Abstract
Angelo Secchi, in charge of the timekee** service at the Collegio Romano Observatory, promoted the adoption of mean time for Roman clocks and later saw the unification of the time measurement system in Italy.
His interest in timekee** was, however, wider and included historical studies in the field of archaeology.
Secchi had a great interest in public education and was a popular conference speaker: he was often asked to design and build sundials, where he would inserted analemmas to show the Equation of Time as a way of hel** people understand the transition to mean time. Today these instruments, located in many Italian regions, serve as a memorial to him.
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Notes
- 1.
The identification of these papers was made possible thanks to information found in: Chinnici, Ileana - Gramatowski, Wiktor, 2001. “Le carte di Angelo Secchi conservate presso l’archivio della P. Università Gregoriana. Un inventario inedito rivisitato”, Nuncius, XVI, 2, pp. 571–627.
- 2.
The railway network of the papal state, however, did not develop as the Pontiff had wished.
- 3.
In Rome one could already find pairs of clocks, one with Italian numbering and the other with the European one; the best known was situated on the face of the Vatican Basilica.
- 4.
The French or European system was introduced in Florence in 1749, in Parma in 1755, in Genoa in 1772, in Milan 1786, and Bologna in 1796.
- 5.
Piazzi G., “Sull’Orologio Italiano ed. Europeo. (On the Italian and European Clock),” Riflessioni, Palermo 1798.
- 6.
This publication was described and graciously provided by Mr. Renzo Lai, a former official of the Library of the Pontifical Gregorian University, who is very much thanked.
- 7.
The ritual of firing of the Castel San Angelo cannon created a certain fascination on the part of many Romans who would gather at various places in the city, clocks in hand, to wait for it.
- 8.
On the Eboli-Udine line, the legal mean time would have been that of Naples for the Eboli-Napoli segment, of Rome for the Naples-Roma-Foligno segment, Florence for Foligno-Firenze-Pistoia, Turin for Pistoia-Ferrara-Po, and Verona for Po-Rovigo-Udine.
- 9.
“Relazione fatta dal Ministro dei Lavori Pubblici a S. A. R. il Luogotenente Generale del Re in udienza del 22 settembre 1866, per proporgli l’adozione del tempo medio di Roma nel servizio dei convogli ferroviari, dei telegrafi, delle poste,” in Collezione Celerifera delle leggi, decreti, istruzioni e circolari pubblicate nell’anno 1866. (“Report made by the Minister of Public Works to S. A. R. the Lieutenant General of the King at the hearing of 22 September 1866, to propose the adoption of mean time Rome in the service of railways, telegraphs, post offices,” in the Celerifera Collection of laws, decrees, instructions and circulars published in 1866.)
- 10.
The development of the railway roads in Sicily was modest and without a continuity with the peninsula due to the lack of the southernmost section of the railway network. Under these conditions, there would have been no advantage to adopt the Roman timetable.
- 11.
Given his experience with geomagnetism, however, Secchi had lived experience of time on a global scale. By convention, these observers had adopted the mean time of Gottinga for the communication of experimental data (Tuscano 2020).
- 12.
Fabrica Et Usus Instrumenti Ad Horologiorum Descriptionem (The Construction and Use of Instruments to Describe Time) (1586) and Horologiorum nova descriptio (New Description of Time) (1599).
- 13.
Some sundials can still be seen on the facade; there is a darkroom meridian line in St. Luigi’s rooms and another in the Calandrelli tower. Francesco Carlini in 1843 recalled: “There was no shortage of transit instruments at the Roman College Observatory then; in order to adjust the clocks, every day at midday we used to observe a small meridian line inscribed on the floor and the wall of a room.”
- 14.
APUG, Secchi Archive, II n, Sulla divisione del Tempo (Tuscano 2012a). Thanks are given to Prof. Martin Maria Morales SJ and the officials of the Archive of the Pontifical Gregorian University for their great courtesy in allowing access to consult the manuscripts.
- 15.
Solar time has a variable rhythm throughout the year as a result of the eccentricity of the Earth’s orbit and the tilt of its axis on the orbital plane. Mean time moves at a constant rate. The two times differ at most by 16 min, agreeing on 4 days of the year: April 16, June 14, September 2, and December 26.
- 16.
Angelo Secchi, Memoria sopra alcuni lavori fatti al nuovo osservatorio del Collegio Romano durante il primo anno della sua erezione fino al 31 dicembre del 1855. (A record of some work done at the new observatory of the Roman College from the first year of its construction up to 31 December 1855.) This reference was identified by Maria Luisa Tuscano.
- 17.
Gaetano Moroni, Dizionario di erudizione storico-ecclesiastica (Dictionary of Ecclesiastical History Studies), 1854.
- 18.
This recent information was provided by Mrs. Anna Rita Pernasili and Dr. Giuseppe Anelli, officials of the Library and the Historical Archive of Sezze, respectively; great thanks to each.
- 19.
The restoration was carried out by Mr. Nicola Severino, scholar of the history of gnomonics.
