of the female or lower dies, such as are used for drop forgings, hot and cold machine forging, swedging and the press working of metals. The process of force-making relates to the engraving or raising of the male or upper dies used in producing the lower dies for the press-forming and machine-forging of duplicate parts of metal. The book contains eleven chapters, and the information contained in these chapters is just what will prove most valuable to the forgedmetal worker. 304 detailed illustrations. 341 pages, cloth. Price, $3.00

DICTIONARIES

Aviation Terms-English-French; French-English.

A complete glossary of practically all terms used in aviation, having lists in both French and English with equivalents in either language. A very valuable book compiled by Lieuts. Victor W. Pagé and Faul Montariol. Price, $1.00

Standard Electrical Dictionary.

BY PROF. T. O'CONOR SLOANE. Just issued an entirely new edition brought up to date and greatly enlarged-as a reference book this work is beyond comparison as it contains over 700 pages, nearly 500 illustrations, and definitions of about 6,000 distinct words, terms and phrases. The definitions are terse and concise and includes every term used in electrical science.

In its arrangement and typography the book is very convenient. The word or term defined is printed in black faced type which readily catches the eye, while the body of the page is in smaller but distinct type. The definitions are well worded, and so as to be understood by the non-technical reader. The general plan is to give an exact, concise definition, and then amplify and explain in a more popular way. Synonyms are also given, and references to other words and phrases are made. This work is absolutely indispensable to all in any way interested in electrical science, from the higher electrical expert to the everyday electrical workman. In fact, it should be in the possession of all who desire to keep abreast with the progress of this branch of science. 1920 enlarged edition. Nearly 800 pages and nearly 400 illustrations. Price, $5.00

DRAWING-SKETCHING PAPER

Linear Perspective Self-Taught.

By HERMAN T. C. KRAUS. This work gives the theory and practice of linear perspective, as used in architectural, engineering and mechanical drawings. The arrangement of the book is good; the plate is on the left-hand, while the descriptive text follows on the opposite page, so as to be readily referred to. A self-explanatory linear perspective chart is included in the second revised edition. Cloth. Price, $3.00

1

Self-Taught Mechanical Drawing and Elementary Machine Design.

By F. L. SYLVESTER, M.E., Draftsman, with additions by Erik Oberg, associate editor of "Machinery." A practical elementary treatise on Mechanical Drawing and Machine Design, comprising the first principles of geometric and mechanical drawing, workshop mathematics, mechanics, strength of materials and the calculation and design of machine details, compiled for the use of practical mechanics and young draftsmen. 330 pages, 215 engravings, cloth. Price, $2.50

A New Sketching Paper.

A new specially ruled paper to enable you to make sketches or drawings in isometric perspective without any figuring or fussing. It is being used for shop details as well as for assembly drawings, as it makes one sketch do the work of three, and no workman can help seeing just what is wanted. Pads of 40 sheets, 6 x 9 inches, Price, 25c.; 9 x 12 inches, Price, 50c.; 12 x 18 inches, Price, $1.00.

Practical Perspective.

By RICHARDS and COLVIN. Shows just how to make all kinds of mechanical drawings in the only practical perspective isometric. Makes everything plain so that any mechanic can understand a sketch or drawing in this way. Saves time in the drawing room and mistakes in the shops. tical examples of various classes of work. Limp cloth.

ELECTRICITY

Arithmetic of Electricity.

Contains prac Third edition. Price, 75 cents

By PROF. T. O'CONOR SLOANE. A practical treatise on elec trical calculations of all kinds reduced to a series of rules, all of the simplest forms, and involving only ordinary arith metic; each rule illustrated by one or more practical problems with detailed solution of each one. This book is classed among the most useful works published on the science of electricity, covering as it does the mathematics of electricity in a manner that will attract the attention of those who are not familiar with algebraical formulas. 200 pages. 1920 Revised and Enlarged edition. Price, $1.50

Dynamo Building for Amateurs, or How to Construct a Fifty Watt Dynamo.

