Jan Blanken, by J.A. Daiwaille, c. 1825. Hydraulic engineer Jan Blanken (1755-1838) played a key roll in the development of the Dutch water authority after 1800. Despite the political turmoil of those years, this was a period in which major projects were initiated. Under a succession of Dutch governments, Blanken supplied the country with docks, harbours, canals and fortifications. One of his best-known works is the North Holland canal, opened in 1824. In the painting in the background is the entrance to the canal, the Willem sluice at Amsterdam, named after the man who commissioned the work, King William I. Here Blanken is portrayed in his official uniform. Like Goudriaan, he was appointed inspector general of the water authority in 1808. Blanken supported the wearing of uniforms: the corps of engineers was organised along military lines.