Complete and unabridged. Cells, batteries, coils, motors, telegraph keys and a wireless outfit, with the wiring diagrams and the materials a boy could actually obtain. Joseph Adams wrote practical books for Harper's when electricity was still assembled at home from zinc, wire and jars. It is the counterpart of the theory books: everything here is meant to be built by Saturday. Its 90 original illustrations have been carefully restored and coloured for this edition.