558 



NATURE 



[April 17, 1879 



to Catania, and fitted to a duplicate mounting in the 

 Bellini Observatory. But a number of self-recording 

 instruments will remain in the observatory, and thus 

 results will be registered during the winter months. 



Prof. Tacchini, to whom the whole undertaking owes 

 its existence, specially desires that it should be an Inter- 

 national Obserratory. With this object in view, the 

 large telescope will be fitted with a second tube, the 

 length and aperture of which can be altered at will, so 

 that astronomers from any part of the world can bring 

 with them their objectives and eye-pieces, and can fit 

 them to the telescope of the observatory. Special 

 arrangements will be made for photographing the sun 

 and moon, and for spectroscopic observations. 



The observatory will contain the large telescope 

 covered by the usual dome in the centre ; on each side 

 there will be rooms for the other instruments, and below, 

 sleeping quarters, a dining-room, and kitchen for the use 

 of travellers. The following plan, for which, together 

 with many of the above facts, we are indebted to Prof. 

 Tacchini, will show the general arrangement of the 

 observatory. 



In his report on the subject Prof. Tacchini commences 



by pointing out that since the year 1868 the study of the 

 physical constitution of the sun has made very rapid pro- 

 gress. In these studies the spectroscope has played a 

 very important part. But the spectroscopic observations 

 are often hindered, and their exactitude is disturbed by 

 atmospheric causes, and these disturbances are mainly 

 due to the lower layers of the atmosphere. Hence an 

 observatory at a considerable elevation would greatly 

 facilitate such observations. The isolated Mount Etna 

 affords an admirable locality for such an observatory. 

 The blueness of the sky is intense, the stars shine with an 

 extraordinary brightness, Venus casts shadows, spectro- 

 scopic lines which cannot be seen at the Palermo Obser- 

 vatory are perfectly distinct Avhen viewed from an eleva- 

 tion of 10,000 feet. "Ora il mio desiderio," says Tac- 

 chini, " sarebbe quello di andare suU' Etna per verificare 

 la tanto decantata purezza del cielo e il suo colore spe- 

 ciale, osservare 1' aureola del sole, studiarne lo spettro se 

 sark possibile e fare anche qualche tentativo di fotografia. 

 . . . ." He then mentions some of the obserrations 

 made by Young with a 9-inch refractor at an elevation of 

 2,800 metres, and describes his own observations made 

 on Etna with a DoUond refractor of 99 mm. aperture, 



P-'-Qn 



a, b, c, the three rooms of the already existing Casa Inglesi ; d, circular chamber, ^ r^ i i diameter, with a massive pillar in the centre, upon which 

 the great refractor will be placed; e, a room for guides who accompany those who ascend the mountain; ^, kitchen and offices; i, stable for 

 mules; A, staircase. On the upper fl^or, a,b,c,^i\\ be bed-rooms; e, g, i, instrument-rooms; and a?, the circular chamber for the refractor, 

 extending through both floors, and surmounted by a. movable dome of iron. 



and a spectroscope of great dispersive power constructed 

 by Tauber. " La cromosfera era magnifica e dettagliata 

 abbastanza tenendo conto della piccolezza del magnesio 

 e dello 1474, cio che non vidi a Palermo collo stesso can- 

 nocchiale." Then having made the suggestions which 

 are in part carried out, and which have entirely been 

 adopted, he concludes by a fervid peroration which we 

 heartily endorse : — " lo ritornero dunque all' Etna, lo 

 spero, e in migliore stagione, e sin d'ora mi figuro coll' 

 immaginazione, la vista della nuova specola, che mi 

 ricordera I'epoca fortunata e la circonstanza solenne, che 

 qui mi tiene ora unito a voi, e il nome del grande Bellini, 

 che prima ancora di dare alle scene il suo capo lavoro, la 

 Norma, voile in omaggio alia scienza degli astri, suonare 

 air osservatorio di Palermo la celeste melodia della 

 preghiera alia casta Diva." 



While we feel perfectly convinced that important re- 

 sults will accrue to more than one science from the estab- 

 lishment of the new observatory, we must not shut our 

 eyes to the fact that many difficulties will have to be 

 encountered. The observatory on Vesuvius stands upon 

 a projecting spur of rock, and lava-streams of any ordi- 



nary magnitude breaking out on this side of the cor 

 would divide, and leave the observatory as on a rockj 

 island. But the Etna Observatory will stand near th€ 

 upper termination of the Piano del Lago, the plain out o^ 

 which the great cone of Etna rises. A great eruptionJ 

 leading to the breaking down of the cone and flow ol 

 lava in this direction, could not fail to overwhelm th< 

 Observatory. Fortunately the lava usually finds vent b^ 

 a docca del fuoco on the sides of the mountain below the 

 great cone. The building must be of very great strength j 

 it wull be subject to violent shocks of earthquake, to fierc^ 

 storms of wind, and to the accumulation of great masses 

 of snow upon its dome and roof. Those who have read* 

 the history of the mountain know with what tremendous 

 power it scatters its terrors abroad ; how hours of loud 

 bellowings and detonations are followed by days of violent 

 earthquake, and weeks during which many square miles—j 

 of country are inundated by millions of cubic yards o^Hj 

 molten lava. That the new Observatory may flourish,™; 

 nnassailed by the fearful forces of the imprisoned Cyclops, 

 will be the wish of all our readers. 



G. F. RODWELL 



