By far the most complete and valuable original contribution to the study of explosives which has been made in this country is the work of General Henry L. Abbot, Eng. Corps, U.S.A., which has been published by the War Department, under the tide "Report upon Experiments and Investigations to develop a System of Submarine Mines for defending the Harbors of the United States," being No. 23 of the Professional Papers of the Corps of Eng., U.S.A. In a quarto of 444 pages, fully supplied with illustrations, diagrams and tabulated data. General Abbot gives the results of thirteen years of experimental investigation and mathematical study of the data thus obtained.