584 



NATURE 



[July 8, 1920 



will be published before the great interest which 

 has been aroused by the present foretaste has 

 •evaporated. 



The most interesting- points brought out in the 

 present book are those which serve to throw 

 partial light on the great stone statues which are 

 so abundant in the island, and, in connection 

 with these, on the origin of the Piaster Island 

 folk. It has hitherto generally been assumed 

 that these folk were of Polynesian race. But 

 recent research, by Prof. Keith and others, seems 



Fig. 2. — A finished Hat at Ahu Hanga O Ornu ; others in the distance. From " The Mystery 

 of Easter Island," 



to show that, in Easter Island, as in so many 

 of thfe South Sea Islands, several races with 

 other than Polynesian culture have from time 

 to time invaded this remote and isolated islet. 

 Mr. Henry Balfour (in Folklore for December, 

 1917) has suggested (modestly he disclaims to 

 have done more) some of the main results to 

 which Mr. and Mrs. Routledge's experiences 

 seem to point, and chiefly to the probability that 

 at some long-distant time a strong wave of 

 Melanesian influence reached Easter Island. 

 Certain points of curiously strong resemblance 



between Easter Island arts and customs and 

 those found m certain of the Solomon Islands 

 serve to illustrate this. 



Without throwing any doubt on this sugges- 

 tion, tentatively put forward by Mr. and Mrs. 

 Routledge, with the strong support of Mr. Balfour 

 and others, I again venture to put forward 

 the view that, while Easter Island cul- 

 ture is doubtless of very mixed origin, Poly- 

 nesian and Melanesian elements being most 

 strongly represented, there were probably also 

 other element.s — e.^. some -influence, 

 possibly slight, and only very occa- 

 sional, from the not far distant 

 American shore lying to the east- 

 ward. Eor instance, the script (on 

 wooden plaques), the rock-carvings, 

 the featherwork, and the very pecu- 

 liar form of tapa (bark cloth) which 

 was used in Easter Island, all seem 

 to me to suggest an Eastern, rather 

 than a Western, origin. 



One other suggestion may here be 

 put forward as a contribution to the 

 consideration of the Easter Island 

 mystery. Mrs. Routledge writes of 

 the well-known " top-pieces " which 

 are, or were, superimposed on the 

 statues as "hats"; and Mr. Balfour 

 suggests that these were very prob- 

 ably meant to represent not hats, 

 but hair, and in the number of Folk- 

 lore above quoted he works this out 

 in very ingenious detail. I venture to 

 suggest a slight amendment to Mr. 

 Balfour's proposition — i.e. that the stone cap- 

 pieces in question were meant to represent not 

 actual growing human hair, but wigs, such as 

 those which were, and still to some extent are, 

 commonly used by Fijians — though whether by 

 those of Polynesian or Melanesian origin I cannot 

 now say. It would be interesting to know how far 

 such wigs were used in other parts of the Paciflc. 

 It is satisfactory to know that a second edition 

 of Mrs. Routledge's book is already in course of 

 preparation, and all ethnologists must hope that 

 the full scientific data will also soon be published. 



The Blue Sky and the Optical Properties of Air.^ 

 Bv the Right Hon. Lord Ravleigh, F.R.S. 



Scattering by Small Particles. Polarisation. 



nPHE subject chosen for this evening is one 

 ^ which specially interested my father through- 

 out his career. I shall try to put before you some 

 of his conclusions, and then pass on to more 

 recent developments, in which I have myself had 

 a share. 



Let us begin with one of his experiments which 

 illustrates the accepted theory of the blue sky. 



1 Discourse delivered at the Royal Institution on Friday, May 7, jgac. 



NO. 2645, ^OL. 105] 



We have here a glass tank containing a dilute 

 solution of sodium thiosulphate. A condensed 

 beam from the electric arc traverses it and then 

 falls on a white screen, where it shows the usual 

 white colour. I now add a small quantity of acid, 

 which decomposes the solution with slow precipita- 

 tion of very finely divided particles of sulphur. 

 As soo« as this precipitation begins you see that 

 light is scattered — that is to say, it is diverted 

 to every side out of the original direction of pro- 

 pagation. Moreover, you will observe that the 



