The company Chasselon is from the precision instruments workshops Brunner Frères. The Brunner house was created in the 1830s by his father, Jean Brunner, and later renamed "Brunner Frères" from 1862 by his two sons Emile (1834-1895) and Léon (1840-1894). As early as 1889, the two brothers, eager to retire, solicited Chasselon, whose father had worked in their studio, to continue the manufacturing of instruments for surveying and surveying. After the death of Léon and then Emile, Chasselon officially took over the company in 1895 and moved to number 20 rue Ducouëdic in Paris. In 1940, Chasselon moved to the Amédée Picard street in Cachan (Seine) and continued to build geodesy and topography instruments until recently. It is precisely these topography instruments that have made the Chasselon house famous, but a number of apparatus related to the measurement of magnetism, such as magnetic theodolites or inclination compasses, are also known from these workshops.