The preparation of the new issue has involved unusual labor, as it was necessary to examine all the statistics which have appeared since 1882. For many countries which have no censuses Dr. Supan has undertaken special investigations as to population; in this way he has dealt with Africa, Turkey in Europe and Asia, Arabia, China, East India Islands, etc. Dr. Supan is responsible for the sections dealing with Africa, America, Australia, the Oceanic Islands, and the polar regions; all colonial statistics have fallen to his share, while Prof. Wagner has looked after Europe and Asia. In several respects the arrangements of the various sections is an improvement on that of former issues.
In 1866 Behm estimated the population of the earth at 1,350,000,000. In the sixth issue (1880) of the Bevölkerung der Erde the number had apparently grown to 1,456,000,000, showing an ostensible increase of 106,000,000 in fourteen years. But this difference was really due to more accurate statistics and estimates rather than to actual growth. It was somewhat alarming, however, when in the 1882 issue the total population of the earth appeared as 1,434,000,000, showing a seeming decrease in two years of 22,000,000. But this was largely accounted for by the fact that new investigations compelled the reduction of the estimated population of China from 405,000,000 to 350,000,000. The estimate, reached in the present issue of 1891 for the total population of the earth is 1,480,000,000, showing an increase of 46,000,000 over the estimate for 1882, being at the rate of 5,750,000 per annum. This estimate is 3,000,000 less than that of Levasseur in 1886, partly due to the fact that Levasseur took higher estimates of the population of China and of Africa than have Wagner and Supan. But as the data for a very large area of the inhabited globe are to a considerable extent based on guesswork, it is no wonder that estimates should differ, and that we can not be sure of the population of the world to within 60,000,000, possibly 100,000,000, either way. In 1880 Prof. Wagner found that, of the total population in that year, precise data based on actual enumeration (censuses or registration) were available for only 626,000,000 out of 1,401,000,000—that is, forty-four per cent of the total. This population has meanwhile increased to 737,000,000 (though the increase in some cases is only apparent); to this must be added 99,000,000, for which, since 1880, exact enumerations have been substituted for vague estimates. This gives 836,000,000 out of the total of 1,480,000,000 of people—i. e., between fifty-six and fifty-seven per cent—of whom fairly precise enumerations have been taken. True, in this is included 113,000,000 (the population of the Russian Empire) of whom a general census, in the modern sense of the term, has not been taken, except in the case of one or two provinces. Although, when the figures are looked at by
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