Sky & Telescope - January 2019 - 69

personal effort to make sure his daughter received comprehensive instruction. He encouraged her interest in astronomy
from a very young age, and later she had the opportunity to
study with and, ﬁnally, become an assistant to, the peasant
astronomer Christoph Arnold of Sommerfeld. Arnold worked
in Leipzig, where he observed the Great Comet of 1686
with Gottfried Kirch. Winkelmann met Kirch, who would
soon become her husband, while she was acting as Arnold's
observing assistant.
Gottfried Kirch was born during the Thirty Years' War, the
son of a tailor. He lived a quite restless childhood and probably didn't get a degree, but he had good academic contacts.
For example, Erhard Weigel, professor of mathematics at the
University of Jena from 1653 to 1699, recommended him
to the Polish astronomer Johannes Hevelius. Thanks to this
endorsement, Kirch worked in Danzig, at Hevelius's wellequipped private observatory, for a short time in 1674. Before
reaching tenure as full astronomer in Berlin in 1700, Kirch
supported himself with teaching and the production of books
of observations and calculations, but also through the preparation of calendars. The latter is a key point in this story.

PUBLIC DO M AIN

Kalenderpatent
Calendar production was a major responsibility for astronomers in the late 17th to early 18th century. In addition to
including information about feast days (religious holidays),
calendars were replete with information on celestial objects,
including lunar phases and positions of major stars and
planets. Gottfried Kirch was the widest-read calendar maker
of his generation, publishing up to 13 calendars at a time,
including eventually the ofﬁcial state calendar.
The task of producing the state calendar was tied to an
appointment called a Kalenderpatent, a position that had been
expressly created by Frederick III, Prince-elector of Brandenburg, with an edict issued on May 10, 1700. The act followed
the decision of German Protestant states to introduce a new
and improved calendar beginning in 1700; the calendar,
which was to be calculated by qualiﬁed astronomers, would
be identical in practice to the Catholic Gregorian calendar,
with the exception of the date of Easter. This edict thus introduced a monopoly for calendar production in the Electorate
of Brandenburg, and later in Prussia, and allowed for the
imposition of a "calendar tax," the proceeds of which were
used to pay the astronomers and other members the Royal
Prussian Academy of Sciences in Berlin, which was founded
on July 11th of the same year. Not coincidentally, Frederick
III also promised the creation of an observatory in Berlin,
which was then inaugurated on January 19, 1711.
Gottfried Kirch was awarded the important appointment
of Kalenderpatent eight years after his marriage to Winkelmann, his second wife. Despite the difference in age (Winkelmann was the younger by 30 years), their shared passion
for astronomy nurtured family activity in this ﬁeld. It was
common at the time for women trained in the sciences to
marry a scientist in order to continue her own work. After

the wedding, Gottfried directed Winkelmann-Kirch's studies much as he had done for his three sisters. Between 1700
and 1710, the year of Gottfried's death, their household,
including apprentices, domestic help, friends, and eventually
children, held the monopoly on Prussian calendars.
After Gottfried's death, Winkelmann-Kirch carried on
with her observations in spite of various obstacles. Despite
the fact her husband held the position of Kalenderpatent,
she had always taken care of the preparation of the calendar. However, the Academy of Sciences denied her request
when she asked that she and her son be appointed assistant
astronomers in charge of producing calendars. Despite the
open support of its president, the physicist and philosopher
Gottfried Leibniz, the Academy wished to avoid the precedent
of a woman at a public institution, and rejected her application. Ironically, it was nonetheless necessary to ask her to
continue the same work in an unofﬁcial capacity.
In October 1712 Winkelmann-Kirch was admitted as an
astronomer to the private observatory of Baron Bernhard
Friedrich von Krosigk in Berlin, where she and Gottfried had
worked while the Academy observatory was under construction. Here, she observed daily as "master" astronomer and
trained Christine and Christfried as assistants. She published
planetary and lunar ephemerides under her own name and
continued her work on the preparation of calendars for
the cities of Wrocław (the German Breslau), Nuremberg,
and Dresden, as well as for Hungary. When the Baron died
in 1714, she moved to Danzig to reorganize and use the
observatory of the well-known (but deceased) astronomer
Johannes Hevelius.
q ROYAL COMMAND Frederick III, Prince-elector of Brandenburg,
created the official post of Kalenderpatent with this edict, issued on May
10, 1700. The edict, which served as the founding charter for the Electoral Brandenburg Society of Sciences (soon to be renamed the Royal
Prussian Academy of Sciences), also called for the construction of an
astronomical observatory.

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