17 - XIXth and XXth centuries - From cultural decadence to the building of the first dome in Loiano and the multi-mirror telescope.

After the death of Petronio Matteucci two directors were appointed in the space of a year, Girolamo Saladini from Lucca (1731-1813) and the above mentioned Giovan Battista Guglielmini of Bologna, both of whom, however, resigned.

Whether it was these resignations that triggered off a long period of cultural decadence at the Specola or whether it was the stagnating scientific atmosphere that rather triggered them, is hard to say. The fact remains however, as Michele Rajna (director from 1903 to 1920) would point out, that throughout the XIXth century there were numerous testimonials to the state of general abandon astronomy had fallen into in Bologna.

In 1802 Barnaba Oriani (1752-1832), director of the Specola in Milan, was sent to Bologna by order of the Italian Republic and found "Astronomy almost abandoned"; in 1840 the Viennese astronomer Karl Littrow (1811-1877) wrote of the Bolognese Specola: "on the whole it is comparable to an old building, which is of greater value to the archeologist than the astronomer"; the director of the Bordeaux Observatory, G. Rayet (1839-1906), describing in 1878 the Italian Specole for the French government, ended his chapter on Bologna with these words: "the Observatory is nothing more than a sort of Museum where the dust and rust corrode some of the historical instruments."(150) and a little later Pietro Tacchini (1838-1905) declared that "from 1874 on the abandoned state of the machinery and the ever increasing disorder in the Observatory have today made the instruments unuseable for actual astronomical observations", and expressed the hope that "the Observatory would not be forgotten and left in the indecent state it is in today." (151)

Numerous attempts were made by the local authorities, the national authorities and the astronomical community to revive the fortunes of Bolognese astronomy. Barnaba Oriani offered directorship of the Specola to Giuseppe Piazzi (1746-1826), already director of the Palermo Observatory, and J.G.F. Bohnenberger (1765-1831), astronomer from Tübingen, but neither accepted. Ottaviano Fabrizio Mossotti (1791-1863), mathematician, physicist and astronomer of great repute, did however accept, but his nomination by cardinal Opizzoni in 1835 was not ratified by the papal government because of his liberal ideas and participation in the Milanese conspiracies of 1821.

Thus, despite the presence at the Specola of talented astronomers such as Francesco Bertelli (1794-1844), Gaetano Ceschi (?-1845) and Domenico Piani (1782-1870), work was limited to compilation of the Ephemerides, publication of which stopped in 1844 on account of the rapid development of analogous publications edited in Berlin, London and Paris.

This long period of decadence was interrupted for a few years only during the brief directorships of Pietro Caturegli (1786-1833), Ignazio Calandrelli (1792-1866), Lorenzo Respighi (1824-1899) and Jacopo Michez (1839-1873).

The equipment was renewed to a some extent with the purchase of a movable quadrant by Mégnié (fl. end of XVIIIth century) who had won a prize at the Academié des Sciences in Paris [file 15], a transit telescope by Reichenbach, Utzschneider and Liebherr [file 20] - installed in the meridian Room in place of the age-old instrument by Sisson - and a meridian circle by Ertel & Sohn [file 22].

Although it required maximum stability, this well-made meridian circle was placed in the tower, 37 m off the ground, making it difficult to use and inaccurate; Respighi ended up using it exclusively as a zenithal instrument.

"Respighi - Giovanni Schiaparelli (1835-1910) would write - whose memory is cherished by all us Italian astronomers, managed, with the few means on hand in the then almost abandoned Observatory and with others he knew how to get hold of, to make some important discoveries: three comets are named after him (1862 IV, 1863 III and 1863 V, note by Rajna, op.cit.), and his theoretical research on Optics, his computations of latitude and the Earth’s magnetism, the beginning of his observations on the scintillation of stars, the early applications of his special method for observing zenithal stars by means of reflection in a mercury bath, his works on Bolognese Climatology, all show how much can be achieved with little equipment by a man truly animated by the spirit of science".

