sentences:  Together with Gilles Holst, director of Philips Research Laboratories ("Philips Natuurkundig Laboratorium"), he was the driving force behind establishing the Dutch Physical Society ("Nederlands Natuurkundig Vereniging", NNV) in 1921.From 1939 until November 1940 he was Chairman of this Society.From 1918 until 1922 Ornstein was Chairman of the Dutch Zionist Society ("Nederlandse Zionistische Vereniging").