209
The war and the political events of September 1870 interrupted the work and use
of this tower. Following the arrival of the Italians, however, the geodetic work was
resumed. Secchi was again invited to oversee the work, even though his state of
health did not allow him more active participation.
Being the new fundamental point for the calculation of longitudes given by the
small tower, it became necessary to connect it with the papal geodetic network as
determined from the geodetic baseline of 1855. To do this, by triangulation Mount
Mario was connected with a geodetic baseline about 510 m shorter than the original
one determined by Secchi. As Secchi himself pointed out during the measurement,
Endpoint A at Cecilia Metella was not a good fundamental trigonometric point due
to the absence of a good horizon, so he proposed an alternative point at the ruins of
Capo di Bove (41°50′54.5″N; 12°31′28.7″E datum WGS84/ETRF89) from which
the lap along the horizon was complete.
At this point the following memorial plaque was affixed (Fig. 12.4):
CAPO DI BOVE
NELL’ANNO MDCCCLV P. A. SECCHI
SULLA TRACCIA DEL P. BOSCOWICH
RIGOROSAMENTE MISURAVA LUNGO LA
VIA APPIA UNA BASE GEODETICA
E NELL’ANNO MDCCCLXX COLLO STABILIRE
PRESSO I DUE ESTREMI DI ESSA
QUESTO PUNTO TRIGONOMETRICO
E L’ALTRO ALLE FRATTOCCHIE COSTITUIVA
UNA NUOVA BASE SULLA QUALE FU
VERIFICATA LA RETE GEODETICA ITALIANA
ORDITA NELL’ANNO MDCCCLXXI DAGLI UFFICIALI
DEL CORPO DI STATO MAGGIORE PER LA
MISURA DEL GRADO EUROPEO
It should be noted that with this plaque the entire geodetic history of the Via Appia
Antica is recapitulated, recalling the measurements of the Jesuit fathers Boscovich
and Secchi, continuing through the measurement of the European Meridian Arc,
and ending in the first National Geodetic Network (1919).
The original tower was demolished shortly after 1878 in order to allow the
construction of a military fort (Campo Trincerato) as a part of the defense plan of
the city of Rome, moving the trigonometric point to the terrace of the nearby Villa
Manzi (today Villa Mellini, site of the Rome Observatory in the 20th century and
now the headquarters of the Istituto Nazionale di Astrofisica [INAF]). At the end of
the construction of the fort, the trigonometric point was reinstalled on the ground in
1882, and a tower was rebuilt in the same place that year. The new truncated conical
tower, made of brick, is only 7 m high. The entrance door is sited on the west side
with an internal spiral staircase that, immediately below the top floor, passes outside. Above the door is a travertine plaque with the inscription:
Osservatorio Astronomico
di Roma
PRIMO MERIDIANO
D’ITALIA
origine delle longitudini italiane
12 The Measurement of the Geodetic Baselines Along the Via Appia Antica
The war and the political events of September 1870 interrupted the work and use
of this tower. Following the arrival of the Italians, however, the geodetic work was
resumed. Secchi was again invited to oversee the work, even though his state of
health did not allow him more active participation.
Being the new fundamental point for the calculation of longitudes given by the
small tower, it became necessary to connect it with the papal geodetic network as
determined from the geodetic baseline of 1855. To do this, by triangulation Mount
Mario was connected with a geodetic baseline about 510 m shorter than the original
one determined by Secchi. As Secchi himself pointed out during the measurement,
Endpoint A at Cecilia Metella was not a good fundamental trigonometric point due
to the absence of a good horizon, so he proposed an alternative point at the ruins of
Capo di Bove (41°50′54.5″N; 12°31′28.7″E datum WGS84/ETRF89) from which
the lap along the horizon was complete.
At this point the following memorial plaque was affixed (Fig. 12.4):
CAPO DI BOVE
NELL’ANNO MDCCCLV P. A. SECCHI
SULLA TRACCIA DEL P. BOSCOWICH
RIGOROSAMENTE MISURAVA LUNGO LA
VIA APPIA UNA BASE GEODETICA
E NELL’ANNO MDCCCLXX COLLO STABILIRE
PRESSO I DUE ESTREMI DI ESSA
QUESTO PUNTO TRIGONOMETRICO
E L’ALTRO ALLE FRATTOCCHIE COSTITUIVA
UNA NUOVA BASE SULLA QUALE FU
VERIFICATA LA RETE GEODETICA ITALIANA
ORDITA NELL’ANNO MDCCCLXXI DAGLI UFFICIALI
DEL CORPO DI STATO MAGGIORE PER LA
MISURA DEL GRADO EUROPEO
It should be noted that with this plaque the entire geodetic history of the Via Appia
Antica is recapitulated, recalling the measurements of the Jesuit fathers Boscovich
and Secchi, continuing through the measurement of the European Meridian Arc,
and ending in the first National Geodetic Network (1919).
The original tower was demolished shortly after 1878 in order to allow the
construction of a military fort (Campo Trincerato) as a part of the defense plan of
the city of Rome, moving the trigonometric point to the terrace of the nearby Villa
Manzi (today Villa Mellini, site of the Rome Observatory in the 20th century and
now the headquarters of the Istituto Nazionale di Astrofisica [INAF]). At the end of
the construction of the fort, the trigonometric point was reinstalled on the ground in
1882, and a tower was rebuilt in the same place that year. The new truncated conical
tower, made of brick, is only 7 m high. The entrance door is sited on the west side
with an internal spiral staircase that, immediately below the top floor, passes outside. Above the door is a travertine plaque with the inscription:
Osservatorio Astronomico
di Roma
PRIMO MERIDIANO
D’ITALIA
origine delle longitudini italiane
12 The Measurement of the Geodetic Baselines Along the Via Appia Antica