March 31, 1921] 



NATURE 



141 



tection. We may now doubt whether they do, at any 

 rate in some circumstances. 



In the interests, therefore, not only of radiologists, 

 but also of suffering humanity which any curtailment 

 of the facilities for X-ray treatment will affect, I 

 itppeal for an organised effort on the part of physicists 

 and biologists in collaboration to institute research 

 into the effect of X-rays on living tissues. I have 

 sufficient confidence in science to feel that, as a 

 result, methods will be devised which, while pre- 

 serving the usefulness of the rays for medical pur- 

 poses, will guard the devoted band of practitioners 

 against the tragic risk which now stands revealed. 

 I feel that in making this appeal I am discharging 

 a duty imposed upon me by my brother. 



March 25. 



Since the above was written I have learned 

 that some months ago steps were taken by the 

 Medical Research Council to organise research 

 on the action of radio-active rays on living tissues. 

 With this work prominent physicists will be asso- 

 ciated. I am confident that this collaboration will be 

 productive of good results, and I am glad to know 

 that the appeal I ventured to make had already been 

 answered. A. B. Bruce. 



March 29. 



Greenland in Europe. 



During the present month a new light has been 

 thrown upon the Aberdeen kayak (skin-canoe) referred 

 to in Nature of January 13, p. 648. Fresh informa- 

 tion upon this subject is found in a diary of a tour 

 through Scotland in 1760 by the Rev. Francis Gastrell 

 (born 1707; M.A. Oxon. 1728), son of a Bishop of 

 Chester, and owner — by purchase in 1753 — of New 

 Place, Stratford-on-Avon. His diary is now pre- 

 served in the Shakespeare Museum at Stratford. In 

 a paper read on March 10 before the Edinburgh 

 Bibliographical Society Mr. James Sinton quoted 

 Gastrell 's statement that when visiting King's College 

 Chapel, Old Aberdeen, on October 12, 1760, he there 

 saw " a Canoo about seven yards long by two feet 

 wide whfich] about thirty-two years since was driven 

 into the Don with a man in it who was all over hairy 

 & spoke a language whfich] no person there could 

 interpret ; he lived but three days, tho all possible care 

 was taken to recover him." This canoe is now in 

 the anthropological museum at Marischal College, 

 -Aberdeen. Its exact length is 17 ft. q in., its greatest 

 breadth being scarcelv 18 in. and its weight 34 lb. 

 Francis Douglas, who saw it in or about the year 

 1782, describes it as "a canoe taken at sea, with an 

 Indian man in it, about the beginnin.<^ of this cen- 

 tury. He was brought alive to Aberdeen, but died 

 soon after his arrival, and could give no account of 

 himscjlf." 



These two statements do not coincide, but there can 

 be little doubt that they relate to the same individual. 

 The hairiness of which Gastrell speaks suggests a 

 non-Mongolian type, but it might onlv mean an imper- 

 fect recollection of the fur hood, shirt, and breeches 

 worn by kayak-men. A similar canoe, captured in 

 Orknev waters, and preserved in Edinburgh in i6q6, 

 had with it " the shirt of the barbarous man that was 

 in the boat." Dr. James Wallace (F.R.S. Lond.}, 

 writing in 1700, savs that " there is another of their 

 boats in the Church of Burra in Orkney." In the 

 same year the Rev. John Brand states that such 

 canoes and canoe-men were then frequently seen up>on 

 the coasts of Orknev, " as one about a year ago on 

 Stronsay, and another within these few months on 

 Westray — a f*pntleman with many others in the Isle 



NO. 2683, VOL. 107] 



looking on him nigh to the shore, — but when 

 any endeavour to apprehend them they flee away 

 most swiftly." David MacRitchie. 



4 Archibald Place, Edinburgh, March 21. 



The Peltier Effect and Low-temperature Research. 



With further reference to the suggestions of Mr. 

 Campbell Swinton and Sir Oliver Lodge contained in 

 Nature of March 10 and 17 that the Peltier effect 

 may disappear at a very low temperature, this appears 

 very improbable from the fact that, as long ago 

 pointed out by myself, there is a continuous transi- 

 tion between metals and non-metals, and this dis- 

 tinction between them does not vanish at low tem- 

 fHjratures. Consequently, pairs of elements must 

 always exist with electrothermic differences. The 

 nearly "perfect" metal may become a "perfect" 

 conductor of heat and electricity, and the nearly 

 "perfect" non-metal may become a " peftfect " non- 

 conductor at low enough temperatures, but the inter- 

 mediately graded elements would become neither 

 perfect conductors nor absolute non-conductors, but 

 would behave much like certain elements at ordinary 

 temperatures. The periodic law would enable 

 physicists to predict almost with certainty which 

 elements would exhibit the desired effect best at low 

 temperatures. . 



It may repay physicists who intend to study these 

 effects to look up papers written by me many years 

 ^Ro, e.g. " Some Remarks on the Connection between 

 Metals and Non-Metals," etc., which occur in the 

 Chemical News during the years 1903, 1904, and 1905. 

 Also my book " Researches on the Affinities of the 

 Elements and on the Causes of the Chemical Simi- 

 larity of Elements and Compounds " (1905). I have 

 been hoping for the opportunity of revising the latter 

 and bringing it up to date, but unfortunately have 

 always been overwhelmed with technical work. 



Geoffrey Martin, 



109 Corporation Street, Manchester, 

 March 22. 



Relativity and the Velocity of Light. 



The great interest of Mr. Jeans's letter on this 

 subject in Nature of March 10 is, I think, sufficient 

 justification for my letter by which it was evoked. 



The argument used bv Mr. Jeans to support the 

 proposition that it can be shown that both on the 

 outward and on the inward journey light travels with 

 the same constant velocity is, to me, difficult to follow. 

 Majorana's experiments deal respectively with a 

 source and a reflecting mirror moving relatively to 

 the observer, whereas in the Michelson-Morley experi- 

 ment both are at rest with the observer. I cannot 

 then see the bearing of Majorana's results upon the 

 question whether P and a remain unchanged in the 

 case given by Mr. Jeans. 



I am sorry I misunderstood the words used by Mr. 

 Jeans in his article in Nature of February 17 to 

 imply a belief in the possibility of measuring the 

 velocity of light in a unidirectional course. It appears 

 to me, however, that the truth of this proposition is 

 involved in the affirmation of the proposition referred 

 to in the paragraph above; for the mean velocity of 

 light on its outward and return journeys after reflec- 

 tion from a mirror can be measured. If also its con- 

 stancy outwardly and inwardly can be affirmed, does 

 it not follow that the velocity on a unidirectional 

 course becomes known, contrary to the principle of 

 relativity? C. O. Bartrum. 



32 Willoughby Road, Hampstead, March 15. 



