222 



NA TURE 



[July 7, 1892 



conceptual world evolving the perceptive faculty which creates 

 it. An evolution theory which postulates spontaneous genera- 

 tion and human automatonism is natural to the materialist ; and 

 hence our contention that, in spite of the general character of 

 the argument in the earlier chapters of the book, certain con- 

 clusions are distinctly materialistic. 



Again, we are not of those who would bind down all time to 

 Newton's views on matter, force, and motion. That never has 

 been the position of those whom Prof. Pearson delights in 

 nicknaming the Edinburgh school. Only we think a writer 

 should be careful as to what he imputes to Newton. Thomson 

 and Tait say, " We cannot do better, at all events in commenc- 

 ing, than follow Newton somewhat closely " : and unless they 

 have misrepresented the teachingof the " Principia," an attack on 

 their version surely amounts to an attack on Newton. Indeed, 

 Prof. Pearson fully realizes this himself, when, on p. 382, he 

 accuses Newton of thinking of "force in the sense of mediaeval 

 metaphysics as a cause of change in motion." It was this state- 

 ment we took exception to. Similarly, we cannot but look upon 

 Prof. Pearson's obvious jeer at Maxwell's language as of the 

 s ame gratuitous character. 



" Matter is, as it were, the plaything of force" — this evidently 

 Prof. Pearson regards as his trump card. Now these words — 

 and note the "as it were " — occur in the discussion of Newton's 

 laws of motion, and are obviously suggested by Newton's own 

 anthropomorphic language. But they can give rise to no mis- 

 apprehension in the mind of one who is reading Prof Tait's 

 " Properties of Matter" for profit. In the light of the intro- 

 ductory chapter there is really no room for other than wilful 

 misrepresentation of Prof. Tait's position. Moreover, it is 

 positively astonishing to find an author, who has no slender 

 claims to the title of historian, confessing his ignorance of 

 Prof. Tait's lecture on " Force," delivered before the British 

 Association in 1876, and published in Nature, vol. xiv. (see 

 also " Recent Advances," third edition, and Maxwell's " Life," 

 p. 646). That lecture was, we think, the first popular exposition 

 of the subjectivity of force. The recognition of this truth was, 

 of course, a natural consequence of the remarkable series of 

 discoveries which brought home to the mind that energy was 

 physically as objectively real as matter. We certainly did not 

 need to go all the way to Berlin to learn it. C. G. K. 



On the Line Spectra of the Elements. 



I OBSERVE from Prof. Range's last letter that on one point 

 I was led into misinterpreting his meaning by his having used 

 the letter j in his second formula on p. 100 (Nature of 

 June 2) in a sense different from the only definition that had 

 been given of that symbol, viz. the jot of time — the time that 

 light takes to advance one-tenth of a millimetre in the open 

 aether. The period of time represented by/ is as determinate 

 as a day or hour. With it. Prof. Runge's equation represents 

 one definite discontinuous motion along the sloping sides of the 

 teeth of a particular saw, and this is what I understood by it. 

 I perceive now that he intended j to be interpreted in a new 

 sense, and meant the equation to represent uniform motion in a 

 straight line to an indefinite distance. 



If all that Prof. Runge wishes to point out is that motion 

 along an orbit that extends to infinity must be either wholly 

 incapable of being represented by a Fourier's series, or at least 

 must contain a component of that kind, this is both true and 

 obvious ; and the instance he gives (which is, in fact, uniform 

 motion to an unlimited distance along a straight line) is a case 

 in point. But it should be added, no such component of the 

 motion of an electric charge which does not yield to Fourier's 

 theorem can produce any periodic disturbance in the sether : in 

 other words, it would not contribute anything to the spectrum. 

 Accordingly, any such part of the motion — for instance, the 

 advance, in common with the rest of the solar system, of the 

 electrons within the molecules of a gas on the earth, at the 

 rate of eight miles a second, towards the constellation Hercules, 

 which is the precise kind of motion that Prof. Runge adduces 

 as an instance — has nothing whatever to do with the subject of 

 my memoir^ which is an investigation into the cause of double 

 lines in spectra. It should further be added that unlimited 

 motions of any kind have nothing to do with motions going on 

 -within molecules, to the investigation of which chapter iv. of my 

 memoir is devoted, and that any discussion of them there would 

 have been out of place. 



