Summary: THE deterioration of engineering structures exposed to the action of the sea is at present being investigated by two important research organisations. In Great Britain, a committee of the Institution of Civil Engineers, acting under the Department of Scientific and Industrial Research, was established in 1916 and has issued three interim reports which have already been noticed in NATURE (October 21, 1920, p. 235; December 30, 1922, p. 878; and November 17, 1923, p. 741). In the United States a committee was appointed in 1922 by the National Research Council, following an inquiry by a local committee on a devastating outbreak of shipworm in timber structures in San Francisco Bay in the years following 1914. The report of this American Committee, now published, records a great mass of observations and experiments, ably digested and summarised by Col. Atwood, Mr. A. A. Johnson, and their collaborators. While the general scope of the inquiry is the same in both cases, the American investigators have given less attention than have their British colleagues to the corrosion of metal structures and have devoted themselves more particularly to the problem of protecting timber from the attacks of marine boring animals.