Since the start of the Foundation in 1987, Jan Deiman MSc, PhD has been an adviser. Jan studied electrical engineering at Delft University of Technology (TU Delft). In his spare time, he worked as Conservator for the Electrical Engineering group. He graduated on the history of the compensator. After finishing his studies in 1984, Jan became responsible for the collection of scientific physical instruments at the Utrecht University Museum, especially the 300 historical microscopes. He started working as the assistant of J. van Zuylen, former head of the Physical Laboratory of the Bleeker (Nedoptifa) company in Zeist. In 1988, G. L’Estrange Turner asked Jan to start a PhD project at the Imperial College of Science, Technology and Medicine in London. Between 1989 and 1991 Jan researched hundreds of microscopes from the collections of the Science Museum in London and the Royal Microscopical Society in Oxford. The result was his thesis Microscope Optics and J.J. Lister’s Influence on the Development of the Achromatic Objective 1750-1850. His knowledge of microscopes is therefore invaluable for the Foundation. Jan advises on new acquisitions, and writes the descriptions of our microscopes and scientific instruments. He currently lives in Bali.