This

By ARTHUR J. WEED. A practical treatise showing in detail the construction of a small dynamo or motor, the entire machine work of which can be done on a small foot lathe. Dimensioned working drawings are given for each piece of machine work, and each operation is clearly described. machine, when used as a dynamo, has an output of fifty watts; when used as a motor it will drive a small drill press or lathe. It can be used to drive a sewing machine on any and all ordinary work. The book is illustrated with more than sixty original engravings showing the actual construction of the different parts. Price, Cloth, $1.00

By M. B. SLEEPER. A complete treatise for the practical worker in installing, operating and testing bell circuits, burglar alarms, thermostats and other apparatus used with electric bells. Both the electrician and the experimenter will find in this book new material which is essential in their work. Tools, bells, batteries, unusual circuits, burglar alarms, annunciators, systems, thermostats, circuit breakers, time alarms, and other apparatus used in bell circuits are described from the standpoints of their application, construction, and repair. The detailed instructions for building the apparatus will appeal to the experimenter particularly. The practical worker will find the chapters on Wiring Calculation of Wire Sizes and Magnet Windings, Upkeep of Systems and the Location of Faults of the greatest value in their work. 124 pages. Fully illustrated. Price, 75 cents.

Commutator Construction

By WM. BAXTER, JR. The business end of dynamo or motor of the direct current type is the commutator. This book goes into the designing, building and maintenance of commutators, shows how to locate troubles and how to remedy them; everyone who fusses with dynamos needs this. Fourth edition. Price, 35 cents.

Dynamos and Electric Motors and All About Them.

In

By EDWARD TREVERT. This volume gives practical directions for building a two H. P. Dynamo of the Edison type capable of lighting about fifty mazda lamps of the 20 watt size. addition, it gives directions for building two small electric motors suitable for running sewing machines. The concluding chapter describes the construction of a simple bichromate battery adapted for running electric motors. 96 pages. Fully illustrated with detail drawings. Cloth. Price, $1.00.

Construction of a Transatlantic Wireless Receiving Set.

By L. G. PACENT and T. S. CURTIS. A work for the Radio student who desires to construct and operate apparatus that will permit of the reception of messages from the large stations in Europe with an aerial of amateur proportions. 36 pages. 23 illustrations, cloth. Price, 35 cents.

Electric Toy Making, Dynamo Building and Electric Motor Construction.

This work treats of the making at home of electrical toys, electrical apparatus, motors, dynamos and instruments in general and is designed to bring within the reach of young and old the manufacture of genuine and useful electrical appliances. 210 pages, cloth. Fully illustrated. Twentieth edition, enlarged. Price, $1.50

Experimental High Frequency Apparatus, How to Make and Use It.

By THOMAS STANLEY CURTIS. 69 pages, illustrated.

Price, 50 cents.

By PROF. T. O'CONOR SLOANE. This work has just been revised and much enlarged. It is intended for the practical electrician who has to make things go. The entire field of electricity is covered within its pages. It is a work of the most modern practice, written in a clear, comprehensive manner, and covers the subject thoroughly, beginning at the A B C of the subject, and gradually takes you to the more advanced branches of the science. It teaches you just what you should know about electricity. A practical work for the practical man. Contains forty-eight chapters.

The publishers consider themselves fortunate in having secured the services of such a well and favorably known writer as Prof. Sloane, who has with the greatest care completed a master work in concise form on this all important subject. 600 engravings, 840 pages, handsomely bound in cloth. 1920 Edition. Price, $4.00

Electricity Simplified.

