Mathieu bought the Delin company, with which he had been chief engineer, after it closed in 1902.
In the same factory he built Mathieu automobiles and briefly Automoteurs motorcycles. The company moved to Zaventem near Brussels in 1903, and merged with the Belgica automotive firm in 1906.
Photographers text for the image above reads,
Surprising indeed!
Wikipedia NL, A-Z der Belgische Motoren