On the alleged Increase of Cancer. 215 



septennial periods. The annual returns for England and Wales and 

 for Ireland came down to 1890 inclusive, but for Scotland the last 

 year available was 1889, and the several observations were there- 

 fore closed at these points respectively. In the case of Ireland, we 

 could not obtain the deaths from cancer prior to 1864, and we have 

 therefore been limited to the three years 1864-66 for Ireland, instead 

 of the seven years 1860-66. 



For purpose of reference, and in case other inquirers desire further 

 to investigate our figures, we give them in Tables II to V in the 

 Appendix, arranged as above described. 



From the figures in Tables II to V may be at once obtained the 

 death-rates from cancer for each period of years, and for each age 

 interval. As the resulting rates are necessary to the subsequent 

 calculations, they are given in Tables VI to IX in detail, and are 

 expressed as rates per million, in order to reduce the number of 

 decimal places. The numbers, as might have been expected, run. 

 irregularly, but, on account of the method of grouping of the figures 

 later on, this irregularity is not of any practical importance. 



The rates of mortality given in Tables VI to IX, notwithstanding 

 the considerable numbers on which they are based, do not run with 

 sufficient regularity to disclose the general law by which they are 

 governed ; and, even though they did run regularly, it would not be 

 easy to discover from them that law. Moreover, it is not the object 

 of the present inquiry to ascertain the liability to cancer at different 

 ages, but to discover whether cancer is on the increase or not in the 

 community generally. It is therefore necessary so to group the 

 figures that the total cancer experienced at all ages in any particular 

 period of years may be compared with the total cancer experienced in 

 any other period. If we take the rates of mortality given in Tables 

 VI to IX and multiply them into the populations of Table B, we 

 shall have the desired results. The sum of the products for any 

 particular period of years will give the number of deaths from cancer 

 per annum among 1,000,000 persons aged 25 and upwards. Then by 

 comparing the sum for, say, the period 1860-66 with that for the 

 period 1881-87, we can ascertain in which direction the apparent 

 death-rate from cancer is progressing. It will be observed also that 

 by pursuing this course the observations for all the different localities 

 and all the different periods of years are reduced to one common 

 standard, and the errors are eliminated which would arise from 

 variations in the age distribution of the populations. Tables X and 

 XI display these results in their final form, the ratios for ages under 

 55 and over 55 respectively, as well as for all ages, being given in 

 them. Some persons may be glad to be able to investigate the 

 matter for these two great periods of life, although we do not propose 

 to include this branch of the subject in our inquiry. 



VOL. LIV. Q 



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