Sept. 29, 1S81] 



NATURE 



507 



but we are rather sorry to find the authoress enthusiastic 

 at the passing of the " Injurious Insects" Act of Parlia- 

 ment, which we prefer to consider the outcome of a scare 

 furthered by speculators. All we can say for the " Intro- 

 duction to Entomology " is that it will possibly serve to 

 give the class for whom it is intended sounder ideas on the 

 subject than generally prevail with them ; the Glossary at 

 the end is too short to be of much service. 



Ziii7i : eine geologiscli-7iiontanistisch-hist07'ische Mono- 

 graphic. Von E. Reyer. 8vo. (Berlin: Reimer, 1881.) 

 In this monograph, as is indicated by the agglutinative 

 adjective on the title-page, the author has collected the 

 results of his studies on the technological history of the 

 metal tin under the threefold head of geology, mining, 

 and history; or rather the reader may do so for himself 

 from the material which is presented in an abrupt fashion 

 without either preface or index. The first part of the 

 volume is devoted to descriptions of the tin-producing 

 districts of Sa.xony and Bohemia, the geological features 

 of each district being fiist considered, then its history as 

 derived from the local archives and notices in published 

 chronicles, the whole of the facts concerning production 

 being summed up in a chronicle of tin mining in Bohemia 

 and Saxony, with tabular statements and diagrams of the 

 production from the earliest period for which records are 

 obtainable, about the year 1400, down to the present time. 

 From these we gather that the total production of both 

 countries, which was about 100 tons in the year 1400, 

 reached in 1500 a maximum of about 1000 tons, since 

 which time it has steadily declined, the produce at in- 

 tervals of fifty years varying from 75 to 125 tons annually. 

 At the present time the production is practically confined 

 to Altenberg in Saxony, where about 50 tons are obtained 

 from the treatment of a staminiferous granite containing 

 about 8 lbs. of tin ore per ton. In subsequent sections of 

 the volume the productions of Cornwall, Banca, and 

 Australia are treated in a similar manner ; a descriptive 

 sketch of the geology of each locality being given in each 

 case, followed by a chronicle of events and prices. These 

 being mainly compiled from well-known sources, such as 

 De la Beche's " Cornwall and Devon," Von Diest's 

 "Banca," the reports issued by the -Australian and Tas- 

 manian Colonial Governments, &c., present less of novelty 

 than the first part, which contains much original matter 

 derived from the author's own investigations ; but the 

 skilful manner in which the information is presented is 

 likely to render the volume very useful to those interested 

 in the subject. An unnecessary difficulty has been intro- 

 duced by the adoption of the new-fashioned phonetic 

 system of spelling which has latterly become prevalent in 

 Berlin, and will doubtless prove a puzzle to many readers. 



H. B. 



LETTERS TO THE EDITOR 

 [ The Editor docs not hold himself responsible for opinions expressed 

 by his correspondents. A'either can he undertake to return, 

 or to correspond with the writers of, rejected manuscripts. 

 No notice is taken of anonymous communications. 

 [ The Editor urgaitly requests correspondents to keep their letters 

 as short as possible. The pressure on his space is so great 

 that it is impossible othenvise to ensure the appearance even 

 of communicaticns containing interesting and novel facts,'\ 



The Progress of Meteor-spectroscopy 

 In the profound and eloquent review of the progress of British 

 and other discoveries in science during the last half century given 

 in the Opening Address to the Uritish Association at its recent 

 Jubilee Meeting in York by its President, Sir John Lubbock, 

 I am credited (Nature, vol. x.xiv. p. 409) with some meteor- 

 spectrum observations which, while they certainly unfold >onie 

 of the most important results arrived at in meteor-spectroscopy 

 since its commencement in the year lS66, yet owe their recogni- 

 tion a-s scientific discoveries of some material weight and real 

 consequence, to quite a different author. 



Although with the first useof a meteor-spectroscope I recognised 

 in the persistent streaks of the August Perseids of that year 

 numerous examples of the yellow-sodium line, yet no proof was 

 furnished by the slender spectroscopic power employed, of the 

 existence in the meteor-streaks of any other substance. It was 

 by a Hungarian astronomer, von Konkoly, that the presence 

 of " lithium, potassium, rnd other substances " in the streaks of 

 shooting-stars w as afterwards discovered ; and of seme of these 

 .'Ubstances Herr von Konkoly obtained .nich repeated and well- 

 verified observations, that the identification of their spectro- 

 scopic presence in certain meteor-streaks may be regarded as 

 satisfactorily established. 



