8o 



NATURE 



[May 27, 1880 



the Malay (judging by the skeletons in the College 

 Museum) agree with the negro rather than with some 

 other branches of the so-called Mong:oloid races, as the 

 Eskimo and the Samoyede. But this is a subject for 

 further ebscrvation rather than hasty generalisation. 



The difference between the pelvis of the African negro 

 and that of the European has been pointed out by \'rolik 

 and others. It consists mainly in the increase of the 

 antero-posterior diameter as compared with the trans- 

 verse, expressed by the pelvic index, or ratio between 

 these diameters, the latter being taken as 100. In the 

 European male the average inde.x is 80, in negroes, 

 according to various observers, from 90 to 100. As in the 

 proportions of the limbs, many of the Mongoloid races 

 conform in the characters of the pelvis rather with the 

 negro than with the European. 



In the cranial characters the distinctions between the 

 negro and the white races are strongly marked. The 

 average capacity of the cerebral cavity is undoubtedly 

 smaller in the former, even in individuals of approxi- 

 mately the same height. It is, however, considerably 

 higher than in the Australian. The difference between 

 the average capacity of English and negro crania in the 

 College Museum is 123 cubic centimetre?, between the 

 latter and the Australian So c.c. Broca's totally independent 

 measurements of skulls at Paris give a difference in the former 

 case (Parisians being substituted for English) of 128 c.c, 

 and in thelatterof83c.c.,sothat the results are substantially 

 identical. The general form of the cranium is expressed 

 by the cephalic or latitudinal index, orrelation of breadth 

 to length, the latter taken as 100. The average index of 

 forty-two negroes of various tribes in the College Museum 

 is 73-6. Of these more than half are between 70 and 75, or 

 dolichocephalic; less than half are above 75, or mesati- 

 cephalic ; but very few are either below 70 or above 80. 

 The average index of eighty-five negroes from the West 

 Coast of Africa, measured by Broca, is 73-4, and of fifty- 

 three from East Africa, measured by Lederle, is 73^9 

 These remarkable agreements with our own measure- 

 ments show that between 7^ ani 74 may be fairly taken 

 as a general average of the cephalic index of the African 

 negro, and that he belongs, therefore, to the moderately 

 dolichocephalic races. The height, measured from the 

 basion to the bregma, is almost identical with the breadth, 

 the average of the forty-two College specimens giving 

 73'S- The negro skull in these proportions differs greatly 

 from that of the Fiji Islanders previously described. 

 Differences in the position of the foramen magnum, 

 in the angle formed by its plane, with the horizontal of 

 the skull, and in the various facial angles, which have 

 been pointed out as characterising the negro skull as 

 compared with that of the European, can only be ex- 

 plained by means of diagrams. The facial characters are 

 generally eminently characteristic. The forehead, though 

 narrow, is not retreating. The glabella and supra-orbital 

 ridges are sometimes well developed, but more usually 

 this region is smooth and flat. The orbits have a mode- 

 rate index, 85-5 (Broca), or 86-3 according to measure- 

 ments of the College collection. The nose is distinctively 

 platyrhine, the average index being 55 or 56. The nasal 

 bones are small and flat, their external surfaces directed 

 forwards, the two meeting in front at a very open angle, 

 instead of a narrow one as in Europeans. The lower 

 margin of the nasal aperture is usually rounded off instead 

 of sharp and strongly defined. Equally characteristic is 

 the prognathism, which is very rarely absent. The mea- 

 surement from the basion to the middle of the alveolar 

 border is greater than that from the basion to the naso- 

 frontal suture, whereas in Europeans the reverse is almost 

 always the case. 



The teeth are regular, well developed, and generally 

 free from caries. The third molars (wisdom teeth) appear 

 to be always in their place before the closure of the 

 basilar suture, whereas among Europeans they are often 



much later in coming into place. The size of the 

 teeth varies in different races, but hitherto no accurate 

 measurements have been made to express their differ- 

 ence. The length of the molar series, in a straight 

 line between the anterior edge of the first premolar 

 and the posterior edge of the third molar, may 

 be conveniently used to indicate the size of the teeth, 

 and called 1/. This may be compared with the length of 

 the cranio-facial axis, or basi-nasal length (B N), and a 



dental index formed from — ^ '°° . This will give at all 



B N *" 



events a fair approximation to the relative size of the teeth 

 compared with the skull, as the length B N is one of the 

 least liable to variation of any in the cranium. Un- 

 fortunately for the investigation, in a large proportion of 

 the crania in Museums the teeth are wholly or partially- 

 lost, and a larger number of specimens must be measured 

 than are at present available. The following indices 

 (which must be regarded as provisional) are however of 

 considerable interest. In the first place it must be 

 observed that the teeth of women, though smaller abso- 

 lutely, are larger relatively to the cranio-facial axis than 

 those of men. For instance, in Europeans the dental 

 index of males is 40'5, of females 42 'o. In AuTtralians 

 the disproportion is greater still, being 457 for the males, 

 and 484 for the females examined. In the following 

 table males only will be included. Europeans 40"5, 

 Ancient Egyptians 40-8, Hindoos 41 '2, American Indians 

 42'5, Chinese 43'S, African Negroes 439, Andamanese 

 44"2, Fijians 45-4, Australians 457. It will thus be seen 

 that in the size of the molar teeth the negroes hold an 

 intermediate position between Europeans and Australians, 

 but approaching nearer to the latter. The actual average 

 length of the molar series in European males is 40'8 

 millimetres, in Africans 45-4, in Australians 467. The 

 anthropoid apes give a higher index than that of any 

 of the races of man. 



(7\? it: conliiiiied.) 



ON SYSTEMATIC SUN-SPOT PERIODICITY 



A T the present moment, when a good deal of attention 



-'*■ is being directed to sun-spots and their possible 



influences, it may not be amiss to discuss the question of 



their systematic periodicity. 



We have to ask ourselves whether we can by a limited 

 application of labour so disentangle the apparently com- 

 plicated and capricious phenomena of sun-spots as to 

 exhibit certain well-defined recurring periods, the super- 

 position of which upon each other may ultimately explain 

 the march of these phenomena. It will be apparent that 

 su:h an analysis of the past is the first and indispensable 

 step towards any prediction for the future. I will now 

 bring before the readers of Nature the first results of 

 an attempt of this kind. As the subject will be more fully 

 discussed in another place, I will in the meantime mainly 

 exhibit the results obtained, referring as briefly as maybe 

 to the method used in procuring them. The method is 

 that which (in conjunction with Mr. Dodgson) I have 

 already brought before the notice of the Solar Physics 

 Committee and of the Royal Society. It has been applied 

 to thirty-six years of sun-spot observations, beginning 

 with 1832 and ending with 1867. The first portion of 

 these has been derived from the records of Hofrath 

 Schwabe, the second from those of Carrington, while the 

 latter portion has been derived from De la Rue's Kew 

 series. My first object has been to ascertain to what 

 extent these records exhibit indications of certain syste- 

 matic inequalities having periods not far differing from 

 twenty-four days. I will limit the present communication 

 wholly to this issue. 



These thirty- six years have been split up into three 

 series of twelve years each, and treated after the manner 



