20^ 



upon the same cause. Thus, indirectly, where good building- 

 stone exists, the walls of houses are seldom made less than 

 fifteen inches thick ; and when thick walls are made, the 

 rooms of the houses are made larger also, and are placed, 

 if possible, in streets; and hence a better ventilation, more 

 light, air, &c. A town built upon a rock possesses also a 

 natural good drainage, arising from fissures and porosity of 

 the substratum; there is also less of exhalation and of 

 miasmata, and, therefore, a purer air. The water in such 

 cases is generally not only purer but more plentiful. The 

 millstone grit and mountain limestone regions, and of other 

 coarse sandstones and of the oolites, are the most healthy 

 districts ; while those of clay are the most unhealthy ; and 

 here are seen small inferior houses — no attention to the size 

 of rooms, houses, or streets, imperfect sewerage, malaria, 

 and all its effects. The new red sandstone and magnesian 

 limestone hold an intermediate station between the two, the 

 former having a very imperfect, and in many places no 

 building material except the marl seams; yet the new red 

 sandstone has good natural drainage, while the limestone 

 makes inferior houses, and the water upon it is scanty and 

 not very pure. Thus Bradford, with a dense population, is 

 more healthy than Leeds, having a rate of mortality of 1 in 

 43 dying annually, while in Leeds 1 in 38 die; and this 

 because one-half of Bradford is built upon the flagstone rock, 

 forty-five yards thick. Newcastle-upon-Tyne stands upon 

 the clays of the coal measures, and has a rate of mortality 

 higher than Leeds, viz., 1 in 34 ; but the millstone grit and 

 mountain limestone districts of Glendale, Bellingham, and 

 Haltwhistle, about fifteen miles west of Newcastle, are just 

 twice as healthy as Newcastle, their rates being 1 in 68. 



Hull, standing upon clay, and built of bricks made from 

 it, has a rate so high as 1 in 34, being the same as Newcastle. 

 Cambridge, for the same reason, is as high as 1 in 37* 



i 



