=THE MERCURIAL AIR PUMP.= By PROF. SILVANUS P. THOMPSON, D. Sc. 37 pages, 43 illustrations, large 8vo., paper, 60c.[++] =THERMO-ELECTRIC REACTIONS AND CURRENTS, BETWEEN METALS IN FUSED SALTS.= By THOMAS ANDREWS, F.R.S. 18 pages, with illustrations and tables, 8vo., paper, 40c.[++] =THE APPLICATION OF ELECTRICITY TO RAILWAY WORKING.= By WILLIAM EDWARD LANGDON. Contents of Chapters: 1, On the construction of a telegraph line. 2, Surveying. 3, Construction. 4, Telegraph instruments and batteries. 5, Block signalling. 6, Single line working. 7, Automatic block signalling. 8, Interlocking. 9, Miscellaneous appliances in connection with block signalling. 10, Train lighting. 11, Electric light and power. 12, Intercommunication in trains. 13, Administration. Appendix. Index. 301 pages, 6 full page plates and 143 engravings and diagrams, 8vo., cloth, $5.00. =ELECTRICAL TESTING OF TELEGRAPH CABLES.= By COL. V. HOSKIAER. Third edition. 12mo., cloth, $1.50. =HARD SOLDERING, A MANUAL OF INSTRUCTION IN.= By H. ROWELL, with a chapter on soft soldering and brazing. 12mo., cloth, 75c. * * * * * JUST OUT. 293 pages, 298 illustrations, 8vo. Cloth, $1.00 net. THE MODEL LIBRARY VOL. I. Consisting of the following four American books, with very complete general index. =The Study of Electricity= and Its Laws for Beginners. =How to Install Electric Bells=, Annunciators and Alarms. =Dry Batteries=, How to Make and Use Them. =Electrical Circuits= and Diagrams. Illustrated and explained. * * * * * 25c. BOOKS. =ELECTRICITY.= The study of, and its laws for beginners, comprising the laws of electric current generation and flow, Ohm's law, galvanism, magnetism, induction, principles of dynamos and motors, wiring, with explanations of simple mathematics as applied to electrical calculations. By N. H. SCHNEIDER. With 55 original illustrations and 6 tables. =DRY BATTERIES.= A practical handbook on the designing, filling and finishing of dry batteries, with tables, for automobiles, gas engine, medical and coil work, electric bells, alarms, telephones, experiments and all purposes requiring a first-rate battery. Fully illustrated with 30 original drawings. =ELECTRICAL CIRCUITS AND DIAGRAMS.= Being a selection of original up-to-date and practical diagrams for installing annunciators, alarms, bells, electric gas lighting, telephones, electric power light and wiring circuits, induction coils, gas engine igniters, dynamos and motors, armature windings. By N. H. SCHNEIDER.