Ebb and Flow: Tides and Life on Our Once and Future Planet.

Janet Arnett is the former campus manager of adult education at Ontario’s Georgian College. She is the author of Antiques and Collectibles: Starting Small, The Grange at Knock, and 673 Ways to Save Money.

The three threads in this work—history, science, and personal journal—are beautifully and seamlessly integrated into the story of tides. Tides shape our world, sometimes with munificence and sometimes with powerful, destructive forces.

The history thread starts in pre-history and moves through the Middle Ages to the Victorian Age and into the present. There is just enough historical detail to provide a framework of continuity to man’s search for knowledge of the tides.

The personal journal thread is a delight to read. Koppel’s own world-wide travels and observations knit the reality of today’s tides into an engaging documentary. Many of his adventures take place on the B.C. Coast, and some of the most interesting observations are on New Brunswick’s Bay of Fundy, giving a strong Canadian presence to accounts set throughout the world, from Hawaii to Norway, and Europe to Australia.

And then there’s the science thread. This is the heavy player, doing the bulk of the work. Although every attempt is made to make tide theory comprehensible to the average reader, in the end science wins and those without a leaning for physics and math will soon be lost in the complexities of the subject. That subject is the micro-, meso-, macro- and mega-tides of the world, including tidal rapids, tidal currents, tidal mud flats, storm surges, whirlpools (“a sea gone mad”), boulder barricades, flowerpot rocks, and other unusual features created by tides. Over time, there have been three main theories promoted to explain tidal action: Newton’s equilibrium theory, the progressive wave, and harmonic analysis theories. A sprinkling of diagrams support the explanations, and there’s generous use of comparisons to familiar objects and actions such as the vibrations set in motion when a guitar string is plucked. Nonetheless, it comes across as heavy slogging for the lay reader. To compound the problem for the struggling non-scientist, there is no index.

Throughout history tides have influenced shipping, fishing, commerce, and military action. Tides have presented both great advantages and great hazards, often resulting in massive loss of life. Tides affect biodiversity. They have potential as a source of electricity, yet may have a role in rapid climate change and global warming.

Overall, this work is a deep look at the science of tides and a thoughtful speculation on how our knowledge of tides may be used in the future. It scores high on research and credibility.