Originally published in 1922, this book was written to provide 'the modern seaman' with a practical guide to the causes of tidal phenomena. The text explains the correct methods of using tidal information, introduces improved methods of giving such information by means of harmonic constants and explains how, from these constants, the height of the tide may be calculated accurately. Appendices and illustrative figures are included. This book will be of value to anyone with an interest in tides and the history of science.