176
Secchi between 1855 and 1867 at the Collegio Romano Observatory, in Rome, was
one of the most complex and probably the most spectacular one.
At the beginning, Secchi just developed a recording balance barometer; but over
the years he added to it a metallic wire thermometer, a wind vane with an anemometer, a pluviometer, an indicator of the hour and duration of rain, and finally a psychrometer. The psychrometer, with two moveable contacts periodically touching the
mercury columns of the wet and dry thermometer and with a recording trolley, was
one of the most delicate and complex organs of the meteorograph. The data from
these instruments were recorded by a series of articulated arms with pens on two
sheets of paper fixed to a pair of moveable boards. On one of them, the data were
recorded for 2 days, on the other for 10 days. A large clockwork mechanism moved
the board as well as the recording trolley of the psychrometer. Exploiting wellknown telegraphic technology, the indications of the wind vane and of the anemometer (which were installed on the roof of the observatory) were transmitted via an
electric circuit to a series of electromagnets counters and the recording apparatus of
the meteorograph; likewise, the rain indicator and the psychrometer worked via an
electrical system.
The original meteorograph, which was continuously improved, was installed at
the new Collegio Romano Observatory on the roof of St. Ignatius Church in Rome
(see Altamore et al., Chap. 1, in this volume). Having obtained the support of Pope
Pius IX, Secchi decided to present a final and lavishly constructed version of the
apparatus to the 1867 Paris Universal Exhibition. It became an emblem of Church’s
interest in modern science. The instrument was made by the Roman instrument
maker Brassart; Emilio Brassart and his brother, Ermanno, were active in Rome in
the second half of the nineteenth century and specialized in the construction of
meteorological and seismological apparatus. The clockwork came from the workshop of the famous Parisian clock maker Constantin Louis Detouche (1810–1889).
The meteorograph was considered a technical marvel and enjoyed a great success in Paris. Secchi was awarded a gold medal by the specialized jury and he also
received a monetary prize (Chinnici 2019: 125–133) (Fig. 10.1)
This apparatus was described and illustrated in many scientific treatises, booklets, and articles (Brenni 1993a). Secchi hoped that his meteorograph could be
installed in a network of meteorological observatories, all recording the same
parameters in the same way. But in spite of the ingenuity of the meteorograph, a
major obstacle hindered its wider distribution: it was very expensive. The model
displayed in Paris cost 18,000 gold francs (about $3460 US), certainly a huge sum
of money in those days.
In order to remedy this problem, in 1872 Ermanno Brassart made various cheaper
versions of the apparatus, encouraged by Secchi himself. Certainly Secchi and
Brassart hoped that the lower price could convince more potential clients to acquire
a meteorograph. A booklet published by Brassart described the modifications and
proposed the following models (Brassart 1872) (Fig. 10.2):
(a) A first meteorograph almost identical to the one of the 1867 exhibition and with
the same recorders (11,500 lire; because of the convention called the Latin
P. Brenni
Secchi between 1855 and 1867 at the Collegio Romano Observatory, in Rome, was
one of the most complex and probably the most spectacular one.
At the beginning, Secchi just developed a recording balance barometer; but over
the years he added to it a metallic wire thermometer, a wind vane with an anemometer, a pluviometer, an indicator of the hour and duration of rain, and finally a psychrometer. The psychrometer, with two moveable contacts periodically touching the
mercury columns of the wet and dry thermometer and with a recording trolley, was
one of the most delicate and complex organs of the meteorograph. The data from
these instruments were recorded by a series of articulated arms with pens on two
sheets of paper fixed to a pair of moveable boards. On one of them, the data were
recorded for 2 days, on the other for 10 days. A large clockwork mechanism moved
the board as well as the recording trolley of the psychrometer. Exploiting wellknown telegraphic technology, the indications of the wind vane and of the anemometer (which were installed on the roof of the observatory) were transmitted via an
electric circuit to a series of electromagnets counters and the recording apparatus of
the meteorograph; likewise, the rain indicator and the psychrometer worked via an
electrical system.
The original meteorograph, which was continuously improved, was installed at
the new Collegio Romano Observatory on the roof of St. Ignatius Church in Rome
(see Altamore et al., Chap. 1, in this volume). Having obtained the support of Pope
Pius IX, Secchi decided to present a final and lavishly constructed version of the
apparatus to the 1867 Paris Universal Exhibition. It became an emblem of Church’s
interest in modern science. The instrument was made by the Roman instrument
maker Brassart; Emilio Brassart and his brother, Ermanno, were active in Rome in
the second half of the nineteenth century and specialized in the construction of
meteorological and seismological apparatus. The clockwork came from the workshop of the famous Parisian clock maker Constantin Louis Detouche (1810–1889).
The meteorograph was considered a technical marvel and enjoyed a great success in Paris. Secchi was awarded a gold medal by the specialized jury and he also
received a monetary prize (Chinnici 2019: 125–133) (Fig. 10.1)
This apparatus was described and illustrated in many scientific treatises, booklets, and articles (Brenni 1993a). Secchi hoped that his meteorograph could be
installed in a network of meteorological observatories, all recording the same
parameters in the same way. But in spite of the ingenuity of the meteorograph, a
major obstacle hindered its wider distribution: it was very expensive. The model
displayed in Paris cost 18,000 gold francs (about $3460 US), certainly a huge sum
of money in those days.
In order to remedy this problem, in 1872 Ermanno Brassart made various cheaper
versions of the apparatus, encouraged by Secchi himself. Certainly Secchi and
Brassart hoped that the lower price could convince more potential clients to acquire
a meteorograph. A booklet published by Brassart described the modifications and
proposed the following models (Brassart 1872) (Fig. 10.2):
(a) A first meteorograph almost identical to the one of the 1867 exhibition and with
the same recorders (11,500 lire; because of the convention called the Latin
P. Brenni