When in 1865 Respighi moved as director to the papal Campidoglio Observatory in Rome for not wishing to swear allegiance to the new King of Italy, Alessandro Palagi (1811-1889) from Bologna and Antonio Saporetti (1821-1900) from Ravenna took over provisionally until the nomination of the above mentioned Paduan Jacopo Michez who worked with celestial mechanics (with several studies on the perturbative effects of the planets on the Biela’s Comet), the Earth’s magnetism and its variations during solar eclipses. His early death left the position of director at the Specola open once more.

"Astronomy remained represented in Bologna - Rajna was to write (152) - by the forceful, original (if not completely composed and ordered) genius and vast learning of Quirico Filopanti, who never belonged to the Observatory and who after 1864, for reasons that do him honor, was never to hold an official position at the University again".

Mechanic and physicist, Giuseppe Barilli (1812-1894) - he himself chose the pseudonym Quirico Filopanti in 1837 - had taken part in the Constituent Assembly of the Roman Republic and Garibaldi, who he had fought with in Trentino, called him his "teacher and professor of the infinitive". With the fall of the Republic, he took refuge in England from where he returned in 1861 to take up the chair of Mechanics and Physics at the University of Bologna which he had been awarded back in 1848. He was however removed from the chair again in 1864 for refusing to swear an oath to the new government.

The Specola was reduced, at the turn of the century, to making just meteorological observations until Michele Rajna, disciple of Schiaparelli, was appointed as director.

"Nominated director and holder of the chair of Astronomy in February 1903 - Rajna wrote to the Rector of the Royal University of Bologna in 1906 - I have naturally studied conditions in the Observatory from close up...the idea of new equipment in the old tower is absolutely out of the question...But if we want - as we should want in Bologna - a real astronomical Laboratory, a Specola, that is, where truly useful observations can be made and scientific progress kept abreast of, the present seat must be abandoned". The new seat suggested by Rajna was Villa Aldini, 250 m above sea-level. The plan, begun with the purchase of a transit telescope by Bamberg, was never brought to a conclusion because of the early death of Rajna in 1920.

Rajna’s successor was his assistant since 1912, Guido Horn-d’Arturo (1879-1967) who pressed ahead with his predecessor’s plan to build an observational station on the Bolognese Appenines.

In 1915 Adolfo Merlani, keen amateur astronomer and already assistant to the chair of Mathematical Analysis, had donated one and a quarter hectares of his land on Monte Donato (240 m above sea level) to the University of Bologna for the purposes of building there an observational station. Unfortunately, the land had been the site of ancient fortifications and was hence prone to subsidence: the project was therefore abandoned. In 1925, however, Merlani’s widow left the Observatory the substantial sum of three hundred thousand lire to buy a large telescope in honor of the memory of her husband.

Horn-d’Arturo thus began negotiations with the company Karl Zeiss of Jena for the construction of a top quality reflector telescope with a 60 cm diameter (F/3.5). The instrument reached Bologna in July 1933 in nine boxes weighing a total of 60 quintals.

In the meanwhile the University administration had bought two hectares of land on mount Orzale, 800 m above sea level, near the village of Loiano, some 40 km from Bologna. On November 15, 1936, the new observational station was inaugurated and on December 21 of the same year the first photograph with the new telescope was made.

Before the Zeiss reflector a small 15 cm equatorial telescope by Watson and Conrady had been bought, later used as guide telescope for the Zeiss reflector, and an astrograph with a 14 cm aperture. The observatory had in its possession, from the end of the previous century, a telescope by Steinheil with a 162 mm aperture and focal length of 260 cm [file 48], provisionally installed on a wooden frame by Tacchini who had used it to observe the transit of Venus across the solar disc in India. The lens of this telescope was to be fitted on the guide telescope of the Zeiss refractor.

