Chemicals and radioactive materials and human development / Rajiv K. Sinha, Rohit Sinha, Shanu Sinha

American youths to-day are given, if of a mechanical turn of mind, to amateur telegraphy or telephony, but seldom, if ever, have to make any part of the system constructed. In Edison's boyish days it was quite different, and telegraphic supplies were hard to obtain. But he and his "chum" had a line between their homes, built of common stove-pipe wire. The insulators were bottles set on nails driven into trees and short poles.