185 



be made respecting the proneness or not of the Australian 

 aborigines to vary individually as compared with more 

 mixed or less purely bred races. Prof. Pearson and his col- 

 leagues in the Philosophical Transactions of the Royal So- 

 ciety, London, have, during the past few years, published 

 Contributions to the Mathematical Theory of Evolu- 

 tion, showing how variation may be exhibited by mathemati- 

 cal formulae and curves, such curves arising in many physical, 

 economic, and biological investigations, as, for instance, 

 various types of anthropological measurements. They say, 

 "if measurements be made of the part or organ in several 

 hundred or thousand specimens of the same type or family, 

 and a curve be constructed of which the abscissa x represents 

 the size of the organ, and the ordinate y the number of 

 specimens falling within a definite small range, d x of organ, 

 this curve may be termed a frequency curve. The centre or 

 •origin for measurement of the organ may be taken as the 

 mean of all the specimens measured. In most cases, as in the 

 case of errors of observation, they have a fairly definite symme- 

 trical shape, and one that approaches with a close degree of ap- 

 proximation to the well known error or probability-curve. 

 A frequency-curve, which for practical purposes can be re- 

 presented by the error-curve, will be termed a normal-curve. 

 When a series of measurements give rise to a normal-curve, 

 we may probably assume something approaching a stable 

 condition; there is production and destruction impartially 

 round the mean. In the case of certain biological, sociologi- 

 cal, and economic measurements there is, however, a well- 

 marked deviation from the normal shape, and it becomes im- 

 portant to determine the direction and amount of such devia- 

 tion." The more data and the greater the number of in- 

 dividual observations there are, the more correct would be 

 any such comparative measurements, and we may confidently 

 expect that the projected extended anthropological investiga- 

 tions of Prof. Spencer and Mr. Grillen will add greatly to the 

 already accumulated store. The presumption is that such 

 an enquiry would show that the curve would approach more 

 nearly a normal-curve in so pure a type as the Australian 

 aborigines than in the more mixed European races. 



