526 



NATURE 



{April i, 1880 



appeared in this column last week, gives the right ascension 

 greater by 1" 29' and the declination further south by 21' ; though 

 the Cordoba observation is called a rough one, under the circum- 

 stances it will hardly be liable to such errors, and may be at least 

 comparable in accuracy with the approximate positions received 

 from the Royal Observatory at the Cape. If we combine it with 

 the Cape places on February 10 and 15 for the determination of 

 the orbit, the following remarkable elements result — we say 

 remarkable from their being almost identical with the elements 

 of the grand comet of 1843, as will be seen from the orbit 

 annexed : — 



c ., -c 00 Great comet of i S41 



Comet of 1880. (Hubbard . s parab \ly 



Ferihelion passage Jan. 27 - 6o27 



Longitude of perihelion 279 6"8 ... 27S 35*1 



,, ascending node ... 4 I '9 ... 1 2o - 6 



Inclination 35 398 ... 35 38'2 



Log. perihelion distance 777371 ••• 7'74'23 



Motion ... Retrograde ... Retrograde 



If this close resemblance is the result of accident, and the true 

 orbit of the comet more like that published last week, the coin- 

 cidence is a very unusual one in such computations, and in fact 

 not far from an unique case. 



Prof. Hubbard, from his rigorous investigation of the orbit of 

 the great comet of 1S43, concluded that the period extended to 

 several centuries, though before the comet was beyond reach of 

 the telesope it was conjectured that the revolution might be 

 comparatively short, and from a similarity in the appearance of 

 the comets of 1668, 1702, and 1843, a period of about thirty-five 

 years was considered probable by many astronomers. Pending 

 the arrival of accurate observations from the southern hemi- 

 sphere, which may decide the true form of orbit, it may be 

 worth while to examine with large telescopes the vicinity of 

 positions calculated from the orbit which so closely resembles 

 that of the comet of 1843, as, in the event of identity, observa- 

 tions of position made now would have great value. For 8h. 

 Greenwich mean time the above orbit gives the following 

 places : — 



c a N P T) Lo S- distance 



K.A. N.r.U. from Earth. 



PHYSICAL NOTES 



M. Ducretet has made the important observation that 

 "toughened" glass is less easily penetrated by the electric 

 spark than ordinary glass. He proposes to apply this dis- 

 covery in the manufacture of superior Leyden jars. It is almost 

 needless to point out that a means of making powerful condense s 

 of more conpnct form is afforded by the employment of the 

 toughened article. The very important bearing of the matter 

 upon the whole question of dielectric strain and the elastic 

 recovery of bodies is a point which will probably receive due 

 attention at the hands of physicists. 



The residual charge of the Leyden jar has been recently 

 investigated afresh by Herr Giese (IVieJ. Ann., No. 2). It 

 seemed desirable to follow the course of formation of this charge 

 Under conditions more amenable to analytical treatment than has 

 hitherto been the case, and to make the phenomenon independent 

 of external influences. This he sought to attain by determining 

 the quantity of electricity which flowed to the coatings when the 

 difference of potential was keot constant. His method is fully 

 detailed in the paper referred to, and the re.-ult he is led to is 

 that the formulae of Rieuiann (who offered the hypothesis of an 

 antelectric state of matter, at a meeting of scientists in Gottingen 

 in 1854) are not in harmony with experiment. 



A paper by Prof. Rammelsberg, "On the chemical mono- 

 graphy of the mica group," has lately appeared in Wiedemann's 

 Annaloi (Nos. 1 and 2). As to the kind of relations that exist 

 between the chemical nature of micas and their other properties, 

 he remarks that there are differences in corresponding angles, 

 though the amount can be ascertained only in few cases. 

 Optical differences can be determined with more certainty ; in 

 this respect all alkali-micas, whether containing sodium, 

 potassium, or potassium and lithium, are alike. The plane of 

 the optic axes is at right angles to the plane of symmetry. 



