advance, for purposive planning is one. The explanation, people will say, is simple; ebb and in a number of deaths was as follows:— 1790 40,000 1520 243,000 1830 337,620 1840 661,254 1850 1,767,841 1800 3:392,980 1870 4,901,980 1880 7,026,820 1890 . 10,419,608 1900 . 13,537,097 I910 . 18,453,320 1920 » 22,733,254 This computation would apparently have double the rel- ative