 is diminished, thereby rendering the powers of life more 

 languid, and the system more open to the invasion of the 

 exciting causes of disease in general. 



Dr. Emerson, speaking of the mortality of Philadelphia, 

 says, " Great as was the amount of sickness, it was confined 

 almost entirely to the comparatively small proportion of 

 population inhabiting the unpaved or ill-paved environs. Our 

 observations led us to ascribe this exemption, for the most 

 part, to the pavement, which, by effecting a perfect draining, 

 prevents exhalation, at the same time that it admits of the 

 total removal of animal and vegetable matters. The chief 

 motive for paving the streets and side walks is usually con- 

 venience, but it has always appeared to us that by far the 

 most important object achieved by it was the preservation of 

 health." 



5. There is, no doubt, a close connexion between the qual- 

 ities of water and the Geological character of its locality. 



