CONTENTS.

CHAPTER. PAGE.

I. Cells and Batteries, 5

II. Battery Fluids and Solutions, 15

III. Miscellaneous Apparatus and Methods of Construction, 20

IV. Switches and Cut-Outs, 28

V. Binding-Posts and Connectors, 32

VI. Permanent Magnets, 37

VII. Magnetic Needles and Compasses, 40

VIII. Yokes and Armatures, 45

IX. Electro-Magnets, 51

X. Wire-Winding Apparatus, 60

XI. Induction Coils and Their Attachments, 64

XII. Contact Breakers and Current Interrupters, 75

XIII. Current Detectors and Galvanometers, 78

XIV. Telegraph Keys and Sounders, 92

XV. Electric Bells and Buzzers, 104

XVI. Commutators and Current Reversers, 110

XVII. Resistance Coils, 114

XVIII. Apparatus for Static Electricity, 117

XIX. Electric Motors, 122

XX. Odds and Ends, 133

XXI. Tools and Materials, 137-141

A WORD TO BOYS.

The author is well aware that the average boy has but few tools, and he
has kept this fact constantly in mind. It is a very easy matter for a
skilled mechanic to make, with proper tools, very fine-looking pieces of
apparatus. It is not easy to make good apparatus with few tools and a
limited amount of skill, unless you follow simple methods.

By following the methods given, any boy of average ability can make the
apparatus herein described.

Most of the illustrations have been made directly from apparatus
constructed by young boys.

It is impossible to describe the different pieces of apparatus in any
special or logical order. It is taken for granted that you have some
book of simple experiments and explanations to serve as a guide for the
order, and to give you an idea of just the apparatus needed for the
special experiments.

It would be foolis