ページの画像
PDF
ePub

On the fruitfulness of marriages.

proportion of marriages to deaths will be as 1 to 3.6. Supposing the age of marriage in England about 7 years earlier than the mean age of death, the increase in these 7 years according to the present progress of population of lżó yearly would be .06, and the proportion living to' marry would be 200 out of 381, or rather more than half.' The mar. riages compared with the births 4 years later will give 4.136 for the prolificness of marriages.

. Births to deaths do, mean is, and on the supposition that the age of marriage is 28, the difference would be 7. With regard to the allowance which I have made here and in a former chapter for the omissions in the births and deaths, I wish to observe, that as I had no very certain and satisfactory grounds on which to proceed, it may be incorrect, and perhaps too great, though assuming this allowance the mortality appears to be extraordinarily small considering the circumstances of the country. It should be remarked however, that in countries which are different in their rates of increase, the annual mor. tality is a very incorrect' criterion of their comparative healthiness. When an increase is going forward the portion of the population which becomes extinct every year is very different from the expectation of life, as has appeared very clearly in the cases of Russia and America just noticed. And as the increase of population in England has of late years been more rapid than in France, this circumstance will undoubtedly contribute in part to the great difference in the annual mortality.

On the fruitfulness of marriages.

These instances will be sufficient to show the mode of applying the rules which have been given in order to form a judgment, from registers, of the prolificness of marriages, and the proportion of the born which lives to marry.

It will be observed how very important the correction for second and third marriages is. Supposing each marriage to yield 4 births, and the births and deaths to be equal, it would at first appear necessary that in order to produce this effect, exactly half of the born should live to marry; but if on account of the second and third marriages we şubtract * from the marriages, and then compare them with the deaths, the proportion will be as I to 4$, and it will appear that instead of one half it will only be necessary that 2 children out of 4 should live to marry, Upon the same principle if the births were to the marriages as 4 to 1, and exactly half of the born live to marry, it might be supposed at first that the population would be stationary, but if we subtract 1 from the marriages, and then take the proportion of deaths to marriages as 4 to 1, we shall find that the deaths in the registers compared with the marriages would only be as 3j to l; and the births would be to the deaths

On the fruitfulness of marriages.

as 4 to 3, or 12 to 10, which is a tolerably fast rate of increase.

Three causes appear to operate in producing an excess of the births above the deaths, 1. the prolificness of marriages ; 2. the proportion of the born which lives to marry, and 3. the earliness of these marriages compared with the expectation of life, or the shortness of a generation by marriage and birth, compared with the passing away of a generation by death. This latter cause Dr. Price seems to have omitted to consider. For though he very justly says, that the rate of increase, supposing the prolific powers the same, depends upon the encouragement to marriage and the expectation of a child just born; yet in explaining himself, he seems to consider an increase in the expectation of life, merely as it affects the increase of the number of persons who reach maturity and marry, and not as it affects, besides, the distance between the age of marriage and the age of death. . But it is evident that if there be any principle of increase, that is, if one marriage in the present generation yields more than one in the next, including sccond and third marriages, the quicker these gene. rations are repeated, compared with the passing

On the fruitfulness of marriages.

away of a generation by death, the more rapid will be the increase.

A favorable change in either of these three causes the other two remaining the same, will clearly produce an effect upon population, and occasion a greater excess of the births above the deaths in the registers. With regard to the two first causes, though an increase in either of them will produce the same kind of effect on the proportion of births to deaths, yet their effects on the proportion of marriages to births will be in opposite directions. The greater is the prolificness of marriages the greater will be the proportion of births to marriages, and the greater is the number of the born which lives to be married, the less will be the proportion of births to marriages.' Con

1

[ocr errors]

Dr. Price himself has insisted strongly upon this, (vol. i. p. 270, 4th edit.) and yet he says, (p. 275.) that healthfulness and prolificness are probably causes of increase seldom separated, and refers to registers of births and weddings as a proof of it. But though these causes may undoubtedly exist together, yet if Dr. Price's reasoning be just, such coexistence cannot possibly be inferred from the lists of births and weddings. Indeed the two countries, Sweden and France, to the registers of which he refers as showing the prolificness of their marriages, are known to be by no means remarkably healthy ; and the registers of towns to which he alludes, though they

On the fruitfulness of marriages.

sequently if within certain limits, the prolificness of marriages and the number of the born living to marry increase at the same time, the proportion of births to marriages in the registers may still remain unaltered. And this is the reason why the registers of different countries with respect to births and marriages are often found the same under very different rates of increase.

The proportion of births to marriages, indeed, forms no criterion whatever, by which to judge of the rate of increase. The population of a country may be stationary or declining with a proportion as 5 to 1, and may be increasing with some rapidity with a proportion as 4 to 1. But given the

may show as he intends, a want of prolificness, yet according to his previous reasoning show at the same time great healthiness, and therefore ought not to be produced as a proof of the absence of both. The general fact that Dr. Price wishes to establish may still remain true, that country situations are both more healthy and more prolific than towns ; but this fact certainly cannot be inferred merely from lists of births and marriages. With regard to the different countries of Europe, it will generally be found, that those are the most healthy which are the least prolific, and those the most prolific which are the least healthy. The earlier age of marriage in unhealthy countries is the obvious reason of this fact.

1

« 前へ次へ »