Page:Encyclopædia Britannica, Ninth Edition, v. 19.djvu/535

Rh  .—The characteristics of a population from the point of view of, which term “Altersaufbau” can only be treated very generally. TableV. on p.514 is quoted by Haushofer (p.213) from Von Scheel’s Handbuch der Statistik. This “ scale” shows us the proportion in which persons of various categories of are found combined to form populations. The general characteristics of the groups are tolerably obvious. It must be remembered that after thirty the periods are decennial. The difference between the scale of  and that of  is considerable. In the, owing mainly to the fact that are usually, a much larger proportion of the population than in  are under thirty  of. On the other hand the scale of  presents a feature of an opposite kind, namely, a deficiency of persons under fifteen  of, and an excess of those over forty, as compared with the average of. This conformation of the scale may be compared with that of, where the number of  is larger and the number of persons over forty less than the average. It is probable that the smaller number of in the one case and the larger in the other directly lead respectively to a smaller infant mortality in  than in. As M.Block observes (Traité, p.409), “Nous avons moins d’; mais, grâce à une moindre mortalité dans le, nous avons plus d’.” It is obvious that cæteris paribus it is easier to pay the requisite attention to the rearing of a small number of than to do the same for a larger number. Careful inquiries into scales are of very recent origin, the data required for evaluating those relating to earlier periods being absent. Moreover, erroneous statements as to their are made by a much larger number of persons than might be supposed, sometimes from carelessness or ignorance, but also intentionally. The tendency of over twenty-five to understate their, combined with overstatements of  by  and young  under twenty, always tends to make the twenty to twenty-five section of the  scale unduly large (see Census of England and Wales, 1881, vol.iv., “General Report”). We must regard even the scales now in existence as merely first approximations, for it is evident that observations obtained from several es must be reduced and combined before we can feel certain that accidental causes of error have been eliminated. This is all the more necessary as the scale of any given population cannot be regarded as fixed, any more than the magnitude of the population itself, both being liable to modifications arising out of the varying dynamical conditions existing at different periods. And this brings us to the second portion of our inquiry, in which we shall indicate in the most general way the nature of the proximate causes which underlie the phenomena of population considered as a fact existing at a.

II. Population, dynamically considered, is the result of two pairs of opposing forces, whose combined action may, for convenience, be theoretically conceived of as balancing each other, but which never do so balance as a matter of fact. A comparison of two successive es invariably shows some “movement of population.” In nearly all the movement shown is one of growth when the body of population examined is large. The population of a or a small  may, quite conceivably, show a reduction in number for the period between two es, but this can hardly be the case with a large, and still less with a, unless as the consequence of some great calamity such as an  or a  or a change in the  or  of the  inhabited. A great, of course, produces a certain retardation of the rate of increase. Although some of the  of the  are rapidly disappearing, the tendency of the population of the whole  is evidently to increase—at what rate it is impossible to say, for reasons already mentioned; and our inquiry will, therefore, be confined to  regarding whose population we have comparatively accurate information for an adequate number of. The causes of the movement of population are internal and external. The internal arise out of the numerical relation between the and deaths of a given period, there being an increase when there are more than deaths, a decrease in the contrary case. Haushofer expresses this by a formula which is sometimes convenient:—“There is an increase where the intervals between successive are smaller than those between successive deaths” (p.115). The external are and. The intensity of these two forces operating on population depends on a variety of causes, into which we do not propose to enter. Generally speaking, it may be said that “new”, where the density of population is small, attract from  in which the density of population is great. The density of population is expressed by the figure denoting the number of inhabitants per  (or  ) of the territory they occupy. For a discussion of the various, , and causes which determine density of population, we must refer our readers to the works of Haushofer (p.173) and Block (p.456). Before analysing the components of the movement of population it will be useful to examine briefly that movement itself, and ascertain what is its normal rate in. The mode of expressing this rate which is most commonly adopted in the exposition of of population is to state the number of  in which a given population “doubles itself.” It is not a very  method of expressing the facts, since it assumes that the rate of a few  will continue for a period of many, but, in deference to custom, we give a table constructed in accordance with it.

We now proceed to give a table (VII.) constructed by SignoreLuigi Bodio on the best principles, which shows the rates of increase of a number of, for two distinct periods, taking account of the important changes 