of births, deaths, and marriages.

36 would double the population in less than 21 years. If we take the 20 years from 1711 to 1731, the average proportion of the births to deaths will appear to be about 17 to 10, a proportion which (according to Table I. page 30) would double the population in about 35 years. But if instead of 20 years we were to take the whole period of 64 years, the average proportion of births to deaths turns out to be but a little more than 12 to 10, a proportion which would not double the population in less than 125 years. If we were to include the mortality of the plague, or even of the epidemic years 1736 and 1737, in too short a period, the deaths might exceed the births, and the population would appear to be decreasing.

Sussmilch thinks that instead of 1 in 36, the mortality in Prussia after the plague might be 1 in 38; and it may appear perhaps to some of my readers, that the plenty occasioned by such an event ought to make a still greater difference. Dr. Short has particularly remarked that an extraordinary healthiness generally succeeds any very great mortality;' and I have no doubt that the observation is just comparing similar ages together. But

History of air, seasons, &c. vol. ii. p. 344.

Effects of epidemics on registers

under the most favorable circumstances, infants under three years are more subject to death than at other ages; and the extraordinary proportion of children which usually follows a very great mortality counterbalances at first the natural healthiness of the period, and prevents it from making much difference in the general mortality.

If we divide the population of Prussia after the plague by the number of deaths in the year 1711, it will appear that the mortality was nearly 1 in 31, and was therefore increased rather than diminished, owing to the prodigious number of children born in that year. But this greater mortality would certainly cease as soon as these children began to rise into the firmer stages of life; and then probably Sussmilch's observations would be just. In general however, we shall observe, that a great previous mortality produces a more sensible effect on the births than on the deaths. By referring to the table it will appear, that the number of annual deaths regularly increases with the increasing population, and nearly keeps up the same relative proportion all the way through. But the number of annual births is not very different during the whole period, though, in this time, the population had more than doubled itself; and therefore the

of births, deaths, and marriages.

proportion of births to the whole population, at first, and at last, must have changed in an extraordinary degree.

It will appear therefore how liable we should be to err in assuming a given proportion of births for the purpose of estimating the past population of any country. In the present instance it would have led to the conclusion, that the population was scarcely diminished by the plague, although from the number of deaths it was known to be diminished one third.

Variations of the same kind, though not in the same degree, appear in the proportions of births, deaths, and marriages, in all the tables which Sussmilch has collected; and as writers on these subjects have been too apt to form calculations for past and future times from the proportions of a few years, it may be useful to draw the attention of the reader to a few more instances of such variations.

In the churmark of Brandenburgh,' during 15 years ending with 1712, the proportion of births to deaths was nearly 17 to 10. For 6 years ending with 1718, the proportion sunk to

1 Sussmilch's Gottliche Ordnung, vol. i. Tables, p. 88. vol. ii.

g

Effects of epidemics on registers

13 to 10; for four years ending with 1752, it was only 11 to 10; and for 4 years ending with 1756, 12 to 10. For 3 years ending with 1759, the deaths very greatly exceeded the births. The proportion of the births to the whole population is not given; but it is not probable that the great variations observable in the proportion of births to deaths should have arisen solely from the variations in the deaths. The proportion of births to marriages is tolerably uniform, the extremes being only 38 to 10, and 35 to 10, and the mean about 37 to 10. In this table no very great epidemics occur till the 3 years beginning with 1757, and beyond this period the lists are not continued.

In the dukedom of Pomerania,' the average proportion of births to deaths for 60 years from 1694 to 1756 both included, was 138 to 100; but in some of the periods of six years it was as high as 177 to 100, and 155 to 100. In others it sunk as low as 124 to 100, and 130 to 100. The extremes of the proportions of births to marriages in the different periods of 5 and 6 years were 36 to 10, and 43 to 10, and the mean of the 60 years about 38 to 10. Epidemic years appear to have

1 Sussmilch, vol. i. Tables, p. 91.

of births, deaths, and marriages.

occurred occasionally, in three of which the deaths exceeded the births; but this temporary diminution of population produced no corresponding diminution of births; and the two individual years which contain the greatest proportion of marriages in the whole table occur, one the year after, and the other two years after epidemics. The excess of deaths however was not great till the 3 years ending with 1759, with which the table concludes.

In the neumark of Brandenburgh,1 for 60 years from 1695 to 1756 both included, the average proportion of births to deaths in the first 30 years was 148 to 100, in the last 30 years 127 to 100, in the whole 60 years 136 to 100. In some periods of 5 years it was as high as 171 and 167 to 100. In others as low as 118 and 128 to 100. For 5 years ending with 1726, the yearly average of births was 7012; for 5 years ending with 1746, it was 6927; from which, judging by the births, we might infer that the population had decreased in this interval of 20 years; but it appears from the average proportion of births and deaths during this period, that it must have considerably increased notwithstanding the intervention of some epi

1 Sussmilch's Gottliche Ordnung, vol. i. Tables, p. 99.