y7tnc 6, 1872] 



NATURE 



lOI 



acids ; the passage from one class of alcohols, &.C., to 

 another; and very many other points of great scientific 

 \alije, too commonly oveilocked in the text-books, are 

 licie all carefully noted. As we siid, the book requires 

 aaentive iludv, but this it will cettamly repay. 



M.M.P.M. 



Tlurinal Paths to the' Pole. An Address delivered before 

 the St. Lodis iNIercantile Library .-Vssocia'don in January 

 1S72. By Silas Bent. 



I M this pamphlet the authDr repeats the sabstance of a 

 lecture delivered in 1S6S, the object of which was to show 

 that the continuations of the wa m Gulf Stream of the 

 Atlantic, and of the Japan currrnt in the Pacific, afford 

 the orly practicable avenues by which ships can enter an 

 assumed open sea round the North Pole ; and points out 

 hoA' the inore recent Arctic explorations have confirmed 

 the views then advanced. 



The author's opinions bhould derive weight fiom the 

 fact that he was one of the leadmg scientific observers in 

 tlie American expedition of 1852, during which the Japan 

 current was mapped out, and frjm his twenty-five years 

 of observations at sea. 



So fir as the warnr drift cont'nuing the Gulf Stream 

 ii.to the Arctic icgion between Spitzbergen and Nova 

 Z.-mha is concerned, the theory ot its intluence (which, 

 lijwever, can hardly be called "original," since it has 

 licen current among Arctic authorities for many years) 

 has indeed been remarkably confirmt d in the fast year by 

 I'ajcr and Weyprccht's voyage in open water to 79' N. la:. 

 But it remains to be shown that the summer current from 

 the Pacific through the narroiv and shallow passage of 

 B^hring Straits has any considerable influence on the 

 condition of the Arctic basin. In the circunipolar chart 

 which accompanies the pamphk-t, Behring Straits has 

 been carefully widened to admit the Kuro-Siwo in a breadth 

 quite equivalent to that of the Gult Stream drit. 



A considerable portion of the addicss is devoted to the 

 description of a method by which '■ were it not for the in- 

 hum ii.i y of exercising such a power,'' the whole of Europe 

 might be placed at the mercy of America. Europe derives 

 itj mdd climate from the Gulf Stream, and to divert this 

 stieam from its pre-entdirec'.ion would be to make ''Europe 

 a fiozen wddcrness." This grand result,the author believes, 

 c auld be accomplished " by the possession of the Isthmus 

 of Panama and the expenditure of half the coit of the 

 lecent war between France and Germany, in the excava- 

 tion of a sufficient width and depth of the rock only that 

 intervenes between the Caribbean Sea and the Pacific' 

 Ivlr. Bent has himself, however, thrown some doubt on the 

 entire practicability of his design by cjuoting, in a previous 

 laragraph, the belief expressed by Professor Maury that 

 the great mass of the Gulf Stream is formed by that part 

 of the equatorial current of the Atlantic which passes to 

 northward of the Antilles, and which " must be a hundred- 

 f Id greater than that which returns to the east from the 

 (]ulf of Mexico ;" he has also omitted to notice that the 

 lorce of the drift in the Caribbean Sea is not directed 

 in any degree against the narrower portion of the isthmus, 

 and we presume that even Mr. Bent would not attack 

 the plateaus of Guatemala or Mexico. K. J. 



LETTERS TO THE EDITOR 



[ I/ii Editor does not hold himself responsible for opinions expressed 

 by his cot respondents. No notice is taken of anonymous 

 communications. ] 



Spectroscopic Nomenclature 



Tiis lef.er of Ca;)tain Ilerschel upon "Spectroscopic No- 

 raaacUture," waicli appeared ill Nature of April 25 contains 

 many criticisus that .ire eminently just and timely, but there are 

 one or two points in respect to which I should like to express 

 uisscnt. 



Thus as regards the name D;, {to which he objects) for the 

 yellow line of the chromosphere spectrum, it is not easy to see 

 what other designation would better convey to the mind an idea 

 of its position in the spectrum and its importance, without in- 

 volving any assumption, or hypothesis even, as to the mateiial 

 causing it. 



