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, on forty-three tunes 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 f Londonderry,” who were ordered 
