We shall now introduce a brief account of some researches upon the height, weight, and strength of the human body, at different ages, prosecuted by M. Quetelet, of Brussels. Not having room for the numerical tables, or the particular observations, from which his general conclusions are derived, we must content our selves with a statement of the latter, and refer those of our readers who may be desirous of seeing the former, to the author himself. His deductions as to the growth of human stature are as follows : (1) the growth is most rapid immediately after birth ; it amounts in the first year of infancy to about two decimetres (nearly eight inches.) (2) The growth dimi nishes as the child advances towards the fourth or fifth year ; thus, during the second year his increase of height is only half what it was the first year, and during the third year it is not more than one-third. (3) After the fourth or fifth year, the stature increases pretty regularly until the age of sixteen, and the an nual growth is about fifty-six millim, (two inch.) (4) After puberty the stature still increases, though slightly ; thus, from the sixteenth to the seventeenth year, the increase is about four centim. (12 inch); and in the two following years, only two centim, and a half (one inch.) (5) The stature does not appear to be quite completed even at the age of twenty-five.- These observations refer only to absolute growth, but if the annual increase of stature be com pared with the height which has been attained, it will be found that the infant, after birth, increases in the first year by two fifths of his height ; in the second by one-seventh ; in the third by one-eleventh ; in the fourth by one-fourteenth; in the fifth by one-fif teenth ; in the sixth by one-eighteenth ; &c. so that the relative growth continually dimi nishes after birth.
In addition to these statements M. Quetelet has ascertained that the rules of growth are not the same in both sexes; 1st, because the female at birth is less than the male; 2dly, because her development is completed earlier ; idly, because her annual growth falls short of that of the male. It appears likewise that the stature of persons living in towns, taken at the age of nineteen, exceeds that of residents in the coun try by two or three centim (1 or 11 inch); and that the children of persons in easy circum stances, and those of studious habits, are gene rally above the middle height.* A memoir by the same author devoted to an examination of the weight of the human subject at different ages, contains a series of interesting conclusions,from which we select the following. (1.) At:the period of birth there is an inequality both as to weight and to stature,in the two sexes ; the medium weight of males being 3 kil. 20, (rather more than 7 lbs.), that of females 2 kil. 91, (about 61 lbs.); the height of the former Om. 496, (about 19 inch.); that of the latter Om. 483, (about 18 inch.) (2.) The weight of the infant diminishes the first three days after birth, and does not begin to increase till the second week. (3.) At the same age the male is generally heavier than the female; it is only about the twelfth year that their weights are equal. Between the first and eleventh year the
difference of weight is fiom 1 kil. to 1 kil. and a half; between sixteen and twenty, about 6 kil. and after this period from 8 to 9 kil. (4.) At full growth the weight is almost exactly twenty times what it was at birth, while the stature is only about three and a quarter more than it was at that period. This holds good with both sexes. (5.) In old age both sexes lose about 6 or 7 kil. of their weight, and 7 centim. of their height. (6.) During the growth of both sexes, we may reckon the squares of the weights, at the different ages, as proportional to the fifth powers of the heights. (7.) After full growth in each sex, the weights are very nearly as the squares of the heights. (From the two prece ding statements it may be deduced that the increase in the longitudinal direction exceeds that in the transverse, including in the latter both width and thickness.) (8.) The male at tains his maximum weight towards the fortieth year, and begins to lose it sensibly towards the sixtieth. The female does not attain her maxi mum weight till about the fiftieth year. (9.) The weights of full-grown and well-formed persons vary in a range of about 1 to 2, while the heights vary only from 1 to 1i. This state ment is deduced from the following table :t The last researches of this industrious ob server have been devoted to the muscular power of man at different ages, and have been but very recently In the course of his memoir he refers to two tables ; one stating the relative power of draught (la force renale), at the several periods ; the other, the relative ma nual strength (la force manuelle); in each case estimated by the dynamometer. The results are very much what might be expected a priori. It appears that the maximum of the " force renale " is at the age of twenty-five ; and that the difference in the extent of this kind of mus cular power between males and females, is less during childhood than at the adult age. Thus, in the former period the male surpasses the female by one-third, towards puberty by one half; and at full growth, his strength is double that of the other sex. The manual force is greatest at the age of thirty, and at all ages is greater in the male than in the female ; before puberty, in the ratio of 3 : 2, after this period, in the ratio of 9: 5. The average manual strength of a man is equivalent to 89 kil. and exceeds his weight by 19 kil., so that he might support himself by his hands only, even with a considerable weight attached to his feet.* This and the preceding memoirs, we are told by M. Quetelet, are extracted from a work which he is about to publish, entitled " Sur l'Homme et le developpement de ses facultes ; ou, Essai de Physique Sociale." We need scarcely add that we are justified in expecting from the specimens already presented to us, a series of valuable and highly interesting facts, together with deductions of no ordinary im portance and originality.