July 26, 1877] 



NA TURE 



251 



A REMARKABLE DEFORMITY OF THE 

 TEETH AMONG THE INHABITANTS OF 

 THE ADMIRALTY ISLES'- 



'T'HE Russian traveller, M. Miklucho-Maclay, in the 



-'• course of recent travel in Melanesia, has noticed 



among the natives of the Admiralty and Hermit Isles a 



remarkable peculiarity in the teeth, the upper incisors 



projecting " shovel like," almost horizontally, and to such 

 a degree as to extend even beyond the lips when the 

 mouth is closed. The breadth, moreover, of one of these 



tee'h is at times so great as to equal its visible length ; 

 being in the specimen figured as much as 19 millimetres 



* See a note contributed to the lUiistrh-ti: Zcitintg of Leipzig by M. 

 Mikluclio-Maclay. 



to 16 mm. of length, measured, of course, from the edge 

 of the jaws, not from the extremity of its fang. As all 

 the teeth have a blackish polish, due to the prevailing 

 habit of betel-chewing, the mouth presents a somewhat 

 ghastly appearance. M. Miklucho-Maclay has nowhere 

 else met with a similar deformity of the teeth, but heard 

 of such, when on the peninsula of Malacca, the race in 

 which It occurs being called " orang-gargassi." ' 



J. C. G. 



RAINFALL AND SUN-SPOTS 



A'XrE have received the following communications 

 *» having reference to Gen. Strachey's paper on the 

 above subject, which we printed some little time back. 



The conclusions of Mr. Meldrum as to a relation 

 between the amount of rainfall and the frequency 

 of sun-spots have become a subject of much interest 

 with reference to the possibility of being prepared (o: 

 such a deficiency of rain in India as may result in a 

 failure of crops and consequent famine. That the vary- 

 ing yearly rainfall at Madras showed on the whole a 

 rather marked agreement with the sun-spot period, has 

 been known to me for some time, and Dr. Hunter has 

 lately made an examination of the amounts relatively to 

 an eleven-yearly cycle which has excited marked attention 

 on account of its possible practical application. Gen. 

 Strachey has made a discussion of the Madras observa- 

 tions in a paper read before the Royal Society, a full 

 abstract of which has appeared in Nature (io\. xvi., 

 p. 171). He has sought to show that there is no evidence 

 in the Madras observations of periodicity at all ; and 

 that if the rainfalls for each of the sixty-four years were 

 written on slips of paper and drawn from a bag, so that 

 the first amount drawn should be placed to the first year 

 (18 1 3), the second to the next year (1814), .-md so on, as 

 well-marked a result would be obtained as is shown by 

 the quantities observed in their respective years. This 

 conclusion he founds on the following method, which he 

 terms a " true criterion of periodicity." 



If the differences of the rainfall for each year from the 

 mean of the whole sixty-four years be taken, and the 

 mean of all these differences (without respect to sign) be 

 called the general mean difference ; if we arrange the 

 yearly rainfalls in horizontal series of eleven successive 

 years (there will be six such series nearly), and the 

 means for the first, second .... years of the series be 

 taken, these quantities (periodic means) will show the 

 mean variation in the period of eleven years, if any such 

 exist. If now the differences of the yearly rainfalls from 

 the periodic means for the corresponding years be 

 obtained, the means of these, irrespective of sign, may be 

 called ihe periodic mea.n differences. In the case of the 

 Madras rainfalls Gen. Strachey finds^ 



The ^'<'««v7/ mean difference = I2'4 inches, 

 The periodic ,, ,, = II'2 ,, 



and his true criterion of periodicity, though not so 

 definitely stated as might be wished when so important 

 a rule is proposed, appears to be that if there be no 

 periodicity the variation in the periodic means will tend 

 to disappear in a sufficiently long series of observations 

 and the general and periodic mean differences be iden- 

 tical. It seems to me that the disappearance of a varia- 

 tion in the periodic means is here the true criterion of 

 no-periodicity ; but though a very large variation exists 

 in the case of the Madras observations, yet Gen. Strachey 

 concludes that since the periodic and general mean 

 differences agree so nearly, there is no tendency to 

 periodicity shown in the Madras observations. 



As an illustration of the true criterion, Gen. Strachey 



^ Man-devil. Orang\% the usual Malay word for nun, while gar^asn is 

 equivalent to the German QuAlgeist, tormenting spirit. — J. C. G. 



