Aprn 50, 18S5] 



X. IT LIRE 



60 ' 



against." Evidence is always cropping up that the author 

 is in the habit of going farther into a subject by original 

 mathematical analysis than by reading up other people's 

 work. I will give some examples. Speaking of a refer- 

 ence by Rankine to cubic asymmetry, he says : — " 1 only 

 came across this in Rankine two or three days ago. But 

 I remember going through the same thing myself' not 

 long ago, and I said to Stokes — I always consulted m\ 

 great authority, Stokes, whenever 1 got a chance — ' Surely 

 there may be such a thing found to exemplify this kind 

 of Hsymmetryj would it not be likely to be found in 

 crystals of the cubic class?' Stokes— he knew almost 

 everything — instantly said : ' Oh, Sir David Brewster 

 thought he had found it in cubic crystals, but there was 

 an explanation that it seemed to be owing to the effect 

 of the cleavage planes or the separation of the crystal into 

 several crystalline laminae" 1 (p. 158). Then again he 

 : — " 1 am ashamed to say that I never heard of 

 anomalous dispersion until after I found it lurking in the 

 formulas. I said to myself, ' These formulas would imply 

 that, and I never heard of it :' and when I looked into the 

 matter I found, to my shame, that a thing which had 

 been known by others for eight or ten years I had not 

 known until 1 found it in the dynamics " (p. 120). Once 

 more we find : — " I was thinking about this, three days 

 ago, and said to myself, ' There must be bright lines of 

 reflection from bodies in which we have those molecules 

 that can produce intense absorption. Speaking about it 

 to Lord Rayleigh at breakfast, he informed me of this 

 paper of Stokes's, and I looked and saw that what I had 

 jilt of was there. It was known perfectly well, but 

 the molecule first discovered it to me. I am exceedingly 

 interested about these things, since I am only beginning 

 to find out what everybody else knew, such as anomalous 

 dispersion, and those quasi colours, and so on " (p. 2S2). 



The purely physical bent of the author's reasoning is 

 well shown in speaking of Rankine's work at p. 270 : " I 

 do not think I would like to suggest that Rankine's mole- 

 cular hypothesis is of very great importance. The title is 

 of more importance than anything else in the work. Ran- 

 kine was that kind of genius that his names were of 

 enormous suggestiveness, but we cannot say that always 

 of the substance. We cannot find a foundation for a great 

 deal of his mathematical writings, and there is no explana- 

 tion of his kind of matter. I never satisfy myself until I 

 can make a mechanical model of a thing. If I can make 

 a mechanical model, I can understand it. As long as I 

 cannot make a mechanical model all the way through, I 

 cannot understand ; and that is why I cannot get ' the 

 electromagnetic theory. I firmly believe in an electro- 

 magnetic theory of light, and that, when we understand 

 electricity and magnetism and light, we shall see them all 

 together as part of a whole. But i want to understand 

 light as well as I can without introducing things that we 

 understand even less of. That is why I take plain 

 dynamics. I can get a model in plain dynamics, I cannot 

 in electromagnetics. But so soon as we have rotators to 

 take the part of magnets and something imponderable to 

 take the part of magnetism, and realise by experiment 

 Maxwell's beautiful ideas of electric displacements, and 

 so on, then we shall see electricity, magnetism, and light 

 closely united and grounded in the same system." 



The model of an electromagnetic ether described by 

 Prof. Fitzgerald on March 28 to the Physical Society, 

 founded on Clerk Maxwell's celebrated papers in the 

 "Philosophical Magazine in 1S60 and 1861, goes a long 

 way to clear away the objection raised by Sir William 

 Thomson. 



In reading these lectures, it must be remembered that 

 they are uncorrected verbatim reports, and one is sur- 

 prised at seeing that the matter is so continuous and 

 readable. A considerable freshness is given by the con- 



1 These reports are generally quite verbatim, but I am sure Sir William 

 Thomson is not responsible for this chai 



versational interludes and remarks, which would not per- 

 haps have appeared in a written work. As mentioned 

 before, Sir William spo'ie of the pressural wave as an 

 animal ; this was very happy, as he had just before- called 

 it the bete noir of the mathematicians. He says at p. 

 34 : — " I do not like the words ' paradoxical phenomenon.' 

 'Curious phenomenon' or 'interesting phenomenon' 

 would be better. There is no parade : in science. We 

 may .all it a dynamox, but not a paradox" At p. 115 

 he says: — The struggle of 1815 (that is not the same 

 idea as i , -. who was to rule 



the waves, Cauchy or Poisson ? " 



To many it will seem, after reading these lectures con- 

 taining a review of what has been done and suggestions 

 of what might be done, that certain facts are hopelessly 

 irreconcilable with the wave-theory of light. Sir William 

 Thomson has certainly not shirked a single difficulty, and 

 -perhaps has even made them look more glaring than is 

 necessary. But, if this be an error, it is on the right 

 side. 



The reporter has introduced into the volume some 

 doggerel rhymes read by a certain student of the lectures 

 at a farewell dinner at Baltimore given by President 

 Oilman : — 



The Lament of the Twenty-one Cth'/fhn m at parting from 

 each other and from <V Molecule 



'tropic molecule was looking at the view, 

 Surrounded by his coefficients twenty-one or two, 

 And wondering whether he could make a sky of azure 1 lue, 

 With plagiotatic a b c and thlipsinomic Q. 



They looked like sand upon the shore with waves upon the sea, 

 But the waves were all too wilful and determined to be- free ; 

 And in spite of n's rigidity they never could agree 

 In becoming quite subservient to thlipsinomic P. 

 Then web-like coefficients and a loaded molecule, 

 With a noble wiggler at their head, worked hard as Haughton's 



mule ; 

 But the waves all laughed, and said, "A . iggler, thinking he 



could rule 

 A wave, was nothing better than a sidel lormal fool." 



So the coefficients sighed, and gave a last tangential skew, 



, and .S and 7' and I ', 

 And with a tear they parted ; but they said they would be true 

 To their much-beloved wiggler and to thlipsinomic Q. 



Signed, (f, f), a Cross Coefficie.. fctMJUJ led 



The social and scientific intercourse of these three 

 weeks at Baltimore was an experience that will be for- 

 gotten by none of the twenty-one coefficients, and they 

 all sympathised with Sir William Thomson in his con- 

 cluding remarks at p. 289 : — 



" I am exceedingly sorry that our twenty-one coefficients 

 are to be scattered, but, though scattered far and wide, I 

 hope we will still be coefficients working together for the 

 great cause we are all so much interested in. I would be 

 most happy to look forward to another conference, and 

 the one damper to that happiness is that this one is now 

 to end, and we shall be compelled to look forward for a 

 time. I hope only that we shall all meet again in some 

 such way. I would say to those whose homes are on this 

 side of the Atlantic, ' Come on the other side and I will 

 welcome you heartily, and we may have more confer- 

 ences.' Whether we have such a conference on this side 

 or on the other side of the Atlantic again it will be a 

 thing to look forward to — as this is to look back upon — 

 as one of the most precious incidents I can possibly have. 

 I suppose we must say farewell ! " Oeorge Forbes 



THE SEMAPHORE AND ELECTRIC LIGHT 

 AT SHANGHAI 



THE European and American community occupying 

 the so-called foreign concessions in Shanghai has 

 lately adopted the electric light. 'I he illustration given 



