247
degrees East Greenwich, which will be named Central European time. The decree
also stipulated that the timetable for each day’s rail service will be set to run from
midnight to midnight.
The new timetable rules for the railways gradually entered into civil use, and in
this way, Italy no longer referenced the average time of Rome but that of the meridian that crosses the crater of Etna and Termoli. For this reason, Central European
time is sometimes referred to as Mount Etna time. However, Father Angelo Secchi,
who died in 1878, would not witness these last stages of mean time reform.
11
15.3 The Study of “Gnomonics” in the Society of Jesus
Among the Jesuit scholars interested in the study of sundials or “gnomonics” – or
Scioterica, to give it its ancient name – there are so many figures of great importance that it is difficult to do justice to the issue in this short space. It’s worth taking
a brief look at three, Clavius, Kircher, and Ximenes, because they are emblematic
of the three centuries (sixteenth–eighteenth) that preceded the activities of Father
Secchi. One should acknowledge, however, figures such as Matteo Ricci, Prospero
Intorcetta, Mario Bettini, Ruggiero Giovanni Boscovich, and others who also played
a significant role in the topic.
The use of sundials was practiced in the Middle Ages by monastic orders for the
observance of the Divine Office and for the ordering of their ministries. It subsequently entered into the curriculum of study of other religious orders, as a kind of
applied mathematics; in Jesuit colleges, the teaching of mathematics became a part
of the Ratio Studiorum in 1599 (Baldini, Chap. 2 in this volume). The theory of
sundials evolved from the sixteenth to the eighteenth century, during which time the
geometric method was replaced by trigonometric calculations with the use of
logarithms.
For the German Christoph Klau (1537–1612) – better known as Clavius – gnomonics was a discipline in which geometry opened up formulations of articulated
projections, starting from the Analemma of Ptolemy. Starting in 1564, Clavius
taught mathematics at the Roman College, writing the monumental and complex
work Gnomonices Libri Octo, published in 1581, as well as two supplementary
texts which presented new methods and described some tools for making sundials.
12
This combination of theoretical and practical texts took on a particular educational
significance, because it anticipated a type of experimental teaching that would be
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).
15 Angelo Secchi and the Measurement of Time
degrees East Greenwich, which will be named Central European time. The decree
also stipulated that the timetable for each day’s rail service will be set to run from
midnight to midnight.
The new timetable rules for the railways gradually entered into civil use, and in
this way, Italy no longer referenced the average time of Rome but that of the meridian that crosses the crater of Etna and Termoli. For this reason, Central European
time is sometimes referred to as Mount Etna time. However, Father Angelo Secchi,
who died in 1878, would not witness these last stages of mean time reform.
11
15.3 The Study of “Gnomonics” in the Society of Jesus
Among the Jesuit scholars interested in the study of sundials or “gnomonics” – or
Scioterica, to give it its ancient name – there are so many figures of great importance that it is difficult to do justice to the issue in this short space. It’s worth taking
a brief look at three, Clavius, Kircher, and Ximenes, because they are emblematic
of the three centuries (sixteenth–eighteenth) that preceded the activities of Father
Secchi. One should acknowledge, however, figures such as Matteo Ricci, Prospero
Intorcetta, Mario Bettini, Ruggiero Giovanni Boscovich, and others who also played
a significant role in the topic.
The use of sundials was practiced in the Middle Ages by monastic orders for the
observance of the Divine Office and for the ordering of their ministries. It subsequently entered into the curriculum of study of other religious orders, as a kind of
applied mathematics; in Jesuit colleges, the teaching of mathematics became a part
of the Ratio Studiorum in 1599 (Baldini, Chap. 2 in this volume). The theory of
sundials evolved from the sixteenth to the eighteenth century, during which time the
geometric method was replaced by trigonometric calculations with the use of
logarithms.
For the German Christoph Klau (1537–1612) – better known as Clavius – gnomonics was a discipline in which geometry opened up formulations of articulated
projections, starting from the Analemma of Ptolemy. Starting in 1564, Clavius
taught mathematics at the Roman College, writing the monumental and complex
work Gnomonices Libri Octo, published in 1581, as well as two supplementary
texts which presented new methods and described some tools for making sundials.
12
This combination of theoretical and practical texts took on a particular educational
significance, because it anticipated a type of experimental teaching that would be
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).
15 Angelo Secchi and the Measurement of Time