HARPER’S BEGINNING ELECTRICITY
By Don Cameron Shafer
It is an introduction to electricity, written simply to show boys how the wonderful force may be looked upon as a friend, and even a playmate.
HARPER’S GASOLINE ENGINE BOOK
By Alpheus Hyatt Verrill
A simple and practical guide for all those who own, use, or operate gas and gasoline motors. While intended for boys, it will prove of equal value to older readers.
HARPER’S AIRCRAFT BOOK
By Alpheus Hyatt Verrill
The six divisions of the book are: Why the Aeroplane Flies, Model Aeroplanes, Gliders or Non-propelled Aeroplanes, Various Types of Aeroplanes. Hydro-aeroplanes, and Uses of the Aeroplane.
Each Volume Fully Illustrated. Crown 8vo