- 20.
G. Straw, Il monastero benedettino di S. Giovanni Battista in Bovill e Ernica e i suoi 350 anni di vita, (The First 350 Years of the Benedictine Monastery of St. John the Baptist in Bovill and Ernica) Casamari 1980, p. 98. We sincerely thank Fr. Giovanni Magnante, pastor-archpriest of Boville Ernica, for having kindly identified and made available the documentary reference.
- 21.
Nicola Severino (www.nicolaseverino.it), Renzo Righi (Luci e Ombre, sulle ali del Tempo), Tuscano M.L. 2012b and 2020.
- 22.
G. Baptist, Mantovani, “Il Liceo Conti Gentili, Introduzione storica” in Il filo del Tempo: l’antico lab fisico Instrumenta selecta. (Mantovani R.ed.). Alatri 1996 (II rist.). We would like to thank Prof. Roberto Mantovani, Scientific Curator of Physics Cabinet: Urbinate Museum of Science and Technology, University of Urbino, for the courtesy of the providing this text.
- 23.
Andrewes,W. J. H. , Mantovani R., “La meridiana del Palazzo Conti Gentili,” in Il filo del Tempo: l’antico lab fisico instrumenta selecta. (Roberto Mantovani, ed.), op. cit.
- 24.
Analemmas refer to time lines that are not drawn but calculated for the longitude of Rome.
- 25.
Ibid.
- 26.
Chinnici Ileana (ed.), The total eclipse of the Sun of 1870 in Sicily, Letters of Pietro Tacchini to Gaetano Hunter. INAF- Astronomical Observatory of Palermo, 2008
- 27.
The history of these instruments has been preserved thanks to the work of Prof. M. Antonietta Guerrieri as part of the activities of the Tuscolana Association of Astronomy. Guerrieri A. 2014.
- 28.
Guerrieri, A, 2014.
- 29.
APUG, Secchi Archive, 82A.13 - Meridiana - notes (33 f.). The manuscript was identified and consulted in 2005 and 2011 by Maria Luisa Tuscano.
- 30.
The sundial was calculated for a latitude of 41° 47′ 5″; the secondary latitude is 41° 56′ 35″.
- 31.
APUG, 23.II. D, 64v. We thank Dr. Ileana Chinnici, historian of astronomy at the Palermo Astronomical Observatory, for graciously providing the documentary reference.
- 32.
Michael Chiodo, L’Accademia Cosentina e la sua Biblioteca, Cosenza, 2002, p. 112. The transcript of the Chronicle of Calabria was kindly made available by Dr. Michele Chiodo, whom we also thank for the search of the manuscript mentioned.
- 33.
Op. cit., p. 45.
- 34.
The late Prof. Edmund Marianeschi, known for gnomonic studies, reported this to the gnomonist Renzo Righi, who included a photo of the sundial in his Calendar for the Year 2003.
- 35.
APUG, Secchi Archive, 25.I - Note on the gnomon found in the excavations of Campomarzio (3 ff.)
- 36.
“(Boscovich) scrisse dotte illustrazioni intorno all’ obelisco di Cesare Augusto e ad un orologio solare trovato in un’antica villa scopertasi sul dosso del Tuscolo,” ([Boscovich] wrote learned illustrations concerning Caesar Augustus’s obelisk and a sundial found in an old villa discovered on the Tuscolo), Corniani G.B. – Ticozzi S., I secoli della Letteratura italiana, 1833.
- 37.
“(…) stimo più probabile l’idea di Boscovich che la lunghezza dei giorni e delle notti vi fossero indicate con le linee e non con i numeri (…) potevansi derivare dalla inesattezza della convenzione giuliana (…)” APUG, Secchi Archive, 25.I - Nota sul gnomone trovato negli scavi di Campomarzio (3 ff.). (Tuscano M.L. 2012a, Auber Alberi P.-Tuscano M.L. 2014).
- 38.
Luigi Vescovali, a well-known scholar of Archeology, was a member of the Pontifical Roman Academy of Archaeology.
- 39.
The dial is currently kept in Rome in the Collection of the National Roman Museum.
- 40.
Vitruvius in his treatise De Architectura names these instruments Viatoria pensilia».
- 41.
Atti dell’Accademia Pontificia dei Nuovi Lincei (Proceedings of the Pontifical Academy of New Lynxes), vol. IX, p. 37.
- 42.
A similar dial was made in Aiello del Friuli by Paolo Alberi and Roberto Pantanali.
- 43.
This method was useful for measuring the equinoctial time, used in Rome by astronomers and jurists (Nelle Antichità di Ercolano, Prefazione al vol, III, Note).
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Tuscano, M.L. (2021). Angelo Secchi and the Measurement of Time. In: Chinnici, I., Consolmagno, G. (eds) Angelo Secchi and Nineteenth Century Science. Historical & Cultural Astronomy. Springer, Cham. https://doi.org/10.1007/978-3-030-58384-2_15
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