IN the Journal of the Royal Society of Arts of July 15, 1938, there is published the paper read before a meeting of the Society on February 23 by Mr. Oscar Borer, chief engineer of the River Ouse Catchment Board, in which he gave a survey of the reclamation of tidal lands which has been proceeding on both sides of the North Sea. In a brief note on the geological history of this sea, the author shows that, whether it be accounted for by one theory or another, its water holds in suspension a fine sand or silt which was ground to its present state during the glacial period. This silt only settles in quiet protective bays where the flood water can come to rest ; the aim of the work of reclamation is therefore to create those favourable conditions requisite for the extension of the land from the enormous stock of silt provided by Nature. Nature not only provides the material but also constitutes the agency by which the main operations are carried out. Here the engineer exercises his highest function in studying the methods of Nature and in directing them so that they benefit mankind.