246 



NATURE 



\ytily 10, 1879 



Roughly speaking, a line striking northward from [.the 

 head of the Bay of Bengal, to the Himalayas, then 

 turning westward and skirting the southern flanks of that 

 great mountain-chain, passing north of Cashmere, and in 

 a westward direction to the Sea of Aral, the Caspian, and 

 the Ural Mountains, divides the area occupied by people 

 of each type, those to the east and north of this line being 

 mainly Mongolians, and those to the south and west 

 mainly Caucasians. 



The people of India proper, except in the extreme 

 north and north-east, belong mainly to the Caucasian 

 division. It has been thought that other races have 

 contributed a share to the composition of the present 

 population of the Peninsula, having been the earliest 

 inhabitants of the land, and forming, as it were, a sub- 

 stratum of the existing population ; these are : — I. 

 'Negritos, allied to the Andaman Islanders: II. Aus- 

 traloids, allied to the modern Australians. The search 

 for evidence for or against the exiitence of these 

 elements in the population of India must naturally be 

 sought for among the tribes which retain more or less of 

 their barbarous condition. 



With these must be classed the Veddahs of Ceylon. 

 Many of these people have become civilised, but the wild or 

 " Rock Veddahs" live in a most primitive state of social 

 culture, without clothing, agriculture, or fixed dwellings. 

 They are a dwarfish, stunted race, of blackish complexion, 

 and with straight, though generally unkempt and shaggy 

 hair. The condition of their bones and other physical 

 characters give the impression of their being a race 

 degenerated and enfeebled by generations of privation 

 and other circumstances adverse to full development. 

 There are no Veddah skeletons in the College Museum, 

 but as many as seven crania ; one of them, that of a 

 woman, is the smallest adult skull in the whole collection. 

 Its cerebral capacity measuring only 960 c.c. (586 c. ins.). 

 They are all dolichocephalic, the average latitudinal index 

 being yi'l, and the average altidudinal index 86'i. Their 

 prognathism is not very marked, and the nasal index is 

 medium, averaging 5o"3. They enter rather into the type 

 of the lower grades of the inhabitants of Bengal. 



The present population of India, excluding the Mongo- 

 loid people of the north and east, is separated by language 

 into two great divisions — (l) The Aryans, and (2) The 

 Non-Aryans, the majority of whom speak one of the 

 agglutinative tongues collectively called Dravidian. The 

 Aryans came into India by the north-west by way of the 

 Punjaub, about 1,500 years before our era, as is supposed. 

 They now occupy the great alluvial plains of the Indus 

 and Ganges between the Himalayas and the elevated 

 plateau of Central India, and have spread southwards 

 along both coasts as far as Ceylon. 



The Dravidians, who occupy the greater part of the 

 country southwards from the Nerbudda River, are sup- 

 posed to be descended mainly from the people who in- 

 habited the country before the Aryan immigration. They 

 are again divided into two groups — {(i) The civilised Dra- 

 vidians, speaking Tamul, Telugu, Canarese, &c., and ifi) 

 The wild tribes of the mountainous districts of the in- 

 terior. These " Hill Tribes," as they are often called, 

 are of great interest to the ethnologist, as they represent 

 the oldest stratum of the population. By their languages 

 they are divided into two groups — (i) Those that speak 

 Dravidian, the Gonds, the Khonds, the Oraons, &c.; 

 ^(2) The Munda or Kolarian family, composed of numerous 

 tribes called Coles, Hos, Moondahs, Santals, Billahs, &c. 

 Very little is known of the physical characters of these 

 people. . 



Dr. John Shortt has lately sent to the Museum a series 

 of twenty skulls belonging to the tribes of Maravars, who 

 inhabit the Madura district in the south of the peninsula. 

 He has also sent a series of equal number to the Museum 

 of the Paris Anthropological Society, which has been de- 

 scribed by M. Callamand in a recent number of the 



Revue iVAuthropologie. As regards the capacity, the 

 average in the Paris skulls is 1,281 c.c, in those sent to 

 the Museum, 1,268 c.a The average lengths are respec- 

 tively i74"5 and i75'6, but in the former the projection of 

 glabella is included. The average breadth is 131 in both; 

 the latitudinal index is 746 in the one and 751 in the other 

 series ; the altitudinal, the nasal, and the orbital indices 

 are respectively 752 and 758, 521 and 510, 839, and 854. 

 These skulls, on the whole, differ totally from those of the 

 Andamanese, especially in the great development of the 

 occipital region. Nor do theypresent any striking resem- 

 blances either to those of the Australians, or to any of the 

 Mongoloid races. Their characters do not differ much 

 from those of the mixed population of Bengal generally. 

 These Maravars may not belong to the races among which 

 the characters of the original hill-tribes should be looked 

 for, and no evidence has yet been found of cranial con- 

 formation bearing out the view of the Australian affinities 

 of these people, derived from external appearance. The 

 presence of a Negrito, i.e., woolly-haired and brachy- 

 cephalic, element in the population of India, is also based 

 at present on very slender evidence. 



(To be continued) 



ON THE SECULAR EFFECTS OF TIDAL 

 FRICTION 1 



IN three papers, read at different times before the Royal 

 Society, the author has considered the theory of the 

 tides of a viscous spheroid, and the perturbations of the 

 rotation of the spheroid caused by the attraction of the 

 tide-raising satellite ; the direction of that investigation 

 was governed by considerations of applicability to the 

 case of the earth, moon, and sun. 



In the paper, of which we are here giving an account, 

 the question is considered both from a more general 

 and from a more special point of view than in the previous 

 papers. For it is here supposed that there is only a single 

 tide-raising body or sateUite which moves in a circular 

 orbit in the equator of the planet, but the orbital motion 

 may be cither consentaneous with or adverse to the 

 planet's rotation. The tides supposed to be raised in the 

 planet by the attraction of the satellite are of any kind 

 whatever, provided that there is a frictional resistance in 

 the planet to the tidal motion. The results are therefore 

 applicable alike to the hypothesis of bodily tides, or to 

 that of oceanic tides. 



It results from a general mechanical principle that in 

 whatever way the satellite and planet interact, the whole 

 moment of momentum of the rotation of the system must 

 remain constant ; whilst, as there is a frictional resistance 

 in the planet to the tidal motion, the whole energy of the 

 system, viz., the sum of the potential and kinetic energies, 

 must diminish. The method employed to trace the effects 

 of tidal friction consists in drawing two curves, one of 

 which represents the constancy of the moment of mo- 

 mentum, and the other of which gives the energy of the 

 system for each configuration. 



Then if we conceive a system of a planet and sateUite 

 started in such a way as to be represented by a given 

 point on the curve of conservation of moment of mo- 

 mentum ; and if we imagine this point linked to its corre- 

 sponding point on the curve of energy, since the energy 

 must degrade, the point on the curve of energy must 

 always slide down a slope and carry with it the point on 

 the curve of momentum. 



It is thus possible to track the nature of the changes in 

 the configuration of the system, but the method gives no 

 clue to the time occupied by those changes. This com- 

 parison of the energy with the moment of momentum of 

 the system by a graphical method was suggested to the 

 author by Sir William Thomson. 



■ A paper read before the Royal fociety on June 19, 1879, ly G. H. 

 Darwin. 



