Teylers Museum holdings include fossils (some are the first ever discovered of
Archaeopteryx), minerals, scientific instruments, medals, coins, and paintings. The museum's first director,
Martinus van Marum contributed to and used the facilities at Teylers Museum to research static electricity. To study fossils, he purchased fossil material such as the
Mosasaurus. To demonstrate the principles of hydraulics, he commissioned models of mills and cranes. To disseminate natural and cultural knowledge, public experiments were conducted, such as those with van Marum's
large electrostatic generator built in 1784 by John Cuthbertson in Amsterdam (the largest in the world). Lectures were given and scientific literature published. The collection of Teylers Museum holdings include works by
Michelangelo,
Raphael,
Guercino, and
Claude Lorrain. The museum contains graphic work of
Rembrandt and
Adriaen van Ostade. The Painting Galleries show a collection of works from the Dutch Romantic School and the later
Hague and
Amsterdam Schools, including major works by
Barend Cornelis Koekkoek,
Andreas Schelfhout,
Cornelis Springer,
Hendrik Willem Mesdag,
Jan Willem Pieneman,
Anton Mauve,
Jacob Maris,
Jan Hendrik Weissenbruch,
George Hendrik Breitner,
Jozef Israëls, and
Isaac Israëls. In 2007, the works of
John James Audubon were displayed. The original mission of the second society included research, as well as education. After the death of van Marum, Teylers continued to attract scientists of high standing as caretakers. The theoretical physicist and
Nobel Prize winner
Hendrik Lorentz was appointed Curator of Teylers Physics Cabinet in 1910, a position he held until his death in 1928. At the time of his appointment, Lorentz was at the height of his scientific career and was a central figure in the international community of physicists. Under his leadership, the Teylers Museum conducted scientific research in such diverse fields as optics, electromagnetism, radio waves, and atom physics. Lorentz was succeeded by the physicist and musician
Adriaan Fokker. Physicist
Wander Johannes de Haas served as conservator in the 1920s. The museum's entire archives have also survived intact. They include the complete series of accounts for all acquisitions, extensions, salaries and day-to-day purchases since 1778, the complete series of visitors' books since 1789, and the minutes of all meetings of the museum board since 1778. The museum is open six days a week; Tuesdays-Sundays 10:00-17:00. == Heritage site ==