*LOCK, C. G., WIGNER, G. W., and HARLAND, R. H.--Sugar Growing and Refining.* Treatise on the Culture of Sugar-Yielding Plants, and the Manufacture and Refining of Cane, Beet, and other sugars. 8vo, cloth, illustrated 12 00 *LOCKWOOD, THOS. D.--Electricity, Magnetism, and Electro-Telegraphy.* A Practical Guide for Students, Operators, and Inspectors. 8vo, cloth *LORING, A. E.--A Hand-Book on the Electro-Magnetic Telegraph.* Paper boards 0 50 cloth 75 Morocco 1 00 *LUCE, Capt. S. B.--Seamanship.* For the use of the United States Naval Academy. Fourth edition. Crown 8vo, revised and improved, illustrated by 89 full-page copperplate engravings, half roan 7 50 --> Text-Book at the U. S. Naval Academy, Annapolis. ---- *Naval Light Artillery.* By Lieut. W. H. Parker, U. S. N. Third edition, revised by Capt. S. B. Luce, Assistant Instructor of Gunnery and Tactics at the U. S. Naval Academy. 22 plates. 8vo, cloth 3 00 *MacCORD, Prof. C. W.--A Practical Treatise on the Slide-Valve by Eccentrics,* Examining by methods the action of the Eccentric upon the Slide-Valve, and explaining the practical processes of laying out the movements, adapting the valve for its various duties in the steam-engine. Second edition. Illustrated. 4to, cloth 2 50 *McCLELLAN, Gen. GEO. B.--Report of the Army of the Potomac,* Of its operations while under his command. With maps and plans. 8vo, cloth 1 00 Paper 50 *McCULLOCH, Prof. R. S.--Elementary Treatise on the Mechanical Theory of Heat, and its application to Air and Steam Engines.* 8vo, cloth 3 50 *MANUAL OF BOAT EXERCISE.* At the U. S. Naval Academy, designed for the practical instruction of the Senior Class in Naval Tactics. 18mo, flexible cloth 50 *MENDELL, G. H.--Military Surveying.* A Treatise on Military Surveying, Theoretical and Practical, including a description of Surveying Instruments. With 70 wood-cut illustrations. 12mo, cloth 1 50 *MERRILL, Col. WM. E., U. S. A.--Iron Truss Bridges for Railroads.* The method of calculating strains in Trusses, with a careful comparison of the most prominent Trusses, in reference to economy in combination, etc., etc. Illustrated. 4to, cloth 5 00 *MICHAELIS, Capt. O. E.--The Le Boulenge Chronograph.*