202 
Mean Annual Death- 
Eatio. 
Density. 
Births. 
Deaths. 
Annual Increase 
of Population. 
Persons to a 
Square Mile. 
15 . 
39 
315 
35-11 
22-00 
11-99 
15 . 
17 
166 
30-22 
16-75 
14-69 
18 . 
20 
186 
32-19 
19-16 
7-53 
21 . 
23 
379 
35-78 
21-88 
13-82 
24 . 
26 
1718 
38-75 
24-90 
18-59 
27 . 
30 
4499 
40-16 
28-08 
13-28 
32 (Manchester) 
12-375 
37-33 
32-49 
3-22 
39 (Liverpool) 
65-823 
37-57 
38-62 
— 12-33 
The law of increased mortality with increased density of 
population is, on the large scale, so definite and certain that 
Dr. Farr has Been able to construct a formula by which in 
many cases the mortality can be calculated from the den- 
sity — and if accurate data were obtainable it might even be 
possible to ascertain what increase of mortality might have 
been expected to result from the increased tendency of 
populations to aggregate themselves together. We cannot 
state the problem quite so definitely as this would imply, 
but if we take Dr. Farr’s estimate of 5 millions of additional 
inhabitants in our towns, and apply to this the usual urban 
rate of 24 as distinguished from the rural rate of 19 per 
1,000, we obtain an excess of 25,000 deaths that would 
have to be placed to the account of overcrowding. 
The fact that, on the whole, the mortality has remained 
stationary during the last 80 years, shows that 25,000 lives 
must have been saved by other means, and hence that some 
infiuences have been at work to mitigate the evil effects of 
overcrowding. What these infiuences are is made at least 
very probable by the fact that, in most of the notable excep- 
tions to Dr. Farr’s law, sanitary improvements have been car- 
ried out for a good many years. In the following examples 
