5/2 



NATURE 



[January 23, 19 13 



not smooth but produced by a large number of irre- 

 j;ular facets, making the curvature quite unfit for 

 optical purposes. In truth it may be fairly taken as 

 established that there is no evidence of any kind to 

 justify us in believing that lenses for optical purposes 

 were ' known or used before the invention of spec- 

 tacles." 



While studying the evolution of fire-getting it 

 occurred to me that this lens might have been used 

 for obtaining fire from the sun ; in other words, as a 

 burning glass. It is well known that when the fires 

 on the ancient altars happened by some accident to 

 go out they had to be renewed by "pure" fire, 

 obtained either by rubbing two sticks together or by 

 concentrating the rays of the sun. 



It would be an interesting investigation to see if 

 this lens could be thus used. Of course, in the dull 

 climate of England it might not work so well as in 

 the sunny latitude of Nimroud, but the experiment 

 would be worth trying, and by noting the extent to 

 which the temperature was raised a good guess might 

 be made as to its efficiency. John Phin. 



Paterson, N.J., U.S..\., December 25, 1912. 



" Primeval Man." 



Your brief review of " Primeval Man " (Nature, 

 January 9, p. 512) devotes rather more than half of 

 its space to the flat contradiction of two statements 

 contained in a footnote. Your reviewer writes : — 

 "That there was no connection between the Druids 

 and the megaliths is absolutely unsupported by 

 evidence. The idea is certainly older than the 

 eighteenth century." 



It is now commonly held that the Druids were an 

 institution peculiar to the Celts, and there is no 

 reason for tracing their origin to the pre-Geltic in- 

 habitants of our islands. As the first wave of Goidelic 

 or Brvthonic invaders cannot have reached Britain 

 much before 600 B.C., a gap of many centuries 

 separates the Druids from the builders of the mega- 

 lithic structures, which, by common consent, belong 

 mainly to the end of the Neolithic or beginning of the 

 Bronze age. 



With regard to the popular notion connecting the 

 Druids with the megaliths, the earliest printed refer- 

 ence appears in the enlarged edition of Camden's 

 " Britannia," 1695. Here seven theories as to the 

 origin of Stonehenge, &c., are cited, and the Druidic 

 tlieory is quoted as being derived from a MS. paper of 

 Aubrev. It is interesting to note in this connection 

 that there is no instance of the words druidic. druid- 

 icaJ, recorded in the" New English Dictionary" before 



1755- 



I am able to take a somewhat impartial view of 

 the objections raised by your reviewer, as the foot- 

 note in question was written for me by the author 

 of. the articles, " Druidism," "Celt," and "'Early 

 Ireland," in the " Encyclopedia Britannica." 



A. HiNGSTON OUIGGIN. 



8S Hnrtington Grove, Cambridge, January 14. 



The origin of the footnote is satisfactorily explained. 

 Sir John Rhvs's papers in the Transactions of the 

 British .'Vcademv are strongly recommended. For 

 l't.-Tii-v information about the British Druids Welsh 

 apH Irish sources should be consulted. The materia! 

 evidence bearing on primeval man, which was omitted 

 from Mrs. Ouiegin's book, is the astronomical testi- 

 monv of the monuments, as interpretative both of 

 Neolithic culture and of the real avocation of the 

 Druid, whose nationalitv or race should be I'egarded 

 as a secondary mailer. Mrs. Ouiggin's Celtic chrono- 



NO. 2256, VOT.. L-)ol 



logy should be revised. Mr. Common Consent, alia^ 

 Commonly Held, is very apt to ignore evidence which 

 he cannot quite follow, and what he follows generally 

 is the angle of least resistance. He is very hard on 

 astronomers and Druids — ancient astronomers. 



Mediaeval \\'Llsh bards speak of bardic prophets as 

 derwvton, modern Welsh derwyddon, "Druids." The 

 traditional regulations for the erection of a stone circle 

 for bardic purposes are prefaced with the statement 

 that the regulations had been handed down from the 

 time of the Welsh princes — that is, before the sub- 

 jugation of Wales by Edward I. (see the section, 

 "Voice of Gorsedd," in Welsh and English, in the 

 printed collection called " lolo MSS.," which may be 

 consulted in most large libraries). Efforts have beei* 

 made to show that such bardic documents ara 

 forgeries, with what motive is not stated. It has been 

 proved, on the other hand, that the "forgers" did not 

 understand their own alleged productions, and that 

 their traducers are still more unaware of the meaning 

 of the architectural principles involved in the tradi- 

 tional account (see Nature for the last twenty years, 

 and the second edition of Sir Norman Lockyer's 

 "Stonehenge"). John Griffith. 



X-rays and Crystals. 



It is not at all difficult to measure the ionisation 

 produced b}' the radiation reflected by crystals, as 

 indeed Prof. Barkia has already suggested. Using 

 a sheet of mica and a pencil of a few millimetres 

 diameter, I find it possible to follow with an ionisation 

 chamber the movement of the reflected spot while 

 the mirror is rotated. W. H Bragg. 



Leeds, January 17 



ANTARCTIC BIOLOGY AND THE ROCKS OF 

 WESTERN WILKES LAND.^ 



THE three last publications on the results of the 

 Antarctic expeditions of the Discovery, 

 Scotia and Gauss show that these works are ap- 

 proaching completion. The new contribution to 

 the scientific results of the Scotia includes all the 

 botanical reports except that on the phytoplankton, 

 which may prove the most important. Of the 

 ten memoirs in this volume, two deal with local- 

 ities, Ascension and Gough Islands (lat. 50° S.), 

 which are outside the Antarctic area; Seven of the 

 memoirs are republished from various journals, 

 while that by Mr. and Mrs. Gipp on the marine 

 algae is a compilation of their three papers with a 

 rediscussion of some of the results. It is a great 

 convenience to have these valuable memoirs col- 

 I lected into one volume; but it is unfortunate that 

 the species founded in them are described in this 

 work as "now species." Much trouble may be 

 thus caused by the annual biological records again 

 cataloguing these species, or by their being sub- 

 sequently assigned to wrong dates. 



' "N.ition.il .\m.irctic Expedition, 1901-4.' Natural History. Vol. vi. 

 "ZooloEV and l!ot,-iny." Pp. .\-vi + g+32 + 63 + plare'; in text. (London : 

 Printed by Order of the Trustees of the British Museum, and sold hy 

 Longmans and Co. : Bernard Quaritch ; Dnlaii and Co., Ltd. ; and at the 

 British Museum (Natural History), 1012.) Price i6.t. 



"Scottish Nation.ll Antarctic Expedition." Report on the .Scientific 

 Results of the Voyage of the S.V. Sc^/in during the vears 1Q02, root,, and 

 1004. Under the leadership of Dr. W. S. Bruce. Vol. iii.. " Botanv." 

 Parts i.-xi. Pp. ix+i53-i-pl!iies in text. (Edinburch : The Scottish 

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 Glasgow : James MacLehose and Sons, 1912.) Price 23.1. 6rf. 



" Deutsche Siidpolar-Expedition, 1901-3." In Auftrage des Reichsamtes 

 des Innern. Herausge^eben von Erich Von Drygalski. ii Band, "Geo- 

 gr-aphie und Geologie." Heft vii. Pp. viii+617-662+2 plates. (Berlin: 

 Georg Reimer, 19-2.) Price 7.50 marks (Subscription price 6.20 marks.) 



