“Section of the Roman College of the Observatory”

“Descrizione del nuovo Osservatorio del Collegio Romano”
Angelo Secchi
Memorie dell'Osservatorio del Collegio Romano 1852-1855
Tipografia delle Belle Arti, Roma, 1856
Tavola II
Engraving, 490 x 475 mm
Library of INAF-Astronomical Observatory of Capodimonte, Naples

Recalled to Rome with the post of the direction of the Roman College Observatory, Secchi was concerned to find a seat more suitable for the observatory. He kept the meteorological observatory in the original headquarters of the Calandrelli Tower (Figure 1), and he moved the astronomical instrumentation to new premises, created on purpose on the roof of the adjoining church of St. Ignatius, exploiting the four sturdy pillars intended to support the dome, that was never built.
Secchi enriched the existing instrumentation with a remarkable 25 cm opening Merz telescope (in the upper right corner of the image), purchased with a legacy in favor of his assistant Paolo Rosa; In addition, he set up a geomagnetic observatory in rooms suitably built away from metallic elements.
The section of the new observatory, depicted here, shows the arrangement of the halls. On the planimetry (Figure 2), the rooms are indicated with the following numbers, respectively :
A – Connecting room with the spiral staircase in communication with the College
B-Library
C-central stairway accessing the domes
M – Meridian Room
E-room of the equatorial
F, G-hallway rooms
H – Geomagnetic cabinet
Note, in the section of the plant, the bust of Pius IX, placed on the top of the central staircase, as a sign of gratitude to the pontiff who had supported, also economically, the realization of the new observatory of the Roman College.
The idea of Secchi was to dedicate the observatory mainly to physical astronomy: this line of research, absolutely innovative for those times, was congenial not only to his formation as a physicist, but also to the reduced economic resources-which do not allowed the purchase of powerful telescopes- and to the rhythms of the staff. Since the latter was made by religious, the personal commitments of prayer and apostolate had to be conceiled with astronomical work, so the series or regular observations required in other disciplines, such as astrometry and celestial mechanics, could not be ensured.
The impulse given by Secchi to the new observatory (Figure 3) made it one of the first and most active centers of astrophysics in the world.

Ileana Chinnici, INAF-Osservatorio Astronomico di Palermo