By PROF. T. O'CONOR SLOANE. The object of 'Electricity Simplified" is to make the subject as plain as possible and to show what the modern conception of electricity is; to show how two plates of different metals immersed in acid can send a message around the globe; to explain how a bundle of copper wire rotated by a steam engine can be the agent in lighting our streets, to tell what the volt, ohm and ampere are, and what high and low tension mean; and to answer the questions that perpetually arise in the mind in this age of electricity. 172 pages. Illustrated. Thirteenth edition. Cloth. Price, $1.50 Electric Wiring, Diagrams and Switchboards. By NEWTON HARRISON, with additions by THOMAS POPPE. This is the only complete work issued showing and telling you what you should know about direct and alternating current wiring. The work is free from advanced technicalities and mathematics, arithmetic being used throughout. It is in every respect a handy, well-written, instructive, comprehen. sive volume on wiring for the wireman, foreman, contractor or electrician. Third revised edition. 303 pages, 130 illustrations. Cloth. Price, $2.50

House Wiring.

By THOMAS W. FOPPE. Describing and illustrating up-to-date methods of installing electric light wiring. Contains just the information needed for successful wiring of a building. Fully illustrated with diagrams and plans. It solves all wiring problems and contains nothing that conflicts with the rulings of the National Board of Fire Underwriters. Third edition revised and enlarged. 125 pages, fully illustrated, flexible cloth. Price, 75 cents

High Frequency Apparatus, Its Construction and Practical Application.

By THOMAS STANLEY CURTIS. The most comprehensive and thorough work on this interesting subject ever produced. The book is essentially practical in its treatment and it constitutes an accurate record of the researches of its author over a period of several years, during which time dozens of coils were built and experimented with. New revised and enlarged 1920 edition. 275 pages. Price, $3.00

How to Become a Successful Electrician.

By FROF. T. O'CONOR SLOANE. An interesting book from cover to cover. Telling in simplest language the surest and easiest way to become a successful electrician. The studies to be followed, methods of work, field of operation and the requirements of the successful electrician are pointed out and fully explained. 202 pages. Illustrated. Eighteenth revised edition. Cloth. Price, $1.50

Standard Electrical Dictionary.

BY PROF. T. O'CONOR SLOANE. Just issued an entirely new edition brought up to date and greatly enlarged-as a reference book this work is beyond comparison as it contains over 700 pages, nearly 500 illustrations, and definitions of about 6,000 distinct words, terms and phrases. The definitions are terse and concise and includes every term used in electrical science.

In its arrangement and typography the book is very convenient. The word or term defined is printed in black faced type which readily catches the eye, while the body of the page is in smaller but distinct type. The definitions are well worded, and so as to be understood by the non-technical reader. The general plan is to give an exact, concise defini tion, and then amplify and explain in a more popular way. Synonyms are also given, and references to other words and phrases are made. This work is absolutely indispensable to all in any way interested in electrical science, from the higher electrical expert to the everyday electrical workman. In fact, it should be in the possession of all who desire to keep abreast with the progress of this branch of science. 1920 enlarged edition. Nearly 800 pages. 400 illustrations. Price, $5.00

Storage Batteries Simplified. By VICTOR W. PAGE. M.S.A.E. This is the most thorough and authoritative treatise ever published on this subject. It is written in easily understandable, non-technical language so that any one may grasp the basic principles of storage battery action as well as their practical industrial applications. All electric and gasoline automobiles use storage batteries. Every automobile repairman, dealer or salesman should have a good knowledge of maintenance and repair of these important elements of the motor car mechanism. This book not only tells how to charge, care for and rebuild storage batteries but also outlines all the industrial uses. Learn how they run street cars, locomotives and factory trucks. Get an understanding of the important functions they per form in submarine boats, isolated lighting plants, railway switch and signal systems, marine applications, etc. This book tells how they are used in central station standby service, for starting automobile motors and in ignition systems. Every practical use of the modern storage battery is outlined in this treatise. 208 pages, fully illustrated. Price, $2.00

Wiring a House.

By HERBERT PRATT. Shows a house already built; tells just how to start about wiring it; where to begin; what wire to use; how to run it according to insurance rules; in fact, just the information you need. Directions apply equally to a shop. Fourth edition. Price, 35 cents