10 INTRODUCTION. 



may be well to subjoin a few additional facts, derived from 

 the cholera-experience of 1848-9, which, from its general 

 diffusion, tested, in a very remarkable degree, the relative 

 healthfulness of different provincial towns, and of different 

 metropolitan districts. Thus, among the whole population of 

 the ten towns of Exeter, Derby, Cheltenham, Leicester, 

 Nottingham, Eochdale, Norwich, Preston, Halifax, and Bir- 

 mingham, amounting to 657,000, there were no more than 

 238 deaths from cholera ; whilst, in an equal population 

 inhabiting the towns of Newcastle-under-Lyne, Plymouth, 

 Brighton, Merthyr Tydvil, Portsea, Tynemouth, Wigan, Hull, 

 Wolverhampton, and Leeds, the number of deaths was no 

 fewer than 10,415, or forty-three times as great. So again, in 

 twenty-five Metropolitan districts, chiefly on the north side of 

 the Thames, having a total population of about 310,000, the 

 number of deaths from cholera was only 389 ; whilst in 

 twenty-two districts, almost entirely on the south side of the 

 river, the number of deaths, out of a population of almost 

 exactly the same amount, was 5,932, or more than twelve 

 times as great. In no instance is there the least difficulty in 

 accounting for these contrasts. They all point to the same 

 general conclusion; that, namely, of the immense influence 

 which is exercised over human health by the purity of the air 

 that is breathed, and of the water that is drunk ; and it is 

 because these two conditions are in a great degree capable of 

 public regulation, that legislative interference has so much in 

 its power, and is so imperatively called for by the interests of 

 humanity, which speak solemnly and distinctly to all who 

 claim the rights of property in the foul " plague-spots " which 

 deface our country, of their bounden duty to render them not 

 unfit for human occupation. 



But although the magnitude of the evils resulting from the 

 neglect of the conditions of Public Health, gives to this sub- 

 ject the first claim on our consideration, yet it is not the less 

 important that every individual should acquire as much 

 knowledge of the constitution of his body, and of the right 

 means of keeping it in working order, as will save him from 

 seriously damaging either himself or other people by his 

 ignorance of such matters. It is less than ten years since a 

 fearful sacrifice of life occurred among the deck-passengers on 

 board the Irish steamer " Londonderry," who were ordered 



