“Vue général de l’observatoire de Greenwich”

"(côté ouest)"
S. Laplante Sc., Perot
L’astronomie pratique et les observatoires en europe et en Amerique. Première partie. Angleterre
par C. André, G. Rayet
Paris, Gauthier-Villars, 1874
Tav. 2
111 x 177 mm
Library of INAF - Astronomical Observatory of Capodimonte, Naples

On August 30, 1858, Angelo Secchi left France for England. His first interest was directed towards the observatory of Greenwich, where George Biddell Airy showed him the last purchase of the Institute: a 32 cm diameter Merz refractor, equipped with all the most modern functionalities. However Secchi, who had more modest instrumentation, deemed the large telescope as a “unattractive and tasteless giant”. Russell Henry Manners, secretary of the Royal Astronomical Society, invited Secchi to visit the Crystal Palace (Figure 1), venue of the first Universal Exposition of 1851, the described by the astronomer as “spectacular wonder, wider than St. Peter[cathedral] and long three times longer than it. ”
One of the most interesting encounters had by Secchi in London was with Warren De la Rue, pioneer of astronomical photography, who described as “a highest engineer, a perfect chemist [and a] millionaire with pounds… So you can do astronomy without bothering anybody, and photographs without any inconvenience. ” He had made a beautiful series of “photographic images of some fixed stars, those of the planets Jupiter, Saturn and Mars [obtaining] the stereoscopic evidence of the abovementioned planets. The Moon was portrayed by him both in its various phases and stereoscopically “(Figure 2). Secchi was particularly struck by the excellent instrumentation owned by De La Rue, especially by the magnificent 33 cm equatorial telescope with a perfect clockwise movement. But the attention of Secchi was attracted mainly by the photographic techniques used by De la Rue , especially the use of the collodium solution introduced in the process of photographic film’s development. From these scientific conversations Secchi obtained great ideas and new stimuli to pursue his research in the field of astrophotography with more tenacity.
Secchi’s voyage continued by visiting the laboratory of Charles Wheatstone, who showed him his new model of telegraph and then the observeratories of Stonyhurst College, Dublin and Oxford. After purchasing scientific equipment and the large Fresnel lenses for the lighthouses of the ports of Ancona and Civitavecchia, on September 23, Angelo Secchi was in France again, and from there he returned to Rome.

Mauro Gargano, INAF-Osservatorio Astronomico di Capodimonte
Valeria Zanini, INAF-Osservatorio Astronomico di Padova

Bibliography
Borlinetto L. (1868), Trattato generale di fotografia, Padova, Stabilimento Nazionale di P. Prosperini;
Chinnici I. (2018), Deconding the stars, in press;
Secchi A. (1858), Diario, APUG.