Margrett, Lieut-Cmdr A.D.Hydrographic Surveying for Development and Conservancy London Kelvin and Hughes Marine Card Cover Very Good/Good 27cm An explanation on the process of hydrographic survey work with an introduction by Vice-Admiral Day (Hydrographer of the Navy). The book has numerous tables, charts & diagrams with pocket at rear holding a folded map. The book has card covers but may have also had a paper dj as what appears to be the inside flap strip is in the pocket also. K&H publication M274. Lt-Cmdr Margrett retired in 1967.