September, 1903.] 



KNOWLEDGE. 



211 



the sun no lon<^er entered the sign Aries on the orthoilox 

 21st of March ; a circumstance which, as seriously affecting 

 the date of Easter, gave Gregory the opportunity of 

 conferring a lasting eclat on his pontificate by undertaking 

 the long-desired reform of the calendar. This reform, 

 projected by the Neapolitan physician and astronomer, 

 Lilio, and aftei-warJs more fully demonstrated by the 

 Jesuit, Clavius, was established by papal brief in 1582, 

 but so strong was the feeling against the measure in all 

 countries not adhering to the Church of Home that it 

 was not adopted by Germany until after the energetic 

 representations of Leibnitz and others in 1700, nor by 

 England luitil more than half a century later, when its 

 introduction met with the greatest opposition, while 



Fio. 1.— Til 



the Vatican Observatory. 



Russia disregards it even to-day. The significant appear- 

 ance on the official seal of the Vatican Observatory 

 of the Ram's Head, symbolical of the sun's position 

 at the vernal e(|uiuox, still serves to commemorate the con- 

 nection between the Gregorian Tower and the Gregorian 

 Calendar. Though, from its height of 73m. above sea- 

 level, well enough adapted for the astronomical work of 

 those times, the " Tower of the winds " did not long enjoy 

 its reputation as an observatory, and it was only towards 

 the end of the eighteenth century that it began, in a 

 measure, to regain the importance of its earlier days. 

 Meteorology, however, rather than astronomy, now formed 

 the chief study, for it had been found that, as the vast 

 dome of St. Peter's somewhat impeded the view towards 

 the south, the site was less favounxbly placed for astro- 

 nomical work than that occupied by the observatory of the 

 Collegio Romano, erected in 1787, and rendered famous 

 through the labours of De Vico and his illustrious 

 successor Secchi. Nevertheless, for some thirty years after 

 1789 the Vatican Observatory continued to display 

 considerable activity in observational work under Gilii, but 

 after his death in 1821 it again fell into disuse, the instru- 

 ments liecoiuing gradually dispersed and the place itself 

 deserted, until, after the political events of 1870, when the 

 Italian troops took formal possession of the Eternal City, 

 and Pius IX. entered u[ion his self-im|)0sed imprisonment 

 in the Vatican, the locale of the observatory, owing to the 

 e.xigencies of space, was finally transformed into dwelling 

 apartments. 



But in spite of this fall, the strangely eliequered fortunes 

 of the venerable institution were not to end here, for the 

 observatory was soon to enter upon the last and most 



active period of its existence — that which recognises in it 

 the well-kno^vTi and well-ecjuipiped Specola Vaficana of 

 to-day. The immediate cause of this resuscitation was the 

 scientific exhibition held at Rome in 1888 to commemorate 

 the Jubilee of Leo XIII. At its close the late Father 

 Denza, whose name had been for many years before the 

 scientific world, suggested to the Pope that the collection 

 of instruments forming part of the exhibition should be 

 made use of t« reconstitute the Vatican Observatory. 

 This project not only met the immediate approval of 

 Leo XIII., hira.self a mathematical prizeman of earlier 

 years, but was so enthusiastically carrieil through 

 that by the summer of 1889 Denza had nearly all his 

 instruments installed, and was able to attend the Inter- 

 national Photographic Congress at Paris as representative 

 of the Vatican Oljservatory, and to claim for the newly 

 reconstructed institution a place among the eighteen great 

 observatories taking part in Admiral Mouchez's grandiose 

 scheme of charting the heavens. Under the formal 

 directorship of Denza the observatory was now equipped 

 with all the most modern meteorological, magnetic, and 

 seismological instruments, many of them being the first to 

 be introduced into an Italian observatory, while its purely 

 astronomical department was enriched by the addition of 

 the astrographic telescope constructed in Paris by the 

 Brothers Henry, and mounted by Gautier, of the Paris 

 Observatory. This instrument, which, like its Paris 

 congener, is mounted on the so-called English system, is 

 carried on piers of white Carrara marble, and consists 

 of the usual pair of telescopes contained in a rectangular 

 case of metal, the photographic telescope having the 

 regulation aperture of 33 cm. to a focal length of 3'43 m., 

 and the visual one an aperture of 20 cm. to 360 m. focal 



Fio. 2.— The Leonine Tower. 



distance. It was placed in position in May, 1891, on the 

 strongest of the towers belonging to the ancient Leonine 

 wall mentioned above. 



Curious as was the anachronism of fitting one of the 

 most specialized products of the nineteenth century to a 

 structure dating from the ninth, the old Leonine tower 

 nevertheless proved itself admirably adapted for the novel 

 purpose to which it was put ; for situated as it is on tlie 

 summit of the Vatican hill some 400 m. distant from the 

 Gregorian tower, with which it is in telephonic communi- 

 cation, and, with its colossal walls of over 4 m. tliickuess, 

 almost a monolith in strength, it unites iu the happiest 

 m;uiner the elements of isolation and soliditv so essential 



