April 25, 1872] 



NATURE 



499 



The Higher Ministry of Nature : viewed in the Light of 

 Modern Seieiiee, and as an Aid to Advanced Christian 

 Philosopliy. By John R. Leifchild. (London : Hodder 

 and Stoughton, 1872.) 

 Mr. Leifchild is already known as a careful writer on 

 matters connected with economic geology ; he now appears 

 before the public in the avowed character of ambassador 

 between the opposing forces of Theology and Science. 

 This bulky volume of upwards of 500 pages appears to be a 

 kind of commonplace-book of thoughts which have occurred 

 to him in solitary wanderings ; the title means to express 

 that the author concerns himself with subjects higher than 

 those which "subserve our present individual and collec- 

 tive interests." We must acknowledge that works of this 

 kind, endeavouring to reconcile in detail the conflicting 

 theories of theologians and men of science, are little to 

 our taste ; we suppose, however, they have their public ; 

 and in the case of the volume before us, the large type, 

 wide margins, and handsome binding, are all in its favour. 

 With this preliminary objection, that portion of Mr. Leif- 

 child's work which comes within our scope — for the greater 

 part does not — seems treated with considerable care and 

 knowledge, and with a higher degree of impartiality than 

 is usually to be met with in such works. The Darwinian 

 doctrines of evolution and natural selection of course 

 come in for some severe criticism ; we are surprised that 

 Mr. Leifchild should reiterate the superficial and often re- 

 futed objection that geology has not yet revealed a single 

 fossil /;/ transitu from one species to another, as if it were 

 possible that geology should reveal anything but the suc- 

 cessive connecting and connected links, which it has done, 

 and is doing every day. Those who delight in specula- 

 tions on the border-land between the natural and the 

 supernatural will find much to interest them in the 

 volume, and to such we commend it. 



LETTERS TO THE EDITOR 



[ T/ic Editor does not hold himself responsible for opinions expressed 

 by ills eorrespondents. No notice is taken of anonymous 

 communications. ] 



Spectroscopic Nomenclature 

 Your columns were not long since opened to a discussion, 

 rather long drawn out, on a point of nomenclatuie. Tliey are 

 now, as ever, open to all reasonable discussion on that most in- 

 teresting aspect of Nature presented by the spectroscope. I 

 cannot help thinking that some advance might be made if the 

 facul ties exhibited in the one were now brought to bear on the 

 othe.. There seems to be a lamentable tendency in zealous but 

 disorderly minds to pay as little attention as possible to those 

 aids to reasoning — those signs of ideas, which ought to be cur- 

 rent coin. 



I do not in the least propose to myself to attempt to mount 

 the breach just now. But I would fain challenge attention, and 

 urge a fair amount of consideration, on some few points in which 

 I have noticed very diverse methods of expressing the same thing. 

 And in so doing I may find it necessary to give my voice in 

 favour of one or the other. But it is not my object to advocate 

 so much as to indicate. 



Observations have recently been made of the sun during 

 eclipse of a kind which, if not so novel as some think, is in- 

 tensely interesting, and must be constantly referred to, I mean 

 with a free prism. Now it occurs to me that it would be easy 

 to reserve the spectroscope for that instrument which we have 

 been accustomed to call such and to characterise these other 

 observations as prismatic, as distinct from spectroscopic. It would 

 then be known at the very outset that there was no slit. This 

 would not prevent a juvenile disciple of Newton from repeating his 

 prismatic examination of a chink, and getting his linear spectrum ; 

 it would only keep before him the origin and constitution of that 

 spectnim in a way which the sole use of the spectroscope appears 

 not to do. The prismatic and the spectroscopic methods of ex- 

 amining a luminous object are totally distinct. Thus the Poodo- 

 cottah observations were of one kind, those at Dodabetta of the 



other ; those at Bekul, of both. It is of no consequence, for 

 this matter, where the prism is, it is the absence of the slit that 

 makes the difference. Thus, for the purpose of illustration, I 

 may allude to the planetary nebula seen prismatically unaffected 

 in the midst of a star cluster turned into streaks. And the 

 prominences seen in an open slit are to all intents seen prismati- 

 cally. It is obvious that there is here a distinction of idea which 

 may be advantageously fixed by a distinctive use of words. Let 

 the spectroscope mind its o^vn business, which is to make and 

 examine linear spectra. The moment it ceases to do so it ceases 

 to be a spectroscope. 



