Medicine and teaching In 1835 he obtained his medical degree from the
University of Utrecht and spent the following years as a doctor in
Oudewater. From 1841 he taught classes in medicine at the
Athenaeum of
Franeker, and two years later returned to the
University of Utrecht, where he worked until retirement in 1875. At
Utrecht he was a full professor of
pharmacology and
plant physiology (from 1846), and later
zoology (from 1855). In 1856 he was appointed director of the zoological museum.
Microscope . Its actual function and creator has been disputed. Throughout his career he maintained an avid interest in the historical development of the
microscope and in the
manufacture of lenses. He is credited with making design improvements to the microscope, and was the author of a landmark book on microscopy that was translated into several languages, including German (
Das Mikroskop, 1859 by
Friedrich Wilhelm Theile). At Utrecht he established a popular microscopy laboratory for students.
Hydrology and geological cartography In the field of hydrology he conducted extensive scientific
groundwater research in an effort to improve the quality of water for public health. In collaboration with other scientists he formed the first committee for creation of a
geological map of the Netherlands. ==Views and legacy==