Mailhat, Paris 1916

9 cm aperture
2 meters focal length

INAF – Rome Astronomical Observatory, n.i. M0019

Interest in solar physics among the Roman astronomers continued, keeping in the traditions started by Secchi and Respighi and continued by Tacchini, who was the Director of the Collegio Romano Observatory after Secchi, from 1879 to 1902. The present photographic camera was provided with four objectives and filters, which made possible to obtain four images of solar photosphere, in different wavelengths. It was often also used during solar eclipses, including probably the total one of 29 May 1929, which was visible from Africa. On that occasion, in the expedition guided by Arthur Eddington (1882- 1944), it was first evidenced deflection of rays from stars, due to gravitational effects by the Sun, caused by their passage near it: it was one of the first experimental proofs of the theory of General Relativity. The Parisian-based Mailhat firm, which operated between the end of 19th century and the first decade of 20th century, produced large refracting telescopes, which were installed in various European and American observatories, but also small portable and amateur-type instruments. It is worth mentioning the fact that in the second decade of 20th century, the Berlinbased Bamber-Askania firm produced a very sophisticated camera, provided with a coelostat, an objective of 16 cm aperture and a focal distance of almost 5 m, which allowed photographic images to be taken on 13×18 cm plates. Only two specimens of this camera were made, one of which was acquired by the Campidoglio Observatory in about 1920. Moved to the Monte Mario Observatory in 1938, the telescope worked for several decades until the late 60’s, and was engaged in taking daily shots of the solar photosphere, which today constitute a huge scientific archives, kept at the Rome Astronomical Observatory. [a.a., m.f., f.p.]

Bibl.: Horn D’Arturo, Taffara 1925; Wolfschmidt 2012.