This brings me to the next point. Since the prism does not 

 require a slit, — on the contr.iry, is a very valuable tool, as we have 

 seen, without, — it ought never to see lines, except as it sees other 

 forms, i.e., out lines. There is a confusion of ideas — rather, I 

 should say, a contraction of ideas — in setting a prism to look 

 for lines. It is the spectroscope which sees lines, the prism sees 

 images, forms. It is an accident of the case if the form happens 

 in any of its parts to be at the same time linear, and having its 

 linear portion in a certain direction. Thus, when in a prismatic 

 examination of the solar crescent immediately before eclipse, the 

 cusps become linear — albeit curvilinear — there is a failure of 

 grasp in speaking of the dark cusp-images as dark lines ; or, 

 at any rate, there is an opportunity lost of exemplifying the 

 principle which pervades the whole of the phenomenon, and of 

 fixing the prismatic idea. 



The same kind of misuse of terms I have had occasion to 

 point out on the occasion of the first prismatic examination of 

 an eclipse, when what are now called, happily, zones, were un- 

 happily and mistakenly called by the technical term " bands." 



I now pass on to the confusion whicli exists in the nomencla- 

 ture of lines. The subject fully treated would embrace the 

 whole range of spectral analysis ; but I must confine what I 

 have to say to solar spectra. 



In the early days of solar examination with the spectroscope, 

 I made my venture, in the direction which I am now pursuing, 

 and it failed. Ignorant that I was already distanced — no matter 

 how or why — I suggested certain symbols for certain lines, fore- 

 seeing somewhat of what has come to pass. Aiming to avoid 

 an affiliation which further knowledge might prove false, but 

 admitting the great probability that the lines at C, F, 2796 (K) 

 were really due to hydrogen, I would have called these solar 

 bright lines a, f3, y, the hydrogen lines being already known as 

 Ho, H/3, II7 ; that which is now variously called "D.,," "D^," 

 "near D," or sometimes plain "D," I would have had known, 

 in the same category, as 5. And other Greek letters expressed, and 

 would have sufficed to express, as many more as the memory 

 would require to hold. The venture failed, as I say ; and con- 

 sidering that no little confusion has resulted, I cannot help 

 thinking it a pity that it did. Soon after appeared a work on 

 spectrum analysis, in which H7 is ignored, and the bright 

 solar line which corresponds with 2796 (K) and with Hy is per- 

 sistently called and identified with G, to the great scandal of the 

 ghost of Fraunhofer and (I doubt not) the living Thicker. The 

 blunder has often been repeated since, indeed I have seen it in 

 Nature more than once in the last few days. If it was not to 

 have a Greek letter, at least it had a better right to be known as 

 "2796 (K) " than has the coronal line to be called " 1474 (K). " 

 Failing that, it has been paraphrased, the shortest form being 

 " near G-" Surely it is time this were put right. 



And now we have "1474." No one knows what the true 

 position of that line is. The line 1474 (K) is an iron line, and it 

 is to the last degree improbable that the coronal line is identical 

 with it. The misnomer has carried with it, naturally, the idea 

 that the source is iron. As this is an improbability of a higher 

 order still — because there is evidence against it in the absence of 

 a few hundred other iron lines — a false idea is in process of being 

 fixed. 



And all this arises, and much more will follow, from the lazi- 

 ness of mind, if I may so call it without offence, which adopts 

 a name belonging to something already, instead of first reserving 

 judgment, and giving it an independent standing with a name of 

 its own. 



■Then there is the confusion of idea, and uncertainty in under- 

 standing exactly what is intended in speaking of the extension of 

 the spectrum, and of position in it, as right and left, or left and 

 right, as the case may be ; or the confusion is avoided by the 

 precise but cumbersome reference to degree of refrangibility, 

 This is quite unnecessary. This is so exact an analogy between 

 the degree of refrangibility and the degree of heat that no one 



