Josef Stepling, a mathematician, physicist and astronomer, as well as a Catholic priest, is inextricably linked with Clementinum. Both with the library and the local meteorological station, where he began his systematic measurements in 1772, i.e. observations of temperature, barometric pressure and precipitation measurements. These measurements continue to this day and are among the oldest continuous meteorological observations in Central Europe.
Soon after his father’s death, Stepling moved with his mother from Regensburg to Prague, where he studied at a Jesuit school. Even then, mathematics and physics were among his favourite courses. In 1733 Stepling entered the Jesuit order. He completed his novitiate in Brno, philosophical studies in Olomouc, and theology in Prague. In 1747 he was ordained a priest and began to lecture on mathematics and physics, already according to Newton.
What followed was a steep career as a scholar and reformer of new educational methods, especially university ones, supported by Empress Maria Theresa. As early as 1753, Stepling became “royal director” of studies in mathematics and physics at the philosophical faculty of Charles-Ferdinand University in Prague, and was therefore retained as a professor there even when the Jesuit order was abolished (1773).
The Clementinum in Prague became the centre of his research. Already in 1751, he was appointed the first director of the Clementinum Observatory, as he was the most involved in its construction and equipping. He purchased a number of contemporary instruments and other equipment for the operation of the observatory from his inheritance, or the sum of 4000 gold coins.
Stepling’s first and most important scientific topic was the determination of the longitude of Prague, thanks to the Berlin Academy project for a new geographical map of Germany (1748). In the following decades, Stepling continued his astronomical calculations in the already fully equipped Clementinum Observatory and increasingly focused on the precise calculation of the distance of Prague from the zero meridian (then passing through the island of Ferro in the Canary Islands). He also reports on the geographical location of Prague in 1763, when he publishes a volume of small mathematical, physical and astronomical papers with a number of new data.
Stepling’s scientific interests included protection against lightning and earthquake research, specifically the Lisbon earthquake of 1755, and later (thanks in part to it) the geological changes of the springs in the north Bohemian town of Teplice. His aim was to trace the causes that trigger earthquakes.
Before his death, Stepling bequeathed about 600 volumes of books to the university library in Clementinum, which is also reflected in the inscription on the local marble monument. It includes a cupid by Ignaz Platzer after Q. Jahn from 1780. The inscription reads:
IOSEPHI.Steplingi. / DE.literis. / ET. / hac.bibliotheca. / insigniter.meriti. / memoriam.et.exemplum. / posteris.commendat / maria.theresia.avg. / obiitxi.ivl.mdcclxxviii*
Stepling became a very active member of the Society for Ploughing and Liberal Arts in Bohemia, founded by M. Teresa in 1767, as well as of the Private Learned Society for the Development of Mathematics, Patriotic History and Natural Science (1773). In the new spirit of the development of the sciences, he also trained a number of his pupils who continued his legacy, especially Jan Tesánek, Antonín Strnad, Stanislav Vydra and František Josef Gerstner. The asteroid 6540 was named in honour of Josef Stepling.
Note (translation)*
[The memory and example of Joseph Stepling, who made an outstanding contribution to writing and this library, is bequeathed to posterity by the noble Maria Theresa. He died on July 11, 1778].
Smolka, J. – Vackářová, J.: Josef Stepling (1716–1778) v jeho biografiích a bibliografiích. Praha 2018.
Smolka, J. – Ullmaier, H.: Neznámé listy Josefa Steplinga Maximilianu Hellovi. AUC – HUCP, 2017, LVII/2, s. 79–89.
Smolka, J. – Šíma, Z.: Josef Stepling (1716–1778) a určování geografické délky Prahy. AUC – HUCP, 2017, LVII/2, s. 91–106.
Smolka, J.: Josef Stepling a Royal Society ještě jednou. AUC – HUCP, 2019, LIX/1, s. 161–174.
Stepling Josef. Ottův slovník naučný: illustrovaná encyklopaedie obecných vědomostí. Dvacátýčtvrtý díl, Staroženské-Šyl. Praha 1906, s. 107.
