Gate of a wing-gate sluice. Model, 1808. Whatever the water level, the gates of this sluice could be operated by using the water pressure. In 1808 King Louis Napoleon granted engineer Jan Blanken a patent for this type of sluice, known as a Blanken sluice. According to Blanken's colleague Goudriaan, the invention had already been made by someone else. This clash led to an acrimonious conflict between the two inspectors general.