Customer Reviews

Compass: A Story of Exploration and Innovation

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Compass takes us back to the day when compasses were not understood, performed poorly, broke, were inconsistent, and often pointed many, many degrees from North.

Yet it was all early mariners had.

Alan tell the story of the development of the compass, particularly the marine compass, from the days of a magnitized piece of steel floating in a bowl of water to today's current marvel, with multiple magnets used to avoid sorts of errors like semicircular deviation and heeling error.

Unfortunately, it is not equal to Dava Sobel's great book on Finding the Longitude. The information seems scarcer, and the writing is not quite as good. It is amazing to learn that almost 1,000 years had to pass before most if not all the errors of a compass were figured out and coorrected, Still highly recommnended

If you navigate, you should have this book to learn the complexity of the compass in your vehicle.

The compass is a fascinating instrument. So simple, but so critical to any traveler.

Gurney starts by telling us about the compass disasters. Thousands of people have died by assuming the compass was a simple device, always true and easy to read. As any Boy Scout can tell you, the compass is almost always wrong. It is predictably wrong, but one needs to know the correction formula.

Given this framework, Gurney organizes his tale upon two themes. First, how does the compass design facilitate easy readings and correct interpretation. Second, did governmental organizations contribute or impede good compass design. In the best light, bureaucracies have to balance the need for 'accuracy' against 'ease of use'. In the worst light, the story is simply one of greed and aristocratic pride. Gurney makes fun of magnetic charlatans and the bureaucrats they fool, but he could have done then settle for a good laugh.

The book spends a chapter or two introducing the early evolution of navigational compasses, but doesn't really get interesting until Gurney's two themes come into focus. They emerge when the British Admiralty takes on the challenge of determining 'north' from an always shifting terrestrial magnetic field. Gurney does a good job bringing his cast of characters to life. There are funny tales about the Royal Society's first 'Museum of Natural History', which required one visit to 'apply' for a entry pass, a second visit to pick up the pass, and a third day trip to actually go inside. Another tales discusses a quack doctor's solution to impotence and fertility: 2 tons of magnets under a bed, a string quartet behind a curtain and a mattress filled with stallion hair. Astronomer Halley comes off looking like Star Trek's Captain Kirk. Lord Kevin's story is not so attractive.

It's an easy read, and at times a bit funny. I learned a lot, but not as much as I could have.

I didn't learn much because the author assumed that I knew more than I did. He mentions terms once and expects that you'll remember them. It's nice to be treated like an intelligent adult, but because I knew next-to-nothing about the subject, I was constantly flipping back to see what words meant. However, if you know a little bit about sailing and navigation, this book is for you. I enjoyed it, even without a background.

No doubt the publisher's aim was to create another "Longitude", but I think "Compass" is even better. Gurney is very good at pen portraits of the many brilliant and eccentric characters who wander into his yarn. The sheer stubbornness with which extremely bright people defended their ideas, long after they were proved wrong or even dangerous, can give one pause. There's no shortage of people like that in our modern society.

What gives the book its particular charm is that the story of the compass is one of advancing technology exposing ever-newer areas of ignorance. Before the first iron-hulled ship was built, who knew that pounding and riveting iron in a dockyard would magnetize the metal? Or that a compass on a metal-hulled ship would give different readings based on the direction the ship was facing?

I learned a LOT about compasses from this book, and I have literally written instruction manuals for teaching about compass use. I am eternally grateful for Gurney's hard work in bringing me such great information mingled with engaging stories that give them vivid context.

But I found the whole story to be overly British-centric. Gurney mentions some evolutions of the compass outside of Britain, and he does a good job at the end, at least mentioning how various Brits discarded valuable clues about compasses they had clearly seen over the second millenium. But I think Gurney is at least 10% as guilty as the bureaucratic villains of his book, shining his spotlight on the British advances, and giving cursory treatment to the non-British advances. I mean this in the best light possible: the subtitle ought to be "the evolution of the British marine compass."

I also learned an incredible amount of history about the British empire at their acme. Gurney helps me understand both what the Brits gave to the world, and how their bureaucracy routinely shot them in the foot.

As a person with a special interest in boat navigation, this book caught my attention. I have other books on the subject, but I could recommend this one without reservation. It combines a history of the mariner's compass as developed in the west (with some comments on Chinese systems) with a great deal of technical information about compasses and compass use. It does all this in an easily-readable form. The information is spaced out with appropriate anecdotes so one is not hit with a lot of technology all at once. Readable and useful.

On opening any book, there can be surprises of both omission, and of commission, and this book was no exception. Finding where you are going has always been a prime use of a magnetic compass, but it is also very useful for finding where you are. A major surprise for me was the nature and complexity of compass errors that historically there have been. A compass is something that is there, and works, isn't it? Well ...... no!

