1910—11.] Incidence of Mortality from Pulmonary Tuberculosis. 359 
certain small towns were transferred to the large town districts. In 
1901 a further change was made, the minimum population of a principal 
town being raised to 30,000. There are now fifteen of these, viz. those 
above enumerated, and Govan, Partick, Kirkcaldy, Hamilton, and Motherwell. 
An effort has thus been made to retain the distinctive feature of the 
population of each of these districts as regards aggregation on area, which 
was adopted in 1871. The population of Scotland was distributed at 
census periods as follows : — 
Principal 
Towns. 
1881. 1,411,536 
1901. 1,950,297 
Large Small 
Towns. Towns. 
388,797 790,796 
578,769 897,326 
Mainland Insular 
Rural. Rural. 
1,014,056 130,388 
929,042 116,505 
The population of the insular rural district is so small in comparison with 
that of the others that its statistics are not fully comparable, and, besides, a 
large number of the deaths in this district are not medically certified as to 
cause. For these reasons the statistics of the first four districts only are 
given. These are set out, corrected to sex and age constitution of Scotland 
1901, in Table IV. The rate of diminution among both sexes, taken together 
and in each sex, is greatest in the principal towns, and least in the 
mainland rural. In all the districts the diminution among females is 
greater than among males. In the principal town districts the female 
death-rate exceeded that of males till quinquennium 1886-90,* and in 
the mainland rural districts till 1896-1900, while in the large town and 
small town districts it has exceeded that of the males during the entire 
period 1871-1907. 
Effect of Urban and Rural Conditions . — In order to study this question 
in sufficiently large populations, the death-rates of the principal town and 
large town districts combined, and of the small town and mainland 
rural districts combined, have been calculated and are set out in Table V. 
For purposes of comparison the rates for Scotland, excluding the insular 
rural districts, are also given. The urban area so constituted had an 
average population in 1891-1900 of 2,239,487, and the rural area of 
1,832,601. 
A study of Table V. shows that the reduction in the mortality has been 
greater in the urban than in the rural area (1) among both sexes taken 
together, and (2) among females both absolutely and in comparison with 
that among males. 
* The female rate did not exceed the male rate in all the principal towns. In 
Edinburgh, e.g ., it has been always much less than the male rate. This is discussed later. 