To say nothing of the fact that the whole Greek alphabet 

 would not sutTice to name one in three of the bright lines which 

 have been observed in the chromosphere spe.trum, there is this 

 fu.ther difl"iculty, that if the letters are to be applied to lines in 

 the order of discovery, w is as likely to fall between a and /3 as 

 anywhere else, but if according to position in the spectrum, ihen 

 every discovtry of new lines involves a revision of the nomen- 

 clature. 



It seems doubtful therefore whether any better system is pos- 

 sible than to designate lines by reference to some standard map 

 of the spectrum, as stars are catalogued by their right ascension 

 and declination. 



An accurate chart of the solar spectrum on which the lines 

 should be mapped according to *' inverse wave-length," proposed 

 by Captahi Ilerschel himself I believe, as well as by Mr. .Stoney 

 and others, would sufficiently resemble the spectrum seen in a 

 spectroscope to be equally convenient in the observatory with 

 that of Kirchhoff, and would b; free from the reproach of arbi- 

 trariness and irregularity in its scale. Such a chart would be 

 mo^t gladly welcomed by all spectroscopi-its, and would immedi- 

 ately .supersede those of Kirchhoff and Angstrom. 



With reference to the green corona line, he writes " and now 

 we have ' 1474-' No one knows what the true position of thit 

 line is. The line 1474 K is an iron line, and it is to the last 

 degree improbable 1 hat the corona line is identical with it." I 

 am not quite sure what is meant by the second clause. If only, 

 that the position of this line •mz.y possibly (not by any means //v- 

 bably) be doubtful to the extent of \ of one of Kirchhoff's scale 

 divisions, that is about \ the distance between the two E lines, I 

 have nothing to object. 



But if the sentence is intended, as one would naturally sup- 

 p )Se, to convey the idea that the position of the line is not very 

 accurately determined, and may be considered uncertain to the 

 extent of several scale divisions, it is certainly wrong. I kiir,:.' 

 of what I affirm, and perhaps may be allowed to refer to an 

 ardcle in this journal for Feb. 2, 1871, in which the evidence is 

 stited as it was at that time, and it has received confirmation 

 since. 



Indeed as this bright line is almost always visible in the chro- 

 mosphere 10 an instrument of sufficient power, I think I may 

 confidently appeal to Mr. Lockyer or Dr. Huggins to bear me 

 out in the statement that the bright scarlet line of the chromo- 

 sphere appears to coincide no more perfectly with the dark C, 

 than does this green corona line with the dark line at 1474 K. 



I confess I am almost sorry that the spectrum of iron shows a 

 bright line coincident with 1474, for all things considered, I 

 cannot think that iron vapour has anything to do with this line 

 in the spectrum of the corona, and the coincidence has probably 

 only seived to mislead. 



But there are in the spectrum many cases of lines belonging to 

 the spectra of different metals coinciding, if not absolutely, yet 

 so closely that no existing spectroscope can separate them, and I 

 am disposed to believe that this close coincidence is not acci- 

 dental, but probably points lo some physical relationship, some 

 similarity of molecular constitution perhaps, between the metals 

 concerned. 



So in the case of the green coronal matter, is it not likely 

 that, th<:iugh not iron, it may turn out to bear some impor- 

 tant relation to that metal? And yet I for one should be 

 very glad if the application of higher dispersive power should 

 show the apparent coincidence to be merely a very close jux- 

 taposition. C. A. Young 



Uaraiiou'h College, U.S.A., May i5 



Historical Note on the Method of Least Squares 



Tins excellent method for the discussion of observations was 

 published and first practically applied by Gauss in his Theoria 

 Motus, iSoS. In the .-liiurican Journal of Science for June 

 1S71, Mr. Cleveland Abbe has shown that Prof. Robert Adrain, 

 of New IJrunswick, New Jersey, U.S., independently discovered 

 the same method in iSoS. I wish to call attention to what seems 

 to me a singular oversight in the history of this subject, viz., to 



