=SMALL DYNAMOS AND MOTORS.= How to make and use them. A practical handbook, by F. E. POWELL. Contents of Chapters: 1. General Considerations. 2. Field Magnets. 3. Armatures. 4. Commutators and Other Details. 5. Tables of Windings. 6. How to Build a Small Machine. 7. Useful Data. 8. Testing and Repairing. 76 pages, fully illustrated with detail drawings. =UNIVERSAL TIME CARD MODEL.= By setting to the desired hour at any one place the movable model will show at a glance the actual time of all the other places in the world. Printed in two colors. CROSS SECTION BOOKS 25c. each. =THE HANDY SKETCHING BOOK.= Size 5◊8, scale 8 to 1 in. =THE HANDY SKETCHING PAD.= Size 8◊10, scale 8 to 1 in. =ELECTRICIANS' SKETCHING BOOK.= Size 5◊8, scale 10 to 1 in. =ELECTRICIANS' SKETCHING PAD.= Size 8◊10, scale 10 to 1 in. =PLOTTING PAD.= Size 9◊11, scale 16 to 1 in. * * * * * =ELECTRICAL INSTRUMENTS and TESTING.= How to Use the Voltmeter, Ammeter, Galvanometer, Potentiometer, Ohmmeter, the Wheatstone Bridge, and the Standard Portable Testing Sets. BY NORMAN H. SCHNEIDER. Author of "Care and Handling of Electric Plants," "Induction Coils and Coil Making," "Circuits and Diagrams," etc., etc. The aim of the author has been to produce a complete and practical work on this important subject. First describing the various forms of Electrical Testing and Measuring Instruments and their construction. Secondly, their practical application to everyday work with numerous examples worked out. Thirdly, detailing the many tests of insulation resistance, current and e.m.f. that can be made with a voltmeter. Using only formulas in simple algebra and then explaining them in plain language for the benefit of practical men lacking a knowledge of mathematics. During the past ten years the author has made hundreds of tests, which has made him familiar with the subject from the practical standpoint. He has also obtained valuable information and diagrams from the principal manufacturers of Testing Instruments. The apparatus described is modern and in universal use. Most of the diagrams have been specially drawn for this book. The work is divided into XI. chapters as follows: Introduction; Chapters I. and II, The Galvanometer; III, Rheostats; IV, The Voltmeter; V, The Wheatstone Bridge; VI, Forms of Portable Sets; VII, Current Flow and e.m.f.; VIII, The Potentiometer; IX, Condensers; X, Cable Testing; XI, Testing with Voltmeter. =230 pages, 105 illustrations and diagrams, 12mo., cloth, $1.00.= * * * * * EVERYBODY'S BOOK ON ELECTRICITY. PRACTICAL ELECTRICS. A UNIVERSAL HANDY-BOOK ON EVERYDAY ELECTRICAL MATTERS.