FEa 3, 1882.] 



KNOWLEDGE 



287 



value (three of the most important observations by this 

 method were made by him), he has done most valuable 

 work outside this particular line of research. He was one 

 of those who first demonstrated the gaseity of the solar 

 corona ; he tirst demonstrated the existence of the atmo- 

 sphere of multitudinous gases existing close to the visible 

 solar surface ; we owe to him the recognition of nine-tenths 

 of the lines of the solar sierra (all of those lines which 

 were at all difficult to discover) ; and he invented the 

 method (successfully applied by Respighi and Lockyer in 

 1S71) of observing the corona with a slitless spectro- 

 scope ; these, and a number of other researches, more than 

 justify what I said last fortnight. It appears to me — I 

 speak under correction — that a rival worker in the same 

 iield, like the editor of Xature, one who formerly held 

 views opposed to those which Professor Youngs original 

 researches have established, should not have allowed the 

 above-quoted paragraph to appear in the journal which, we 

 must assume, he controls. Some critics might attribute 

 the review to his pen, and point out that while science 

 must always gain, both in progress and Ln tone, from emu- 

 lation amongst scientific fellow-workers, the same cannot 

 be said of the quality which is associated with " malice 

 and all uncharitableness," and in reference to which the 

 old proverb says that Qui invidet minor est. We must not 

 suppose, however, that the renew was written by the editor 

 of Xature. 



In this, my second notice, promised in the last 

 number but one, I propose to touch on some of 

 the remaining subjects admirably dealt with by Pro- 

 fessor Young, and to show that the sole subject worth 

 referring to is not, as the reviewer in Nature seems to 

 think, that investigation of the nature of the elements, in 

 which Mr. Lockyer is understood to have been engaged (as 

 that re\-iewer, indeed, asserts) during the last thirteen 

 years,- — with important results hereafter, we may suppose, 

 to be made more fully knoi^iu (The communications to 

 the Eoyal Society in 1878 and 1879 are understood to be 

 merely preliminary.) 



In the first place, there is an admirable account of the 

 solar spots and faculw, with absolutely the best description 

 we have yet seen of the various stages of the growth and 

 development of the larger spots. The discussion of the 

 proper motion of the spots, and of the theories which have 

 been advanced in explanation of the seemingly more rapid 

 rotation of the equatorial regions is admirable. Here, 

 though the subject does not require any difficult mathe- 

 matical discussion, Professor Young's familiarity -n-ith 

 mathematical methods of reasoning stands him in good 

 stead. We may note, in passing, that Professor Young 

 has not allowed his book to be disfigured by that ridi- 

 culous picture illustrating (save the mark !) the sun's 

 axial inclination, which first appeared, we beKeve, in 

 Guillemin's " Heavens," and has since done duty in so 

 many astronomical works (by writers who should assuredlv 

 know better, and doubtless do). We could have wished 

 he had substituted another, but it is certainly better to 

 have no picture at all than to admit one conveying quite 

 erroneous ideas. 



Passing to the portions of the sun outside the photo 

 sphere we first note an important omission. In dealing 

 with the lower atmosphere of the sun, and the beautiful 

 observations by which it was tirst recognised in 1870, 

 Professor Young calmly leaves out all reference to the 

 name of the eminent astronomer to whom the discovery 

 was due — Professor Young, then of Dartmouth, now of 

 Princetown, N.J. We find an account of the invention of 

 the method of observing the prominences ^nthout an eclipse, 

 in which, while due credit, to say the least, is given to 



Janssen and Lockyer for their success in observing the bright 

 lines of the prominences without an eclipse, tlie important 

 share which Dr. Huggins had in the work is not overlooked, 

 as it has been by some writers. " It seems to have been 

 reserved,' he says, "for Dr. Huggins to be the first to show 

 practically that a still simpler device would " serve to show 

 the whole contour and detail of a protuberance at once — 

 that simple device being the one actually in use, and the 

 only one which has ever been successful, the widening of 

 the slit. The account of the varf -is orders of prominences 

 is very full of interest, and, thougA . concisely written, it is 

 the best and fullest extant. 



Professor Young's discussion of the corona is, naturally, 

 full of interest to myself. When I first made his acquaint- 

 ance in America, the views which I had advocated respecting 

 the corona were as yet but half accepted. In 1869, a certain 

 degree of controversial energj' had characterised the contra- 

 diction which Mr. Lockyer advanced against the belief 

 which I then asserted to be mathematically demonstrable, 

 that — apart from any further observations — the solar corona 

 is a truly solar phenomenon, and not due to our own 

 atmosphere. But during the eclipse of 1870, photographic 

 observations showed that the theory which had lieen 

 rashly characterised as " ridiculous," is, as a matter of fact, 

 true. Even then, however, a section — a very small one 

 truly — of solar students, maintained that only the inner 

 and brighter part of the corona lielongs to the sun, the 

 outer part being a partly optical, partly atmospheric, phe- 

 nomenon. The eclipse of 1871, during which two sets of 

 six photographs, all agreeing together, were made, enforced 

 a still further concession of coronal matter to the sun. 

 For my own part, I was content to wait, the clear evidence 

 of mathematics (elementary enough, too), assuring me 

 that scarcely any appreciable portion of the light seen out- 

 side the body of the eclipsing moon could come from other 

 than solar matter — that is, matter by the sun. It did not 

 seem to me worth while to arg\ie the matter ; there had 

 been enough, and more than enough, of argument, approach- 

 ing sometimes to dispute ; and I had had time to see that 

 science can never gain by contention, though controversy 

 has not always been unfruitful. At last the eclipse of 

 1878 disposed of aU that had been in question. And 

 in Professor Young's book, we find a picture of 

 the corona of 1878, combined fi'om various draw- 

 ings, showing the real solar corona extending to a distance 

 corresponding to some three million miles from the sun. 

 Referring to these later views. Professor Young remarks 

 that " as has been pointed out by Mr. Proctor, the observer 

 at the middle of an eclipse is in the centre of an enormous 

 shadow, general!}- from fifty to a hundred miles in diar 

 meter. If we grant that the air retains some sensible 

 density and power of light reflection, e\en at an altitude 

 of a hundred miles, and assume for the shadow a radius of 

 only twenty miles, no particle of air illuiuinated by 

 sunlight could, under these circumstances, be found 

 within eleven degrees of the sun's apparent place in 

 the sky. If there were no corona truly solar in its 

 origin, there would, therefore, be around the moon a 

 circle of intense darkness, twenty-three degrees at least 

 in diameter; at the edge of this circle a faint illumi- 

 nation would begin, forming a luminous ring, something 

 like a halo, outside of which the sky would be lighted 

 by rays fi-om an only partially hidden sky." I could have 

 wished (it is not very important, but would have served to 

 show the value of a little reasoning applied to observations, 

 even to tolerably old ones,) that Professor Young had men- 

 tioned that this reasoning of mine was published in my 

 " Treatise on the Sun," and insisted upon in papers com- 

 municated to the Astronomical Society several months 



