With a Complete System of Descriptive Mineralogy. 8vo, cloth, with many illustrations 2 50 *CRAIG, B. F.--Weights and Measures.* An account of the Decimal System, with Tables of Conversion for Commercial and Scientific Uses. Square 32mo, limp cloth 50 *CRAIG, Prof. THOS.--Elements of the Mathematical Theory of Fluid Motion.* 16mo, cloth 1 25 *CRAIGHILL, WM. P.--The Army Officer's Companion.* Principally designed for Staff Officers in the Field. Partly translated from the French of M. de Rouvre, Lieut.-Col. of the French Staff Corps, with additions from Standard American, French, and English authorities. 18mo, full roan 1 50 *CULLUM, Col. GEORGE W.--Military Bridges.* Systems of Military Bridges in use by the U. S. Army; those adopted by the Great European Powers; and such as are employed in British India. With Directions for the Preservation, Destruction, and Re-establishment of Bridges. With 7 folding plates. 8vo, cloth 3 50 *DAVIS, C. B., and RAE, F. B.--Hand-Book of Electrical Diagrams and Connections.* Illustrated with 32 full-page illustrations. Second edition. Oblong 8vo, cloth extra 2 00 *DIEDRICH, JOHN.--The Theory of Strains.* A Compendium for the Calculation and Construction of Bridges, Roofs, and Cranes. Illustrated by numerous plates and diagrams. 8vo, cloth 5 00 *DIXON, D. B.--The Machinist's and Steam-Engineer's Practical Calculator.* A Compilation of Useful Rules, and Problems Arithmetically Solved, together with General Information applicable to Shop-Tools, Mill-Gearing, Pulleys and Shafts, Steam-Boilers and Engines. Embracing Valuable Tables, and Instruction in Screw-cutting, Valve and Link Motion, etc. 16mo, full morocco, pocket form 2 00 *DODD, GEO.--Dictionary of Manufactures, Mining, Machinery, and the Industrial Arts.* 12mo, cloth 1 50 *DOUGLASS, Prof. S. H., and PRESCOTT, Prof. A. B.--Qualitative Chemical Analysis.* A Guide in the Practical Study of Chemistry, and in the Work of Analysis. Fourth edition. 8vo, cloth 3 50 *DUANE, Gen. J. C.--Manual for Engineering Troops.* Consisting of--Part I. Ponton Drill; II. Practical Operations of a Siege; III. School of the Sap; IV. Military Mining; V. Construction of Batteries. With 16 plates and numerous wood-cut illustrations. 12mo, half morocco 1 50 *DUBOIS, A. J.--The New Method of Graphical Statics.* With 60 illustrations. 8vo, cloth 1 50 *DUFOUR, Gen. G. H.--The Principles of Strategy and Grand Tactics.*