NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
The history of Seafaring.
From: George Huxtable
Date: 2007 Dec 7, 18:30 -0000
From: George Huxtable
Date: 2007 Dec 7, 18:30 -0000
It's the time of year when some navigators hint to their wives what they might like as a Christmas present. And right on cue, a new book has appeared to tempt them. This is "The History of Seafaring", by Donald S Johnson and Juha Nurminen, ISBN9781844860401. Cover price in the UK from Conway Books is �40, but my copy came from Amazon.uk at �20 post paid. Here's my summary of what you get. First thing you notice is its immense size, nearly 14 inches by 10 inches, 374 pages of thick paper, weighing over 6 pounds. It classes as a "coffee-table" book, simply because it's too big to fit comfortably on your knee in an armchair. It's beautifully bound and printed, on high-quality paper, to bring out the best in its many pictures. And those pictures are the next thing you notice. They are indeed superb! Selected for their visual impact, many spreading wall-to-wall across those wide double-pages, they really make up a wonderful picture-book. That spread allows the most to be got out of its many ancient maps and charts, oil paintings, and some beautiful modern pictures too, of the sea and its ships. And those pictures are reasonably well captioned. What's more, in general, they are not the same old illustrations that get rehashed from one text to another; most of them are new, to me at any rate. So, if you want a magnificent artwork about the sea and ships, this is for you. From that viewpoint, I have no reservations about this book. But the publishers, on the cover, claim much more. They claim that it "pieces together the advances in astronomy, navigation, shipbuilding, seamanship, and cartography ..." Note that astronomy and navigation come first on that list, and as those topics will interest Navlist readers particularly, let's assess the book on that basis. And on that basis, it fails, in my view, and fails badly. I think I can see some reasons why. At the start, there's a page that's largely given-over to telling us about the team that put the book together. As well as the two authors named above, there are two "other authors". There are 5 "editors", of various sorts. There's an "Executive Committee" with 5 names. There are 5 others, designers, photographers, translators. So this is a book that's been written by a committee. And it shows. How it shows! The book has several different strands. There's a text-strand, presumably the work of Johnson, which is hard to follow through the book, as it gets broken into, sometimes for several pages at a time, by those pictures, which are usually quite irrelevant to the text they interrupt. Next there are what's described as "info boxes", also having little connection with the main text-strand, which appear to have been written by quite a different author or authors, in that there's much duplication of what's already been written. These "info boxes" can go on for 2 or 3 pages, often being hard to distinguish from the text they break into. Frequently, text gets superimposed on the background of a picture, spoiling that picture and rendering the text unreadable, to the detriment of both. There is no cross-referencing, not anywhere. The "info boxes" don't refer to the main text, or to the picture. The text-stream doesn't mention the "info boxes", or the pictures. The picture captions don't refer to the main text or the "info boxes". It's as if these strands had been compiled quite separately, perhaps in different continents, so that each creator was quite unaware of the context in which his own product would appear. Which makes the whole thing completely disjointed. And, to make matters much worse, there is NO INDEX of topics! Why ever not, I ask? There's an index of Names, only, for what that's worth. But let's, as I said. look at the astronomy, and the navigation. Perhaps, in this sort of work, you wouldn't expect to see much about its mathematical basis, and indeed, you don't. Not a single equation, trig expression, mathematical symbol: nothing. But wouldn't you expect, at least, a simple diagram showing how you can get latitude from an altitude of Polaris or midday Sun? Not even that. Many of the simpler concepts of astronavigation have been misunderstood. I will give page numbers in brackets here, in the absence of an index. (150) "Galileo designed an accessory for the telescope that enabled distances to be measured between Jupiter and its moons, thereby determining longitude at sea". Jupiter's moons provided time by their disappearance into shadow, not by measuring their distance from the planet. (151) With Zacuto's Sun declination tables "navigators could determine latitude from the Sun at any time of the day". How? (167) The backstaff description would put it upside-down. The nocturnal is described as correcting for the "parallax" of Polaris. (177) The direction of a line trailed astern would provide "course over the ground". The effects of ocean currents on navigation could be "estimated by their influence on the height and shape of the ocean waves. Not all navigators possessed this skill ..." (194) Descibing the nocturnal. "An almanac provided the orientation at midnight for every night of the year". No almanac was necessary. A nocturnal has its own date-scale, which you set. (203) Labelling for spring tides diagram is wrong. (213) "Robert Hooke invented a method of bringing the object and the horizon together into the field of view by using three mirrors". No, just one mirror. (214) "Local time would be established by observing the altitude of the Sun at noon". No, well away from noon. "Gemma's method ... remained only a theoretical solution for the next 250 years until a portable clock could be constructed that would be sufficiently accurate when taken to sea. Only then could longitude be determined and the art of navigation finally become a science". Thus are lunar distances dismissed. Presumably, he has been reading Sobel. (221) "By not considering the height of the eye above the water, it neglected the effect of parallax". Here. dip and parallax are confused. (292) "The advantage of using the Jovian moons, instead of the Earth's own Moon, was their high frequency of occurrence". No, it was because they provided an almost-instant moment in time, as they extinguished, without the need for precise measurement. "Galileo put forward his idea of using the moons of Jupiter to determine longitude, and supplied tables that could accurately predict their position". No, there were large errors in any such predictions, ranging over a 15 minute error in time, or more. He refers to Maskelyne's voyage in 1769 to observe the transit of Venus, but that was to the 1761 transit. (294), referring to Harrison's clocks, "A pair of counter-balancing springs made the clock independent of gravity; any change in motion of one spring was balanced by the other spring". It did indeed have pairs of springs, but that misses the point, which was that it had two counter-rotating balance wheels, and THEY made it independent of the ship's motion. (339) About the binnacle- "Large iron balls placed on either side of the compass, a system developed later, took care of compass errors caused by non-ferromagnetic influences, such as electrical currents, on the vessel". Not at all, those are quadrantal correctors, there to correct for induced magnetisation in the iron of the vessel caused by the Earth's magnetic field. (344) Says Ross, in 1839, "sailed to within 200 miles of the geographic South Pole before a solid barrier of ice stopped him". Nonsense. (345) Says that Baffin in 1615 was "the first person to use lunar observations at sea to determine longitude". These were done in the ice, hardly at sea, and if Baffin had worked his arithmetic correctly those observations would have put him some thousands of miles EAST of Greenwich; not west of Greenwich as he was! (335) Confuses the Decca navigation chain with Radar! These are some basic errors in those aspects of the subject that I know a bit about. There are several more, that I haven't listed because they would call for somewhat more explanation. It makes me suspect that errors may similarly abound in those topics about which I am unfamiliar. There is an awful lot in that category, about early voyaging and mapping, which may well be of great value, but which I don't know enough about to assess. ===================== Finally, there are no references to back up any of the statements that are made, anywhere. Not a single citation or footnote, in the whole book. There is, however, an extensive list, headed "Literature", at the back. It lists something like 300 works, some vital to the subject, others, in my view, worthless. As I've said, nothing in the text refers to those items. One wonders what that immense list is there for. Do the authors claim to have read all those, in producing this book? Do they recommend that readers should, somehow, look them all up? Or is it simply a list that has been put there to impress? ======================= My summing-up, then is as follows- As a picture-gallery, it is superb. As a work about navigational astronomy, it's suspect, misleading, and erroneous. And as a work of reference and scholarship- forget it! But you may like to invest in it just the same. I don't think my �20 has been mis-spent. George. contact George Huxtable at george@huxtable.u-net.com or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---