January ♦'! 2, 1893] 



NATURE 



26 



Stars of Decreasing Temperature. 



Stage I. — Owing to the di- 

 minishing depth of the absorb- 

 ing atmosphere, the hydrogen 

 lines will, on the whole, get 

 thinner, and new lines will 

 appear. These new lines will 

 not necessarily he iiientical 

 with those observed in the 

 spectra of stars of increasing 

 temoeraiure. In the latter 

 there will be the perpetual 

 explosions of the meteorites 

 affecting the atmospheres, 

 whereas in a cooling mass 

 of vapour we get the absorp- 

 tion of the highest layers of 

 vapours. The first lines to 

 appear, however, will be the 

 longest low-temperature lines 

 of the various chemical ele- 

 ments. 



Stage 2. — The hydrogen 

 lines will continue to thin 

 out, and the spectra will 

 show many more of the high- 

 temperature lines of differ'-nt 

 elements. These will differ 

 from the lines seen in stars 

 of increasing temperature 

 owing to the different per- 

 centage composition of the 

 absorbing layers, so far as 

 the known lines are con- 

 cerned. 



Sta;e 3.— With the further 

 thinning out of the hydrogen 

 lines and reduction of tem- 

 perature of the a'mo-phere, 

 the absorptiiin flutings of the 

 compounds of carbon should 

 come in. 



Taking Sirius as a type of 

 stars in the first sta^e of de- 

 creasing temperature, it is 

 found that its spectrum shows 

 many of the longest lines of 

 iron. 



The conditions at this stage 

 of cooling are satisfied by such 

 stars as /3 Arietis and a Persei. 

 In the spectrum of these stars 

 nearly all the solar lines are 

 found, in addition to fairly 

 broad lines of hydrogen. 



There is undoubted evi- 

 dence of the presence of 

 carbon absorption in the 

 solar spectrum and the S|iec- 

 trum of Arcturus, the only 

 star which has yet been in- 

 vestigated with special refer- 

 ence to this point. 



The photographs, then, give us the same results as the one 

 formerly obtained fro ■> the eye observations. 



Comparison is ih'-ii made between the groups in the classifi- 

 cation first sugjjested by the eye observations, and the various 

 sub-ilivi>ion- in which the photographs have been arranged. 



Geological Society, December 7. — W. H. Hudleston, 

 F. R. S., President, in the chair. — The following communica- 

 tions were read : — Note on the Nufenen-stock (Lepontine Alps), 

 by Prof. T. G. Honney, F.R. S. In 1889 the author was { 

 obliged to leave some work incomplete in this rather out-of-the- 1 

 way portion of the Lepontine Alps. In ihe sum iier of 1891 he j 

 returned ttiither in company with Mr. J Eccles, F.G.S., and , 

 the present note is supplementary to the former paper. The 

 Nufenen-stock « as traversed from north to south, and a return 

 section made roughly along the eastern bank of the Gries 

 Glacier, (jneiss al)ounds on the north side of the Nufenen 

 Pass, followed by rauchwacke and some Jurassic roci- . On the 

 flank of the mouniain are small outcrops of rauchwacke and of 

 the so-called " Uisiheneschists" (boih badly exposed), followed 

 by much Dark-mica schist, often conlaiuir.g black garnets. 

 Higher up is a considerable mass of Jurassic rock with the 

 "knots" and " i.risms" which have been mistaken for garnets 

 and siauroliies, but Dark-mica schists set in again before the 

 summit is reached. Ihey cominue d.»wn ihe southern flank of 

 the peak : but rather north of the lowest part of the water shed, 

 between Switzerland and Italy, the " Disthene schist " is again 

 found, followed by a fair-sized mass of rauchwacke. The re 

 turn sec ion gave a similar as-ociation in reverse order; and 

 both confirmed the conclusions expressed by theauth -r in 1890 

 as to the ai)sence of garnets and stauroliies from Jurassic rocks 

 (with belemnit s, &c.). and the great break between these or 

 the underlying rauchwacke (where it occurs) and the crysiallme 

 schists, ill which garnets often a >ound, of the Lepontine Alps 

 The crystalline schi^ts and the Mesozoic rocks are thrown into 

 a Strict of very sharp folds, which, locally, presents at first 

 sight the appearance of interstratification. — On some schistose 



NO. 12 1 1, VOL. 47] 



"greenstones" and allied hornblendic schists from the Pen- 

 nine Alps, as illustrative of the effects of pressure-metamor- 

 phism, by Prof. T. G. Bonney. The author describes the results 

 of study in the field, and with the microscope, of (a) some thin 

 dykes in the calc-schist group, much modified by pressure ; 

