1910-11.] Incidence of Mortality from Pulmonary Tuberculosis. 353 
quinquennia. For a proper comparison of the series of rates, however, 
account must be taken of the change in sex and age constitution of the 
population during the period under review, seeing the mortality varies 
greatly according to age and, though in a lesser degree, according to sex. 
From the censuses of Scotland 1861 and 1901 the following table has 
been prepared : — 
Age and Sex Constitution of Population in Scotland 
per 10,000. 
Census 1861. 
Census 1801. 
Males. 
Females. 
1 
Males. 
Females. 
0-5 
692 
670 
600 
592 
5-10 
602 
584 
557 
544 
10-15 
539 
515 
533 
517 ! 
15-20 
491 
513 
515 
504 
20 -25 
416 
499 
470 
498 
25-30 
331 
430 
405 
442 
30-35 
296 
364 
337 
373 
35-40 
256 
312 
297 
325 
40-45 
241 
290 
265 
283 
45-50 
204 
235 
224 
242 
50-55 
184 
222 
187 
208 
55-60 
140 
168 
147 
172 
60-65 
133 
174 
124 
157 
65-70 
80 
107 
82 
111 
70-75 
58 
84 
59 
84 
75 + 
66 
95 
55 
91 
This change in the sex and age constitution of the population is due 
chiefly to the decrease in the birth-rate, modified to some degree by 
changes in the death-rate. In Table I. the figures given in columns 5, 6 
and 7 are all comparable, as they show the death-rates which would have 
resulted from the rates prevailing in Scotland at the several age periods 
if the sex and age constitution of the population in all of the quinquennia 
had been the same as that of Scotland at census 1901. Columns 8, 9, and 
10 show the ratio (as whole numbers) of the rates thus corrected to that of 
1866-70 taken as 100. It will be observed that this correction raises 
the death-rate in each case, showing that the sex and age constitution of 
the population from 1861-1900 was favourable to a low death-rate from 
tuberculosis of the lungs as compared to that at census 1901. The rates 
for Ireland have been similarly corrected to make them comparable with 
those of Scotland. The rates for England and Wales are uncorrected. 
vol. xxxi. 23 
