The historical collection of survey instruments was moved to the tower room at Kanaalweg 4 last summer. This means that the items have returned to where surveying once began. From 1895 onwards the building was the cradle of geodesy in the Netherlands and remained in use as such until 1975. Four volunteers have amassed a collection of spirit levels, theodolites and other instruments here. On 27 August, they opened the doors to the tower room for visitors.