 [b) some larger masses of green schist which appear to be closely 

 associated with the dykes ; (<:) some other pressure-modified 

 greenstone dykes of greater thickness than the first. The speci- 

 mens were obtained, for the most part, either near Saas Fee or 

 in the Binnenthal. These results, in his opinion, justified the 

 following conclusions : — (l) That basic intrusive rocks, pre- 

 sumably oncedoleritesor basalts, can be converted into foliated, 

 possibly even slightly banded, schists, in which no recognizable 

 trace of the original structure remains. (2) That in an early 

 (possibly the first) stage of the process, the primary constituents 

 of the rock-mass are crushed or sheared, and thus their frag- 

 ments frequently assume a somewhat "streaky " order ; that is 

 to say, the rock passes more or less into the "mylonitic" con- 

 dition. (3) That next (probably owing to the action of water 

 under great pressure) certain of the constituents are decomposed 

 or dissolved. (4) That, in consequence of this, when the 

 pressure is sufficiently diminished, a new group of minerals is 

 formed (though in some cases original fragments may serve as 

 nuclei) (5) That of the more important constituents hornblende 

 is the first to form, closely followed, if not accompanied, by 

 epidote ; next comes biotite (the growth of which often suggests 

 that by this time the pressure is ceasing to be definite in direc- 

 tion) ; and, lastly, a water-clear mineral, probably a felspar, 

 perhaps sometiuaes quartz. (6) That in all these cases the 

 hornblende occurs either in very elongated prisms or in actual 

 needles. The author brings forward a number of other instances 

 to show that this firm of hornblende may be regarded as 

 indicative of dynamometamorphism ; so that rocks where that 

 mineral is more granular in shape (cases where actinolite or 

 tremoliie appears as a mere fringe being excepted) have not been 

 sutijected to this process. — On a secondary development of bio- 

 tite and of hornblende in crystalline schists from the Binnenthal, 

 by Prof. T. G. Bonney. Both the rocks described in this com- 

 munication come from the Binnenthal, and were obtained by 

 Mr. J. Eccles, F.G.S., in the summer of 1891. They belong 

 to the Dark-mica schists described by the author in former 

 papers, and have been greatly affected by pressure. In each a 

 mineral above the usual size has been subsequently developed. 

 In the rock from near Binn this mineral is a biotite : the dimen- 

 sions of one crystal, irregular in outline, and having its basal 

 cleavige roughly perpendicular to the lines indicative of pres- 

 sure, are about •I75"X03". The other mineral, from the peak 

 of the Hohsandhorn, is a rather irregularly- formed hornblende, 

 the crystals (which lie in various directions) being souietimes 

 more than half an inch long. The exterior often is closely asso- 

 ciated with little flakes of biotite. The author discusses the 

 bearing of this fact, and the circumstances which may have 

 favoured the formation of minerals, so far as his experience 

 g les, of an exceptional size. Some remarks also are made on 

 relation of these structures developed in the Alpine schists to 

 the various movements by which those rocks have been affected, 

 and on the general question of pressure as an agent of metamor- 

 phism. The reading of the^e papers was followed by a discus- 

 sion, in which the President, Mr. Eccles, the Rev. E. Hill, Mr. 

 Rutley, Mr. Teall, and the author, took part. —Geological notes 

 on the Bridgewater District in Eastern Ontario, by J. H. 

 Collins. 



Paris. 



Academy of Sciences, January 2.— M. d'Abbadie in the 

 chair. — M. Loewy was elected Vice-President for 1893. MM. 

 Fizeau and Fremy were elected into the central committee of 

 administration. The President gave a list of the members, 

 associates, and correspondents deceased and elected during 1892. 

 The new members were MM. Appell, Perrier, Guyon, and 

 Brouardel. Foreign associates, MM. von Helmholtz, and van 

 Bi-neden. Correspondents, MM. Sophus Lie, Considere, 

 Amsler, Auwers, Rayet, Perrotin, de Tillo, and Manen.— 

 Observations of Brooks's couiet (November 19, 1892) made with 

 the equatorial coudi of the Lyon Observatory, by M. G. Le 

 Cadet. — On a new method of approximation, by \^. E. Jablon^ki. 

 — On the movements of systems whose trajectories admit of an 

 infinitesimal translormalion, by M. Paul I'ainleve. — On the 

 general form of vibratory motion in an isotropic medium, by 

 M. E. Mercadier. — On thermo-electric phenomena between two 



