The shocking coils, telegraph instruments, batteries, electromagnets, motors, etc., etc., are so simple in construction that any boy of average ability can make them; in fact, the illustrations have been made directly from apparatus constructed by young boys. The author has been working along this line for several years, and he has been able, _with the help of boys_, to devise a complete line of simple electrical apparatus. =_THE APPARATUS IS SIMPLE because the designs and methods of construction have been worked out practically in the school-room, absolutely no machine-work being required._= =_THE APPARATUS IS PRACTICAL because it has been designed for real use in the experimental study of elementary electricity._= =_THE APPARATUS IS CHEAP because most of the parts can be made of old tin cans and cracker boxes, bolts, screws, wires and wood._= =Address, THOMAS M. ST. JOHN,= =407 West 51st Street,= =New York.= How Two Boys Made Their Own Electrical Apparatus. =CONTENTS:= _Chapter_ I. Cells and Batteries.--II. Battery Fluids and Solutions.--III. Miscellaneous Apparatus and Methods of Construction.--IV. Switches and Cut-Outs.--V. Binding-Posts and Connectors.--VI. Permanent Magnets,--VII. Magnetic Needles and Compasses.--VIII. Yokes and Armatures.--IX. Electro-Magnets.--X. Wire-Winding Apparatus.--XI. Induction Coils and Their Attachments.--XII. Contact Breakers and Current Interrupters.--XIII. Current Detectors and Galvanometers.--XIV. Telegraph Keys and Sounders.--XV. Electric Bells and Buzzers.--XVI. Commutators and Current Reversers.--XVII. Resistance Coils.--XVIII. Apparatus for Static Electricity.--XIX. Electric Motors.--XX. Odds and Ends.--XXI. Tools and Materials. "The author of this book is a teacher and wirier of great ingenuity, and we imagine that the effect of such a book as this falling into juvenile hands must be highly stimulating and beneficial. It is full of explicit details and instructions in regard to a great variety of apparatus, and the materials required are all within the compass of very modest pocket-money. Moreover, it is systematic and entirely without rhetorical frills, so that the student can go right along without being diverted from good helpful work that will lead him to build useful apparatus and make him understand what he is about. The drawings are plain and excellent. We heartily commend the book."--_Electrical Engineer._