Edward H. Tracy, of New York, has invented, and patented this week, an improvement in the above, whicji is designed to obviate the difficulty attending the washing; away of the foundations of breakwaters. The invention consists in constructing the breakwater, dam, or other structure, with two or more longitudinal compartments, which may be subdivided into cells, and having inner compartments provided with a flooring, the outer compartment being open at its lower end, so that in case the filling of the outer compartment escapes in consequence of the washing away of the foundation directly beneath it, the structure will be retained or supported by the inner compartment or compartments while the front compartment is being re-filled, and until sufficient filling has escaped to form a good foundation.