The instruments made by Mr. Browning for the British 

 Association Meteor-Committee in the year just mentioned were 

 intended to be used in studying the spectra of the November 

 Leonids, whose magnificent display took place as expected, but 

 was of such short duration that nothing of great importance 

 was, unfortunately, elicited as regards their specra. A more 

 successful trill of the instruments had however been made 

 previously on the gth-iiih of August of the same year,' and 

 abundant evidence was then obtained of the existence of two 

 classes of meteor-streaks, both equally persistent, one of them 

 affording a continuous spectrum only, like what hot sparks or 

 train-matter would produce ; the other more or less charged with, 

 and sometimes consisting entirely of the yellow sodium-line. 



No distinct evidence was obtained, however, in that first 

 year's experimental trials of the occurrence in meteor-streaks 

 of any other elementary spectrum-lines lesides the solitary 

 sodium one. The spectra of the nuclei were continuous, the 

 brightest ones showing all the prismatic colours in perfection ; 

 and only one or two at the same time allowed some traceable 

 evidence of sodium to be detected in their light. But a few 

 of the green "Leonid" streaks were noticed in November to 

 be, to all appearance, monochromatic, or quite undispersed by 

 vision throuj;h the refracting prisms ; from which we may 

 at least very probably infer (by la.er discoveries with the meteor- 

 spectroscope) that the prominent green line of magnesium forms 

 the prii cipal constituent element of their gi-eenish light. 



Meteor-spectroscopes of a more efficient kind were afterwards 

 devised and produced by Mr. Browning. But they remained, 

 as far as I am aware, without any successful application until 

 the nights of July 25th and 26, 1873, "hen the spectra of three 

 streak-leaving shooting-stars were observed through one of them 

 by the enthusiastic astronomer of O'Gyalla, near Komorn in 

 Hungary, Herr von Konkoly.- The streaks of tlie first two 

 meteors seen showed only the sodium-line ; lut in that of the 

 third, which was an emerald-green meteor, the green spectral 

 line of magnesium (Fraunhofer's solar line b) was plainly 

 visible in addition to the yellow sodium-line. The spectra 

 of the nuclei were continuous, only the green region of the 

 spectrum in that of the last meteor being of unuual brightne=s. 



On the morning of the 13th of October in the same year 

 Herr von Konkoly again observed with Browning's meteor- 

 spectroscope the long-enduring streak of a large fireball, which was 

 visible in the north-east at O'Gyalla. It exhibited the yellow 

 sodium-line and the green line of magnesium very finely, besides 

 other spectral lines in the red and green. Examining these 

 latter lines closely with a star-spectroscope attached to an 

 equatorial telescope, Herr von Konkoly succeeded in identi- 

 fying them by direct comparison with the lines in an electric 

 Geissler tube of marsh-gas.' They were visible in the star- 

 spectroscope for eleven minutes ; after which the sodium and 

 magnesium lines still continued to be very brightly observable 

 through the meteor-spectroscope ; and the streak faded out of 

 sight m a comet-seeker, at last, twenty-five minutes after it wa'^ 

 first observed. 



In July and August, 1879,'' and in August, 1880,° Herr von 

 Konkoly observed spectra of the nuclei and streaks of many 

 Perseids and other meteors with the Browning's meteor-spectro- 

 scope. The yelLiw sodium-line was conspicuous in most of the 

 streak-spectra, and adjoining it there were seen in many cases 

 the red line of lithium and another more distant red line sup- 

 posed to be that of potassium ; but the violet line of potassium, 



» The Intellectual Ohsemer, vol. x. pp. 38 and (with a coloured plate) 

 61 ; August and October, 1866. 



a Monthly Notices of the Royal Astronomical Society^ vol. xx.xiii- 

 (1872-73), p. 575. 



3 Monthly Notices 0/ the Royal Astronomical Society, vol xxxiv. (1873-74), 

 p. 82. Ttie description " lightning-gas " there given of the tube is, as Her- 

 von Konkoly afterwards informed me, a misprint for "lighting." oi 

 "coal-gas," "mit welchem die Strassen beleuchtet sind." 



4 The Observatory, vol. iii. p. 157. ' Ibid., p. 577. 



