Dam structure

Model of a dam structure. Described in the directory of 1779 as "Model of a coffer dam, which the late Councilor of Commerce Polhem declared, at the beginning of the building of the Trollhättan lock works, but which was not accomplished, because of reasons, I'm not aware of. This invention not only looks simple and easy in its context, but advantageous for use in rapid streams, in regard to, that the actual weight of the water will help, to keep the dam at the riverbed.".