262 



NATURE 



[Jan. 18, 



1877 



vigilant outlook for what may be called the grosser 

 changes of atmospheric pressure and of the wind, and a 

 very moderate knowledge of meteorology for their in- 

 terpretation. So clearly is this the case that notwith- 

 standing the great advances made by nieteorology in 

 recent years no progress has been made in this country in 

 issuing warnings of the approach of storms, since the 

 number of fresh gales (8 of Beaufort-scale) of which 

 warnings have been sent are still somewhat under the 

 percentage of success attained by Fitzroy in 1864. 



But in India it is different. Any system of storm- 

 warnings there, to be successful, must be based on a 

 refined system of observation carried on at a considerable 

 number of stations in such positions as we have pointed 

 out — those positions being selected with special reference 

 to this inquiry. 



OUR ASTRONOMICAL COLUMN 



An Observatory on Etna. — Prof. Tacchini sends us a 

 note read before the Accademia Gioenia on September 22, 

 1876, entitled, *' Delia convenienza ed utilita di erigere suU' Etna 

 una Stazione Astronomico-Meteorologica," in which after describ- 

 ing his experiences during a brief ascent on September 15-16, 

 he expresses his views with regard to the establishment and most 

 desirable fitting of an observatory on the mountain to be mainly 

 devoted to spectroscopic and meteorological observations. 



Prof. Tacchini ascended on the morning of September 15 

 from Catania to the station occupied by a party of the 

 English and American expeditions on the occasion of the 

 total solar eclipse of December, 1870, and found there a 

 diminution of temperature of 33° Centigrade. He had taken 

 with him a Dollond-telescope of 3|- inches aperture, a spec- 

 troscope of strong dispersion by Tauber, a small spectroscope 

 of Jannsen, an aneroid barometer, thermometers, and a pola- 

 riscope. At loh. 30m. A.M., on the i6th, a few detached clouds 

 only being present, he remarked that the blue of the sky was 

 much deeper than at Palermo or Catania. The solar light 

 had a special character, it seemed whiter and more tranquil, as 

 though due to artificial illumination by magnesium. Viewing the 

 sun rapidly with the naked eye, it was seen as a black disc sur- 

 rounded by an aureola of limited extent, projected on the blue 

 ground of the sky. On interposing an opaque body before the 

 disc the aureola was seen better but always limited, and the pure 

 blue sky terminated the same, which extended to rather more than 

 half the solar radius ; with the naked eye it was difficult to judge 

 if the aureola was of equal breadth all round the disc, and the 

 only thing well marked was the difference from the view obtained 

 at the level of the sea ; while the sky is ordinarily whitish about 

 the sun, on Etna it remained blue, and the aureola acquired a 

 better-defined contour. With a helioscope the aureola was much 

 better seen, and its border appeared irregular, and as though 

 it were rather more extended at four points, which, at noon, cor- 

 responded to the extremities of the vertical and horizontal diame. 

 ters of the disc. At 3 P.M., after interruption from clouds which 

 in passing rapidly at short intervals produced a striking effect by 

 the formation of a stupendous series of coloured rings round the 

 sun containing all the gradations of colour in the spectrum, a 

 phenomenon new to Prof. Tacchini, the Tauber-spectroscope 

 was applied to the telescope for examination of the solar 

 spectrum, and the observer expresses his surprise at the fine 

 definition of the lines and the extraordinary distinctness of the 

 whole ; the chromosphere was bright. 



In the evening at loh., the spectacle of the starlit sky was 

 novel and enchanting. Sirius appeared to rival Venus, the finer 

 constellations acquired an altogether special aspect, and the ap- 

 pearance of the Via Lactea was astounding. The image of the 

 planet Saturn was admirable, and the peculiarities of the ring 



and belts were seen to much greater advantage than at Palermo, 

 shortly before leaving. Venus afforded remarkable proof of the 

 rare quality of the sky of Etna. The planet shone with a power- 

 ful light, which cast shadows during the ascent of the mountain ; 

 it scintillated frequently like a star. The telescope showed, on 

 the northern part of the phase, an oblong space, less illuminated 

 than the rest of the disc, which Prof. Tacchini says was " sicura- 

 mente una macchia del pianeta." 



