A collection chapters on the theory, rather than the practice, of pre-modern navigation. I suspect it will be of greatest interest to readers familiar with sailboats as it spends a lot of pages on hull design, the use of sails, and, how subtle changes in currents and waves indicate the presence of land beyond the horizon. A nice book for those of us who prefer finding our way through the world with the GPS shut off. ( )

This isn't a how-to manual on finding your way out of the bush (or across the sea) when the batteries in your GPS device run out; it's a serious attempt to produce a scientific and historical account of the tools and techniques that humans used for finding their way about the planet before the age of electronics, looking critically at how well they work, how far they are applicable in different places and under different conditions, and how far the science underlying them may have got mixed up with tradition. From time to time, as well as referring to previous research, Huth describes experiments he did himself to test the things he is writing about.

The book ends with a short story about a navigator from the Gilbert Islands that seems to be constructed as a kind of thought experiment putting together knowledge assembled in the rest of the book, but is also entertaining enough to stand in its own right.

Huth covers a lot of different topics and is pretty uncompromising when it comes to the scientific rigour of his descriptions, so there will be places where readers without a background in physics or navigation might feel they are getting left behind by the pace, but most of it should be fairly accessible to anyone.

I found that there wasn't a huge amount in the subjects covered that was really new to me (except for the material about Pacific Island navigation, where I haven't really read much since Kon-Tiki), but it was always very interesting to see the material in the light of Huth's analysis. One nice example of this is his study of the piece of American folk-wisdom "moss grows on the north side of trees". The experimental evidence shows that this is essentially useless for navigation - there are so many things that can make moss grow in different places, and there is also lichen that looks very like moss to the non-botanist, but doesn't have the same fondness for damp conditions that might make it grow preferentially on the shady side of trees. Outdoor manuals have been warning hikers against relying on it since at least the late 19th century. But there is a quite separate tradition of discourse in the humanities that associates this technique with the Underground Railroad and in particular credits Harriet Tubman with moss-based navigational skills, in defiance (as far as Huth is concerned) of all the facts.

Another example he highlights where scientific and non-scientific accounts diverge is Al Biruni's experiment to estimate the diameter of the earth by measuring the dip-angle of the horizon from the top of a mountain in Pakistan, around the year 1000 AD. He's frequently credited with getting a figure that is within a few km of the modern one, but Huth points out that such an accurate result - if indeed it is the figure he really got - could only have been obtained by accident, as the need to correct for refraction due to thermal differences in air density was not known in Al Biruni's time, and this error should have put his result out by about 20%.

Huth doesn't seem to have a political axe to grind on either Arab science or African-American history - his point is simply that when we cite scientific facts, we should do so with a scientific understanding of what we're talking about. Or at least check the scientific literature as well as the history.

Not necessarily a useful book in a practical sense, but definitely a very interesting one, and one from which people with a lot of different fields of interest will be able to pull something that challenges their preconceptions. ( )

Although this book wasn't what I expected to be, for the most part I found it interesting, if a little more detailed in places than I would have liked. At the beginning, Huth, a Harvard physics professor, talks about how technology has lessened our abilities to navigate by the stars, predict the weather, use compasses, etc. I thought this book would help me learn techniques for finding my way. Huth notes he taught a course on this topic, and gave his students some practical assignments, so I thought, or hoped, some of them would find their way into the book.

Instead, Huth has written a comprehensive book, heavy on the physics (not surprisingly) but with helpful illustrations, that covers everything from ancient navigation techniques to how people get lost to maps and compasses; the stars, the sun, and the moon; latitude and longitude; weather and storms; waves, tides, and currents; and the construction of hulls and sails. As can be seen, the book focuses more on ocean navigation than on finding one's way on land. Throughout, Huth stresses how vital sustained observation and practice are, and how navigators need to cross-check information obtained in different ways, especially if one reading or interpretation is unexpected.

Some of the most interesting parts of the book for me were the discussions of ancient feats of navigation, especially by the Norse and by Pacific Islanders, and also later, not always successful, feats of Arctic exploration. It is a remarkable testament to the human ability to observe, interpret, and remember patterns of stars, waves, weather, etc., that can be put to practical use. Needless to say, this information and practice are also important in military training.

I didn't attempt to study most of the topics in the book, but instead tried to get a flavor of what Huth was talking about; this was especially true for the sections about navigating by the stars, observing the relative height of the sun at noon, and understanding cloud patterns and what they reveal about weather. By the time I got to the last chapters about boat construction, I was skimming. On the other hand, I found the very limited practical information interesting, such as how big an angle of the sky your hand covers when you hold a fist out at the end of an outstretched arm. Of course, I am unlikely to use this information, but if someone were to condense a handbook of do-it-yourself techniques from the mass of physical information in this book, I would buy it.