HÁJEK von HÁJEK, Tadeáš

H’s father, Simon H., a scholar and naturalist, was the acquaintance of Nicholas Copernicus and he possessed his files. His house "U hájků", next to the Bethlehem Chapel in Prague old town center was considered a place, where Prague intelligence would gather.
H. studied languages, philosophy, mathematics and astronomy in Prague. In 1548 he went to Vienna and listened to lectures on medicine and astronomy. In 1550 he returned to Prague, a year later received his MA and began to teach at university.
In following years he often travelled abroad for the purposes of study, including to Vienna and later Bologna, where he obtained his PhD. Shortly thereafter, he travelled to Milan to attend lectures held by Girolamo Cardano, a recognized physician and mathematician. When he returned to Prague in 1555, he again began lecturing mathematics at the University, while writing an essay entitled De laudibus Geometriae. He soon left the University and began dealing with medicine and botany. In 1562 he arranged the Czech edition of Mattiolis’s Herbarium.
As a surveyor, he between 1556 and 1563 together with his students triangulated the area around Prague and set out on a few journeys within the Czech region in order to obtain coordinates and a basis for making a map of Czech Republic. Since the Emperor declined his further support, he had to stop working on the map. As an army doctor he participated in the campaign against the Turks in Hungary between 1566 and 1570. In 1571 he was ennobled, becoming Proto-Medikus of the Kingdom of Czech Republic and was appointed personal physician to Emperor Maximilian II. and his successor Rudolf II. H. was also concerned with alchemy. As one of the major natural scientists of the Rudolf's court, he enjoyed the full confidence of the emperor. He was responsible for alchemists who came to Prague in order to enter the imperial service. He published a calendar, the so-called Minuce, which in addition to calendar information contained also instructions for farmers and astrological forecasts. H. is also regarded a defender of the Gregorian calendar reform, for which the Emperor Rudolf II also decided in 1584.
The centre of his interest was astronomy. His most important work Diagrammata... contains the calculations of lunar and solar eclipses. In 1572 there was a new star discovered in the Cassiopeia constellation, which was described by H. in his work Dialexis de novae et prius incognitae stelae. H. is probably also the author of a new method of determining the position of stars, as well as measurements of height and time of passage through the meridian. He was also concerned with the calculations of distance, composition and origin of comets. When they were visible he measured their daily position.
In 1576 H. met the Danish astronomer Tycho Brahe at the celebration of the coronation of Rudolf II. Together with Giordano Bruno, Tycho Brahe and Johannes Kepler, H. belongs to a narrow circle of scientists who gathered in Prague in the reign of Rudolf II.