Hence, to represent as a defect which vitiates my reasoning, 



NO. II?^4, VOL. 46] 



as Prof. Runge does, that I have omitted in that chapter to 

 refer to the motions which are not resolvable by Fourier's 

 theorem, is, I submit, not legitimate criticism, especially as the 

 matter, beside being irrelevant, is obvious ; and I also submit 

 that to say " A plausible suggestion about the movement of the 

 molecules ought to explain more than one of the observed 

 phenomena " (Nature, April 28, p. 607) is not criticism 

 at all. We must use the data furnished by our observation of 

 nature to carry us as far as they will go in the interpretation of 

 nature, and not refuse to employ them to that extent because 

 they do not enable us to get further. 



G. Johnstone Stoney. 

 9 Palmerston Park, Dublin, July 2. 



Range of the Sanderling in Winter. 



As my little contribution to the Records of the Australian 

 Museum has been honoured by a notice in Nature [supra, 

 pp. 177-78), I must ask leave to qualify two statements therrin 

 made. Since I wrote it I have become aware that Dr. Finscb 

 had a specimen of the Sanderling {Calidris arenaria) brought 

 to him at Bonham Island, one of the Marshall Group, which 

 lies within the tropics {Ibis, 1880, p. 331) ; and, after the 

 publication of Mr. Everett's list of the birds of Borneo in 

 1889, that gentleman announced the occurrence of this species 

 at Baram, on the north-east coast of that island {Ibis, iSgo, 

 p. 465). Alfred Newton. 



Magdalene College, Cambridge, June 25. 



Immunity of the African Negro from Yellow Fever. 



Dr. Creighton will find that on p. 51 of a report dated 

 1890, " On the Etiology and Prevention of Yellow Fever," Dr. 

 George M. Sternberg (Lieut. -Colonel and Surgeon U.S. 

 Army) makes the following statement : — 



"It has been asserted that the negro race has a congenital 

 immunity from yellow fever, but this is a mistake. The 

 susceptibility of the negro is, however, much less than that of 

 the white race. Amongst those attacked the mortality, as a 

 rule, is small." 



He will also find the subject discussed on pp. 166-67 of " A 

 Contribution to the Natural History of Scarlatina," by Dr. 

 D. Astley Gresswell (Clarendon Press, 1890). Dr. Gresswell 

 writes thus : — 



" The African negro of pure descent was supposed to be 

 insusceptible to the virus of yellow fever and of malaria. It is 

 said, however, that when these affections are prevailing in a 

 virulent form the negro does become infected and mani- 

 fest such infection. This would suggest that the almost 

 complete immunity in the case of the negro has been acquired. 

 Moreover, the fact that negroes of pure descent are more likely 

 to manifest the symptoms of yellow fever on exposure to the poison 

 after they have passed some years or some generations in more 

 temperate latitudes, in which the disease is not indigenous 

 suggests that in order to maintain this degree of immunity it is 

 necessary that the negro should continue to live in localities in 

 which the virus exists ; in other words, that the individual or 

 the race should be repeatedly subjected to the virus. It may, 

 in fact, be questioned how far, in regard to these diseases in 

 man, susceptibility differs independently of protection acquired 

 by previous subjection to the action of the virus or its products ; 

 though natural selection may (as certain facts indicate) have 

 acted more directly. Indeed, it is quite possible that protection 

 acquired by previous infection is much more frequently a cause 

 for benignity or only partial susceptibility in the case of these 

 and other infection-diseases than is generally allowed for." 



I do not think I can with advantage add anything to these 

 quotations. Your Reviewer. 



A Solar Halo. 



In connection with the heavy thunderstorms further south, 

 possibly, there was here the most brilliant solar halo on the 

 29th which I have seen. The wind was easterly all the time, 

 causing sea-fog-like clouds in the morning, which dissipated 

 by degrees about 10, but I did not notice the halo before 10.45, 

 nor after 3.30 or 4 o'clock. It was certainly gone at 5. 



Though a complete halo at 11, it was far intenser above and 

 below, the north-west and south-east octant especially. By i 

 o'clock this had shifted to the north-east and south-west octants. 



