144 



NATURE 



[February 8, 1894 



After the restoration of the Society, however, the Jesuits 

 gained possession of this observatory in 1824, and 

 placed it under the direction of Dumouchel. De Vico, 

 whose cometary discoveries and observations of Venus 

 are so well known, was the next director, but with the 

 troubles of 1848 came the expulsion of the Society of 

 Jesus from Rome. De Vico died in London. In 1849, how- 

 ever, Secchi, who made his first observation when an exile 

 ai Stonyhurst, commenced to carry out the learned Bosco- 

 vich's plans. The observatory was rebuilt, endowed, and 

 instruments furnished at the expense of the Society of 

 Jesus, and with the generous aid of Pope Piux IX. At 

 the next expulsion of the Society, in 1870, Secchi re- 

 mained at the observatory at the express wish of the 

 Italian Government. At his death he bequeathed the 

 property of the Society to Father Ferrari, but the 

 Government appropriated the observatory and every- 

 thing connected with it. Fortunately for astronomy, how- 

 ever, Signor Tacchini was appointed to the directorship 

 of the observatory, and has well sustained its reputation. 

 It may be added that the Observatory of the Capitol, in 

 which Respighi did such good work, was founded by 

 Leo XII., and attached to the University of Rome. 



After the Vatican Exposition in 1888, in commemora- 

 tion of the fiftieth anniversary of the priesthood 

 of Pope Leo XIII., all the instruments and apparatus 

 given by members of the Roman Catholic Church inter- 

 ested in celestial and terrestrial physics were brought 

 together, and it occurred to the managers of the science 

 sections of the Exposition that they would find a suitable 

 home in the old Gregorian tower. The suggestion was 

 warmly approved and carried into effect. Father Denza, 

 a great friend of Secchi's, was appointed the director of 

 the revived observatory, and he began his work in 1889 

 with a comprehensive programme, which he and his 

 assistants Lais, Andreis, and Mannucci have well carried 

 out. The investigations instituted relate to meteorology, 

 terrestrial magnetism, geodynamics, and astronomy. 

 The building is well situated for meteorological observa- 

 tions ; it is equipped with instruments for the continuous 

 record, as well as personal observation, of meteorological 

 data. In terrestrial magnetism, also, instruments are pro- 

 vided for the determination of absolute values and the 

 registration of variations of the usual elements. The 

 chief astronomical engine of research included in the 

 observatory's outfit is a photographic equatorial of the 

 Henry pattern and mounting, for use in connection with 

 the construction of the photographic star-chart which the 

 Vatican Observatory is helping to bring to a successful 

 termination. 



Having now described the constitution of the observa- 

 tory, it remains for us to state the nature of the work 

 done, as evidenced by the reports. The first report 

 contains a long article on the prmciples and progress of 

 celestial photography, by Father Denza. Father Lais 

 reports the details of stellar photography in connection 

 with the chart, and the methods of obtaining photo- 

 graphic stellar spectra and solar pictures. He also 

 summarises the observations made in Italy during the 

 Perseid shower of August 1890, and during the Leonid 

 shower of the same year. 



Sig. Andreis describes the points to be investigated in 

 the geodynamical work of the observatory, and there is 

 a full account of the meteorological instruments and the 

 observations made with them. 



When the second report of the observatory was issued, 

 it was seen that Father Denza and his assistants had 

 carried on some useful observations during 1891. The 

 geographical position of the observatory, eclipses of the 

 sun and meon, the Perseid and Leonid meteor showers 

 of the year, formed the subjects of important articles by 

 the Director, while Father Lais and Sig. Mannucci 

 described the work that had been done in celestial 

 photography. Marvellous results were obtained with 



NO. 1267, VOL. 49] 



the Henry equatorial from the very beginning, and 

 no stronger witness of this is necessary than that 

 afforded by the beautiful plates which embellish the 

 second report. The picture of the Ring Nebula in Lyra 

 is certainly one of the best yet obtained, and that of the 

 star-cluster M 15 is equally good. Other bits of celestial 

 scenery included in the same volume are the Pleiades 

 and neighbourhood, and a cluster in Sagittarius, while 

 individual occupants of the heavens are represented 

 by three portraits of Jupiter and two views of the lunar 

 surface. 



We pass now to the report issued in the latter half of 

 last year, and which in point of excellence and abund- 

 ance of matter even surpasses the one before it. Two 

 remarkably fine portraits are given in this volume, one 

 of Pope Leo XIII., the other of the late Admiral 

 Mouchez ; and the astronomical views include the region 

 of Nova Aurigje, that of the Praesepe cluster, the Orion 

 nebula, and four sun-pictures. But none of these photo- 

 graphs are so striking as the fourteen reproductions of 

 cloud photographs obtained by Sig. Mannucci, and of 

 which we are able to give four specimens. Meteorolo- 

 gists will remember that a set of eighty cloud photo- 

 graphs taken at the Vatican Observatory were shown at 

 the Royal Meteorological Society's Exhibition in 1890. 

 Sig. Mannucci's experience indicates that in cloud 

 photography very short exposures do not give the best 

 results. Plates of medium rapidity, having a thin film, 

 seem to give the boldest contrast between the blue of the 

 sky and the masses of diaphanous haze that are some- 

 times projected upon it. Such plates also show the 

 greatest amount of detail in large masses of cloud. 



Sig. Mannucci gives a brief account of systems of cloud 

 classification in the volume to which reference has been 

 made. He practically accepts the classification proposed 

 by Abercromby and Hildebrandsson at the International 

 Conference held in Munich in 1891, and set forth in the 

 Cloud-Atlas of Hilderbrandsson, Koppen,and Neumayer. 

 The classification recognises ten different species ar- 

 ranged in five principal groups. The first group (A) 

 comprises the highest clouds in our atmosphere ; 

 the second group (B) includes clouds at a medium height, 

 and the third (C) low clouds. In the fourth (D) we have 

 clouds in ascending currents, and finally, (E) contains 

 the masses of vapour changing in form. In the first four 

 groups the letter (a) is used to distinguish the forms of 

 cloud usually accompanied by fine weather, and {b) for 

 those characteristic of bad weather. The following is the 

 grouping as given by Sig. Mannucci : — ■ 



Group A. 

 Clouds from medium altitudes up to an average of 

 9000 metres. 



1. Cirrus {a) 



2. Cirro-stratus {h) 



3. Cirro-cumulus 



Group B. 

 Clouds having altitudes from 3000 to 6000 metres. 



4. Alto-cumulus {a 



5. Alto-stratus {b) 



Group C. 

 Clouds the bases of which have altitudes from looo to 

 2000 metres. 



6. Strato-cumulus («) 



7. Nimbus {b) 



Group D. 

 Clouds on ascending columns of air, with bases about 

 1400 metres high, and summits from 3000 to 5000 metres. 



8. Cumulus (rt) 



9. Cumulo-nimbus {b) 



Group E. 

 Fogbanks up to about 1,500 metres. 



10. Stratus 