Besides the complete revitalization of the Bolognese Specola and its return to the international research circuit, another undisputed achievement of Horn-d’Arturo was the idea of obviating the difficulties of working optically on large surface areas by developing a "multi mirror" telescope. This was essentially the same technique used by the Americans in recent years with the Multi Mirror and the Keck Telescopes, producing a large reflecting surface area using numerous small "mirrors" of identical spherical curvature (153).

The first multi mirror designed by Horn-d’Arturo had a 1 m aperture and 10.5 m focal length and was placed in the top room of the tower - the present "Turret Room" in the museum - in line with a 1.2 m hole made in the roof back in 1725, which was used for carrying out zenithal observations with the long telescope tubes.

To build the second multi mirror, comprising 61 mirrors, for a total aperture of 180 cm, a hole was drilled through four floors of the tower, under the small west dome where the meridian circle of Ertel & Sohn was lodged, thus obtaining a 24 m high and 2 m diameter cylinder.

Using this instrument - recently put back to its original place [file 50] - and with the help of Giovanni Battista Lacchini and some technicians of the Specola, Aldo Galazzi and Orfeo Fusi Pecci, some tens of thousands of film exposures were obtained, carrying out a systematic survey of the zenith sky in Bologna. In the 6 minutes 45 seconds the plate - usually a "Cappelli Ultrasensibile" - was able to follow the motion of the sky, it was possible to photograph stars beyond the eighteenth magnitude, thus leading to the discovery of ten or so new variables.

Among the commendable work done by Horn-d’Arturo, mention should be made of his contribution to the library, contemporary and historical - which he enlarged considerably -, his rescuing of a large part of the historical instrumentation, and his founding of the astronomical journal Coelum, the first issue of which came out in January 1931 and which closed after 55 years in 1986.

With the end of Horn-d’Arturo’s directorship in 1954, we come to the end of our history, being too close to the contemporary and the lives of the present authors to write anything other than a chronicle.

  1. - C. André, G. Rayet, A. Angot: 1878, L'astronomie pratique et les Observatoires en Europe et en Amérique. Cinquième partie: Observatoires d'Italie, Gauthier-Villars, Paris, pp. 67-84.
    "l'Osservatorio non è più che una specie di Museo dove la polvere e la ruggine corrodono alcuni strumenti storici."
  2. - M. Rajna: 1906, Sulle condizioni dell'Osservatorio della R. Università di Bologna e idee fondamentali per il progetto di una nuova specola da stabilirsi sulla collina dell'Osservanza presso Bologna, Relazione al Rettore della R. Università di Bologna, Bologna.
  3. - G.Parmeggiani, F.Bònoli: 1995, Quirico Filopanti: una singlare figura di astronomo nella Bologna dell'Ottocento, in Atti del Convegno Gli Osservatori Astronomici a le Istituzioni Astronomiche in Italia, Società Astronomica Italiana, in stampa.
    M. Rajna: op. cit., p. 12.
  4. - G. Horn-d'Arturo: 1932, Strumenti e progressi dell' Astronomia, Coelum, II, p.25
    G. Horn-d'Arturo: 1932, Telescopi dell'avvenire, Coelum, II, p.49.
    G. Horn-d'Arturo: 1932, Telescopi dell'avvenire e specchi a tasselli, Coelum, II, p.121.
    G. Horn-d'Arturo: 1935, Il cielo fotografato con lo specchio a tasselli, Coelum, V, p. 233.
    G. Horn-d'Arturo: 1952, Lo specchio a tasselli dell'Osservatorio astronomico universitario di Bologna, Coelum, XX, p.65.
    G. Horn-d'Arturo: 1955, Il compiuto specchio a tasselli di metri 1,80 d'apertura collocato nella torre dell'Osservatorio astronomico universitario di Bologna, Coelum, XXIII, p. 65.
    L. Jacchia: LV 1978, Forefathers of the MMT, Sky and Telescope, p. 100.