Alan Gurney concentrates, quite rightly in retrospect, in the use of the humble compass at sea. Errors at sea are quite costly, resulting in huge losses, both in terms of human life and the ships that carry the masters of the deck. There can be significant other consequences, sometimes directly financial, at other times a huge environmental impact.

My perspective has always been the use of a compass on dry land, and attempting to find where I am, and how to get to where I want to be, oft-times across rugged terrain. Previous knowledge concerned the variation between true north and magnetic north, and the use of a compass in taking back-bearings.

I learnt a significant amount from this historical account of the improvements in ship-born compasses. What was a surprise to me was how true north and magnetic north varies, both with respect to location and over time. Yes, I knew that the two directions are not the same. However, it was well described how setting a compass to compensate for the variations at, say, Falmouth, will be insufficient when sailing to Newfoundland.

Gurney could have used more diagrams to illustrate the errors that exist with magnetic compasses. The errors themselves with dry-card compasses are neatly explained in an appendix, but diagrams would enhance the description. The means of compensating for the errors can be difficult to follow, and this is shown as some of the real improvements were only slowly recognised (the Flinders bar, and multi-needle compasses being cases in point).

It is only now that I understand what a "binnacle" is - a case or box on the deck of a ship, generally mounted in front of the helmsman, in which navigational instruments are placed for easy and quick reference as well as to protect the delicate instruments. An overall explanation (as above) would have helped me, and no doubt others in their reading, rather than the word being used as if the reader has a working knowledge of the nautical term. However, Gurney explains well the need to have no iron in the construction of this navigational pulpit. He also gives a good guide to the difference between `soft iron' and `hard iron', and how this affects magnetic compasses.

The emphasis in this volume is on the use of the compass up until the start of the 20th century. That was what Gurney set out to do, and in that he has written a good guide. The differences between wooden hulled vessels and their competitors and conquerors, the iron vessels, is well represented. It is obvious with hindsight, but iron vessels presented very different navigational challenges, and in some respects, the hard-won compass lessons had to be re-learnt, because the ground rules had changed.

The liquid compass and the gyroscopic are touched upon as the concluding pages, more to round the history off than as part of the narrative. Both of these developments were brought about by the need for something better. It had never occurred to me before how a submarine could navigate, being in effect an iron cigar. The use of an external magnetic compass viewed by its own periscope system is an ingenious solution, soon surpassed by the gyroscope-based compass.

Gurney gives a perspective both at the start and end of the book by describing two vessels where the electronic compass failed. HMS Vanguard was sailing from England to Cape Town in 1947 when power failed and steering by the stars was the only option. The presence of King George VI on board possibly had a bearing on the subsequent decision of the Royal Navy to always carry magnetic compasses as a fail-safe.

Let's hope that the lessons Gurney brings out are brought home to sailors if such circumstances again prevail.

Peter Morgan (morganp@supanet.com)

"Compass" tells the impressive story of the development of the marine magnetic compass, starting at about 1187 AD and going into modern times. The movement of the ship and the iron used in building the ship, in ship-board weapons, and in items stored on board caused no end of havoc to the magnetic compass' ability to correctly point toward magnetic north. As ship building techniques changed, new ways of correcting for these problems had to be devised. This book described these developments as well as scientific sea-voyages done to discover what the source of these problems was and some information about other methods of marine navigation. Some of this information overlapped a bit with the story told in "Longitude" by Dava Sobel.

There were some black and white illustrations--mainly of the various compass types and maps related to the solving of the compass deviation problem. Since details about the scientific (compass-focused) voyages were included, it would have been nice to have a map showing the route of these voyages. However, I could generally follow the route described without a map.

The author assumed the reader had a certain familiarity with ships and the sea, so he would define those terms only once and not very clearly. The book also focused on the developments in the compass from the perspective of Britain, only briefly mentioning what the rest of the world was doing with compasses.

The book was written in a conversational style and, overall, I found the book enjoyable and well-written. It seemed aimed toward people who use a marine compass--to increase their appreciation for it--but the book will probably also appeal to those who read and enjoyed "Longitude" and to those who like reading about how different technologies have developed.

I enjoyed this and read it in a few evenings. The author creates some suspense with the story of the development of the compass and how various forms of (compass) deviation were identified and addressed. He works in a few stories of voyages of exploration and many characters (mostly English) whom he makes engaging and colorful. I would have liked to see faces of some of them, but there are only graphics of compasses and maps -- which I was happy to see. His writing style is conversational, a little droll. A pleasant read, but not one that I look forward to revisiting.