, professor of medicine in the university of Vienna, was born at Leyden
, professor of medicine in the university of Vienna, was born at Leyden in 1704, and educated under the celebrated Boerhaave. After having received the degree of M. D. at his native place, he settled
at the Hague, where he practised with success for nearly
twenty years. Baron Van Swieten being acquainted with
the extent of his talents, invited him to remove to Vienna,
with the view of uniting with him in the proposed plan of
reform, which he had prevailed on the empress to support,
in the medical faculty of that capital. De Haen accordingly repaired to that city in 1754; and his merits were
found fully equal to the expectations that had been formed
of them. At the express command of Maria Theresa, he
undertook a system of clinical education, in the hospital
which he superintended, as the most advantageous method
of forming good physicians: the result of this duty was the
collection of a great number of valuable observations, which
were published in the successive volumes of the work entitled “Ratio Medendi in Nosocomio Practico,
” Vienna,