Pure magnesia-micas are the opposite in this respect. Among 

 the iron-magnesia-micas there are some which are optically 

 like the alkali micas, but more which are like the pure 

 magnesia-micas. In the lithium-iron micas of Zinnwald the 

 axes are as in the last-mentioned micas. The baryta-mica of 

 Sterzing is optically like the alkali-micas. From all this it 

 results that any classification of micas can only be a chemical 

 one. But so long as we do not know whether the (qualitative) 

 chemical nature coincides with the subdivision hitherto adopted 

 (muscovite, phlogopite, biotite, &c. ), which however rests only 

 on physical differences, we cannot exchange the certain chemical 

 names with those which are derived from some special physical 

 character, e.g. , the position of the plane of the optic axes. 



To the scientific applications of centrifugal force which have 

 been made since the time of Musschenbrcek, who, in his treatise 

 on Physics, calls attention to the utility of it, Prof. Thury of 

 Geneva (Arch, de Sci„ January) thinks the following might be 

 added : —Measurement of the adhesion of liquids and solids ; 

 separation, total or partial, of a dissolved body from its solvent ; 

 separation of the constituents of alloys (kept in fusion by means 

 of Bunsen burners) ; separation of liquids of different densities ; 

 production of high vacua ; modification of crystalline forms 

 (possibly); depolarisation of electrodes in some circumstances of 

 electrolysis ; modification of the organisation of embryos in the 

 egg ; observation of a body in very rapid circular motion, as if 

 it were motionless. 



Signor Acostini finds [A T a/wa, 3) that if through a drop of 

 mercury, lying on a surface not wet by it, a current be sent in 

 vertical direction, it rotates under the influence of the earth's 

 magnetism, as may be seen if a few particles of lycopodium 

 powder be strewn on it. Similarly a mercury drop rotates when 

 placed on the surface of a steel magnet, and e.g. the magnet 

 connected with the positive pole of a very weak element, while 

 an electrode penetrating the drop from above is connected with 

 the negative. From the strength and direction of rotation ot a 

 number of such drops one may in general make visible the dis- 

 tribution of the magnetism, the neutral points, &c, both in the 

 magnetic bars themselves, as when an iron bar is brought co- 

 axially near to one end, or into contact ; also in the latter. The 

 results of previous experimental measurements are thus confirmed. 



GEOGRAPHICAL NOTES 



Prof. Nordeuskjold reached London on Friday last, several 

 days after he was expected, thus upsetting all the arrangements 

 which were made for his reception. He is, we understand, to 

 leave for Paris to-day to receive the'GreatGold Medal of the Geo- 

 graphical Society and the distinction of Commander of the 

 Legion of Honour. While here he has been entertained in a 

 quiet way by various distinguished people ; among others by the 

 Swedish Minister, the Earl of Northbrook as president of the 

 Geographical Society, Mr. Spottiswoode, president of the Royal 

 Society, Sir Allen Young, an 1 others. Doubtless he will return 

 to London at a time more convenient to give him the public 

 reception which he merits. 



It is stated that Lieut. Bove, who accompanied Nordeuskjold 

 in the Vega, has gone to Rome to submit to the King of Italy 

 and the cabinet a plan for an Italian expedition to the South 

 Pole. 



A letter recently received from Capt. Howgate mentions 

 that, whether aided or not by the (U. S.) Government, he is 

 determined to start an expedition to the Arctic regions this year. 

 The s.s. Gulnari is now on the "ways," being fitted up for 

 ice navigation under the superintendence of Capt. Chester, who 

 was witli Hall in the Polaris. A house of wood — double boarded 

 — 21 x 6S feet, modelled after tho-e used by the Hudson's Bay 

 Company, is being constructed for the men to winter in on the 

 shores of Discovery Harbour, and will be ready by April I. 

 A steam launch will probably form part of the expedition. 



The Japan papers state that the Russian Government have 

 deter inined to despatch a man-of-war to make a hydrographical 

 survey of the Japanese seas and the Sea of Okhotsk. The 

 Geigraphical Society of St. Petersburg have been invited to 

 send a representative with the expedition, and it is believed that 

 Prof. Amantevitch will be selected on account of his knowledge 

 of the Japanese language and the dialects spoken on the east 

 coast of Siberia. 



Mr. G. F. Easton, the agent of the China Inland Mission at 

 Tsin-chow in the Kansu province, has sent home an account of 



