KAMITN, ABII'L ABBAS ABDALLA AL, Caliph of Bagdad, of the Abbaside dynasty, and son of Haroun al-Raschid, was b. in Bagdad, 780, and brought up along with his brothers under the care of the most illustrious men of the time. In 800 A.D. he was invested with -the government of Kliorassan; and after dispossessing his' elder brother, Al-Amin, who -had ascended the throne on the death of their father, became caliph, Oct. 4, 813. His reign was disturbed by internal dissensions, and rebellions Of the outlying provinces. Africa and Yemen declared themselves independent, the' subjection of Egypt, Syria, aud Mesopotamia was merely nominal, but the rest was well and beneficently governed. Civilization advanced with rapid strides; ruined towns and devastated tracts were restored; and distributions from the royal treasury made to those who had suffered from earthquakes, drought, or any other unavoidable cause. ln 827, Mamun abjured the 4orthodox religion, and joined the heterodox sect called Motasalis, compelling a number of his subjects to follow his example. Towards the close of his reign. a war broke out with the Greek emperor Theophilus, and soon afterwards Mamwa died, Aug. 9, 834. Mamun -was the most learned and liberal of the Abbaside caliphs, and is said to have expended -300,000 dinars (2137,500) on the translation of the works of the ancient Greek philosophers into Arabic, thes3 works having been presented to him by the Byzantine emperor. He highly encouraged mathematics and astronomy, founded observatories at Bagdad and Kasiun (near Damascus), caused a, degree of latitude to be measured, and the obliquity of the eclipuc to be estimated. His new city of Bagdad became the abode of mei] of science and letters, who flocked to it from all quarters; and Man= himself personally superintended their labors. Mamun has left three works, two of which are on religious subjects MAN. Under this heading, it is proposed to consider various topics relating to the physiology and natural history of man, which have not been treated of in independent articles, such as the development of the physical qualities of man, the distinctive. characteristics of man, and the antiquity of the human race. The question of the races or varieties of man has been already discussed in the article ETHNOLOGY; and for infor mation regarding the mental and social nature of man, the reader is referred to the articles ETHICS, INSTINCT, INTELLECT, MIND, etc.
In tracing the development of the physical qualities, we shall follow the arran,gement pursued by Quetelet in his celebrated treatise Sur l'Homme.
It is a very remarkable fact, the true causes of which we do not know, that more boys are born annually than girls. Taking his data from the principal European states, M. Bickes (quoted by Quetelet), who has collected more than 70,000,000 of observations, finds that in Europe generally 106 males are born to 100 females. In Great Britain, the ratio is not quite so high, being 104.75 to 100. To some extent, the age of the parents influences the sex of the children, and Mr. Sadler was led to the conclusion, that "the
ratio in which the sexes are born is regulated by the difference of age of the parents, ia such a manner that the sex of the father or the mother will preponderate beyond the average of the total number of births, according to the party which has the excess of age.''' The probable value or duration of life immediately after birth is, in general, about 25. years in Belgium (Quotelet), 32.2 in France, 33 years in England (Rickman), and 47.2 ini Geneva (Lombard). Towards the age of five years, the chances of prolonged life for both sexes is greatest, ranging froin 48 to 50 years. It is impossible to state with scientific precision what is the natural length of a man's life, when all abnormal disturbing causes are removed; but so few persons exceed the age of 100 years that a century may be taken as the limit of man's existence.
The development of the height, weight, and strength, at different ages, has been studied by Quetelet, J. D. Forbes, Dauson, and others. From a large number of obser vations made by Quetelet in Belgium, he deduces the following conclusions: 1. Frotn birth there is an inequality both in weight and height between children of the two sexes: the average weight of a boy at birth being 3.20, and that of a girl 2.91 kilograms (1 kilogram=2.2 Ills.); the height of a boy being .496, and that of a girl .483 meters (1 meter=3.28 ft.). 2. The weight of a child diminishes slightly towards the third day after birth, and does not begin to increase sensibly until after the first week_ 8. At equal ages, the boy is generally heavier than the girl. It is only at about the age of 12 that the individuals of both sexes are of the same weight. Between 1 and 11 years the difference in weight ranges frbm a kilogram to a kilogram and a half; between 16 and 20, it is nearly- 6 kilo,grams; and after this period, 8 to 9 kilograms. 4.When. man and woman have attained their full development, they weigh almost 20 times as much as at birth; while their height is about 31, times greater than it was at that period., 5. In old age, man and woman lose about 6 or 7 kilograms in weig,ht, and 7 centi meters in height. 6. Man does not acquire his complete growth till after he has com pleted his 25th year; he attains his maximum weight at 40, and begins to waste sensibly after his 60th year. 7, Woman attains her maximum weight at the age of 50. During her reproductive period, the increase of her weight is very slight. 8. The weight of individuals who have been measured, and who were fully developed and well formed, varies within extremes which are nearly as 1 to 2; while the height varies within limits which at most are as 1 to as may be seen from the following observed values: Quetelet instituted a series of experiments on the strength of persons of both sexes at various ages. He determined both the lumbar power (the weight that could be carried on the back) and the power of the hands by means of Regnier's dynamometer.