440 



NATURE 



[February 2, 191 1 



I succeeded at once in obtaining it, when the condensed 

 discharge was used. This glow has many interesting 

 properties, of which a preliminary publication seems 

 desirable. 



I believe it to be due to pure nitrogen. Lewis states 

 that it cannot be obtained from atmospheric nitrogen, but 

 this does not agree with my experience. I have used 

 atmospheric nitrogen exclusively. 



The glowing nitrogen is unaffected by silver gauze, 

 which quenches the ozone glows. It is destroyed by 

 mixing oxygen with it, but merely diluted by hydrogen or 

 ordinary nitrogen. When acetylene is led in, a bright 

 flame is produced at the point of confluence. This flame 

 replaces the original glow. It has a spectrum consisting 

 of the swan and cyanogen bands, along with others not 

 identified. If the nitrogen glow is led over iodine a 

 magnificent blue flame is produced, contrasting sharply 

 with the original orange glow. With sulphur the original 

 orange glow is quenched, but no other replaces it. The 

 sulphur becomes hot, and a metallic-looking sublimate is 

 formed along the tube. 



The most remarkable phenomena, however, are with 

 metallic vapours, which give line sjjectra when the glow- 

 ing nitrogen is led over them. Sodium, potassium, 

 thallium, mercury, zinc, cadmium, and magnesium have 

 all j-ielded line spectra in this way. 



Investigation is being pushed on as fast as possiLle, but 

 the facts so far obtained seem to point to the production 

 of a chemically active modification of nitrogen. It is 

 suggested, f)rovisionally, that the spectra are developed by 

 the chemical union of this active nitrogen with the various 

 metals and with iodine and acetylene. The orange glow 

 obtained with nitrogen only would, on this view, be due to 

 the transformation of the hypothetical active nitrogen into 

 ordinary nitrogen. R. J. Strl'TT. 



Imperial College of Science and Technology, 

 January 30. 



Singularities of Curves. 



I HAVE not, at present, access to the books referred to 

 by " T. J. I'a. B." in his letter of January 12; but he 



is altogether wrong in thinking that the singularity he 

 mentions cannot be investigated by the methods explained 

 in my " Geometry of Surfaces." An arbitrary line through 

 the origin has sextactic contact thereat ; but since the axis 

 of X has i2-tactic contact at the origin, the latter cannot 

 be an ordinary sextuple point, because no line through 

 such a point can have a higher contact than septactic. 

 The singularity is either a singular point of the sixth 

 order or one of lower order with coincident branches pass- 

 ing through it, and it illustrates the necessity of drawing 

 a distinction between ordinary multiple points and singular 

 points. The trilinear equation of the curve can be obtained 

 by eliminating t between /3 = ot% a7-;3^ = /8^(iH'''). The 

 factor 07-/3^ suggests the existence of tacnodal or other 

 branches of a similar character, and that the singularity 

 might be transformed into a simpler one lying on a curve 

 of lower degree than the sixteenth by using Cremona's 

 transformation, 



a _ /8 _ 7 



07' + )8''' /ay 7'2 



before applying the methods of chapter iv. of my book. 



But it would have been foreign to the plan of my 

 treatise to have introduced parametric methods when dis- 

 cussing singularities ; moreover, the method of which the 

 example is an illustration is only applicable to unicursal 

 curves, whereas my own methods are independent of the 

 deficiency. For example, the various singularities the 

 point constituents of which are nine nodes could not be 

 investigated by means of a unicursal curve without com- 

 plicating the problem by introducing additional nodes 

 isolated or in combination sufficient in number to reduce 

 the deficiency to zero ; and this might limit the generality 

 of the investigation, for when the nodes exceed a certain 

 number they are not arbitrarily situated, but lie on one or 

 more dianodal curves. A. B. Basset. 



January i^. 



NO. 2153, VOL. 85] 



Mr. Basset now admits that he has seen neither 

 Zeuthen's two papers of 1876 nor Jordan's book of 1893, 

 thus practically acknowledging the accuracy of my 

 criticism — that the treatment of singular points in his 

 " Geometry of Surfaces " is incomplete. With this 

 admission from Mr. Basset the matter ends, so far as 1 

 am personally concerned. 



But I must enter a protest against Mr. Basset's infer- 

 ence that the methods of Zeuthen and Jordan are only 

 applicable to unicursal curves ; since Mr. Basset has not 

 read the work in question, his only reason for this state- 

 ment is the fact that the example in my first letter happens 

 to be a unicursal curve. This example was made up so 

 as to provide a simple illustration of the general methods ; 

 but these methods hold good for curves of any deficiency. 



It is absurd to suggest that parametric methods cannot 

 be used for any algebraic curve ; of course, the coordinates 

 are expressed in the form of infinite series (convergent 

 near a particular point of the curve) instead of terminated 

 series. Mr. Basset's objection to using parametric 

 methods would be quite justified if he had provided us 

 with a satisfactory substitute; but he gives no systematic 

 plan for resolving an assigned singularity, and this is the 

 main object of the parametric method as used by earlier 

 writers. T. J. I'a. B. 



FRANCIS G ALT ON. 



February 16, 1822 — January 17, 191 r. 



'T^riE death of Francis Galton marks, not only the 

 A removal of another link with the leaders of the 

 great scientific movement of the nineteenth century — 

 represented by Darwin, Kelvin, Huxley, Clerk-Max- 

 well, and Galton in this country — but something far 

 more real to those who have been in touch with him up 

 to the last, namely, the cessation of a source of inspira- 

 tion and suggestion which did not flag even to the day 

 of his death. The keynote to Francis Galton 's influence 

 over the science of the last fifty years lies in those 

 words : suggestion and inspiration. He belonged to 

 that small group of inquirers, who do not specialise, 

 but by their wide sympathies and general knowledge 

 demonstrate how science is a real unity, based on the 

 application of a common logic and a common method 

 to the observation and treatment of all phenomena. 

 He broke down the barriers, which the specialist is 

 too apt to erect round his particular field, and intro 

 duced novel processes and new ideas into man\' dark 

 corners of our summary of natural phenomena. 



The present writer remembers being asked some 

 }-ears ago to provide a list of Francis Galton 's chief 

 scientific achievements for use on a public occasion. 

 It did not seem to hiin that a list of isolated contri- 

 butions, such as the establishment of anthropometric 

 laboratories, the introduction of the composite photo- 

 graph, the transfusion experiments to test pangenesis, 

 the meteorological charts and improved nomenclature, 

 the practical reahsation of the possibilities of finger- 

 print identification, the demonstration of the 

 hereditarv transmission of the mental characters rn 

 man, the law of regression, the idea of stirps, or the 

 foundation of the novel science of Eugenics, fully 

 represented the nature of the man. What is the spirit 

 of the contributions — large and small, almost two 

 hundred in number — which Francis Galton made to 

 the science of the last sixty years? ^ The unity of 

 those contributions lay largely in the idea that exact 

 quantitative methods could be applied, nay, rather 

 inust be applied, to many branches of science, which 

 had been held beyond the field of either mathematical 

 or physical treatment. In this manner his inspiration 

 and suggestion tended to give physical and mathe- 

 matical precision to a large number of outlying 

 sciences, to meteorology, to anthropology, to genetics, 



1 His first contribution dates from 1849 and ccncerns a method of 

 printing telegraphic messages at the receiving station. 



