John Hopkinson (1849–98) was a British electrical engineer who invented the three-wire system for the distribution of electricity. Originally published in 1901, this book forms the first in two volumes of Hopkinson's papers, focusing mainly on technical subjects. The text also incorporates editorial notes, numerous illustrative figures and a memoir of Hopkinson's life. Material of a more purely scientific character can be found in the second volume. This book will be of value to anyone with an interest in Hopkinson, engineering and the history of science.