He was unsuccessful in the attempt to vindicate the possession of the district of Merwede, between the mouths of the Maas and the Waal, against Dirk III, Count of Holland, in the Battle of Vlaardingen in 1018.
[1] The imperial award required the restitution of this territory to the bishop and the destruction of a castle which Dirk had built to control the navigation of the Maas; but the expedition under Godfrey of Brabant which undertook to enforce this decision was defeated; and in the subsequent agreement the disputed land remained in Dirk's possession.
His principal achievement of this kind was the completion within a few years of the great romanesque Cathedral of Saint Martin at Utrecht.
He wrote a mathematical treatise on establishing the volume of a sphere, Libellus de ratione inveniendi crassitudinem sphaerae, which he dedicated to Pope Sylvester II, who was himself a noted mathematician.
A music theory discussion, Quemadmodum indubitanter musicae consonantiae judicari possint, seems, according to Hauck, to have been ascribed to him on insufficient grounds.