 In that year Thorbecke appointed him as inspector of secondary education for the southern part of the country, in which capacity he had much influence on Thorbecke's newly introduced schooling system, insisting, for example, on specialized classrooms for physicis and chemistry.In 1873 he accepted the chair of the physics department at the Polytechnic School in Delft, which would turn into the Delft University of Technology.In 1875, he published a three-volume "Leerboek der natuurkunde" (Textbook of Physics) in which no higher math was used and which saw many editions.