Spectroscopic observations were renewed on the following 

 morning, when the sun had attained an altitude of 10°. The 

 chromosphere was "magnificent ;" the inversion of the magne- 

 sium and of 1474 was immediately evident, which was not seen 

 at Palermo with the same telescope. 



"With regard to the proposed observatory which Prof. Tacchini 

 is desirous should be an accomplished fact before the meeting of 

 the scientific bodies at Rome, in September next, he proposes 

 that it should be erected at the Casina degl ' Inglesi, and should 

 be named after Bellini, and that it should belong to the Univer- 

 sity of Catania. He suggests that it ought to be provided with 

 a refractor of first-rate quality and of at least 16 centim. (about 

 6 '3 inches) aperture, and he advises that while the meteorologi- 

 cal instruments, which should be adapted to the requirements of 

 the day, as indicated by the London Congress, would remain 

 constantly at the Bellini Observatory, a duplicate mounting 

 might be provided for the refractor at some spot within the Uni- 

 versity of Catania, with its proper dome, the other being fixed 

 on Etna, so that while from June to the end of September astro- 

 nomical observations could be carried on upon the mountain, 

 during the winter they might be made at Catania, where the sky 

 is a very good one ; the astronomer would thus have only the 

 object-glass with its tube to transport to and fro. Prof. Tacchini 

 further suggests that accommodation for visitors should be pro- 

 vided, with the view to increasing their numbers, and that a 

 certain payment should be made by them, to go towards the 

 maintenance of the Observatory and its custodian. 



We wish every success to the scheme thus energetically 

 brought before the Italian authorities by Prof. Tacchini, and 

 have no hesitation in predicting important gains to science from 

 its adoption. 



The New Star of 1604. — The vicinity of this star's place 

 deserves to be closely watched, as it appears by no means im- 

 probable that the object may be identified amongst the telescopic 

 stars actually visible, by small fluctuations of brightness, which 

 there are grounds for supposing to have been the case with the 

 so-called new stars of Tycho Brahe and Anthelm. 



The best position of Nova 1604, is no doubt that deduced by 

 Prof. Schonfeld from the observations of David Fabricius, found 

 in the liiera mutua: in Fritsch's edition of Kepler's works. 

 Fabricius measured the distance of the new star from C, i\, a 

 Ophiuchi, a Aquilse, and a Scorpii, and the discussion of these 

 measures leads to the following place for 1 605*0, R.A. 256" 45' 43" 

 or I7h. ym. 2'9S., N.P.D. 111° 4' 42", with probable errors of 

 ± 2"os. and ±0"65' ; this position brought up to 18770 is R.A. 

 I7h. 23m. i6s., N.P.D. 111° 22*4'. The nearest catalogued star 

 is one of 8*9 mag. observed in Argelander's Southern Zones, ^ 

 No. 16872 of Oeltzen's reductions. Kepler's star precedes, ac- 

 cording to Schonfeld's calculsition, 25 •3s., ani is N. about 0'8'. 

 There is a star I2'i3 mag. preceding Argelander's star i8"8s. and 

 I ■& to the south, suspiciously close to the recorded place, since 

 the probable errors are no safe guide in such a case as this. 

 Chacornac on Chart No. 52, las a tenth magnitude in about 

 R.A. I7h. 2im. 50S., N.P.D. 111° 22' for 1855, which is not 

 r. ow visible or was not last summer. But the locality requires a 

 stricter and more systematic examination, which may be sug- 

 gested to some one of our astronomical readers, who possesses 

 adequate optical power, when this region of the sky is favourably 

 situated for oliservation. 



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