Category: Navigation

Birds Discover Longitude

Published on by Jonathan Crowe

Eurasian reed warblers don’t need no stinkin’ marine chronometers. A new study suggests that the migratory birds make use of magnetic declination to determine longitude, “at least under some circumstances under clear skies. Experienced migrants tested during autumn migration in Rybachy, Russia, were exposed to an 8.5° change in declination while all other cues remained unchanged. This corresponds to a virtual magnetic displacement to Scotland if and only if magnetic declination is a part of their map. The adult migrants responded by changing their heading by 151° from WSW to ESE, consistent with compensation for the virtual magnetic displacement.”

Not, it would seem, accurate enough for the species to earn a chunk of the Longitude Prize, and it’s not like John Harrison should have been messing about with birds instead of clocks, but interesting all the same. [GeoLounge]

Earliest Known Astrolabe Confirmed by 3D Imaging

Published on by Jonathan Crowe
University of Warwick

An artifact recovered in 2014 from the wreck of one of Vasco da Gama’s exploring ships, the Esmerelda, which sank in the Indian Ocean 1503, was believed to be an astrolabe, a navigation tool used to measure the inclination of celestial objects, but the 17.5-cm bronze disc appeared to lack any navigational markings. Scanning and 3D imaging the object at the University of Warwick revealed etches separated by five degrees along the edge, confirming that it was, in fact, an astrolabe. It’s dated to between 1495 and 1500, roughly, which makes it the oldest known astrolabe still in existence. BBC News. [Tony Campbell]

A Brief History of Maps

Published on by Jonathan Crowe

Distilling the entire three-thousand-year history of maps and mapmaking into a 2,400-word article seems awfully hubristic, but Clive Thompson’s piece for the July 2017 issue of Smithsonian Magazine gives it a try, tying everything together right from the outset:

Is it possible that today’s global positioning systems and smartphones are affecting our basic ability to navigate? Will technology alter forever how we get around?

Most certainly—because it already has. Three thousand years ago, our ancestors began a long experiment in figuring out how they fit into the world, by inventing a bold new tool: the map.

[Tony Campbell]

The Lost Art of Asking for Directions

Published on by Jonathan Crowe

“If my parents lamented a generation lost to knowing how to read a paper map, I’m wondering if mine will note the loss of one who doesn’t need the people of the places it passes through,” writes Lorraine Sommerfeld in a piece for Postmedia’s Driving that celebrates the advantages of asking locals for directions rather than relying on your car’s navigation system.

Harrison Reassessed

Published on by Jonathan Crowe

Jim Bennett, author of the new book, Navigation: A Very Short Introduction (Oxford University Press), reassesses the history of John Harrison and his marine chronometer solution to the longitude problem, a story that has been popularized by Dava Sobel’s 1995 bestseller, Longitude (reviewed here).

It is difficult to claim without important qualification that Harrison solved the longitude problem in a practical sense. In the broad sweep of the history of navigation, Harrison was not a major contributor.

The Harrison story seems to attract challenge and controversy. The longitude exhibition at the National Maritime Museum in 2014 was an attempt to offer a more balanced account than has been in vogue recently. The Astronomer Royal Nevil Maskelyne, for example, has been maligned without justification. A recent article in The Horological Journal takes a contrary view and offers ‘An Antidote to John Harrison’, and we seem set for another round of disputation. From a historian’s point of view, one of the casualties of the enthusiasm of recent years has been an appreciation of the context of the whole affair, while a degree of partisanship has obscured the legitimate positions of many of the characters involved. There is a much richer and more interesting story to be written than the one-dimensional tale of virtue and villainy.

Gender Differences in Spatial Ability Are a Social Construct

Published on by Jonathan Crowe

A recent psychology paper challenges the notion that men are better than women at directions. When the same test was presented as a measure of spatial ability that women typically did worse at, women did worse than men. But when the same test was presented as a measure of empathy, women did just as well as men. Social conditioning, in other words, may be at play here. Good magazine. [MAPS-L]

How Not to Get Lost

Published on by Jonathan Crowe

I am not one of those people who is always getting themselves lost. In fact the idea of lost is a more or less academic concept to me: I have a rock-solid sense of direction. I suspect that the same is true for most of the map aficionados who read this website. But maybe you are someone who gets lost very easily, or you at least know someone who is. For such people, the New York Times’s Christopher Mele has a set of practical tips to improve your sense of direction, most of which are predicated on grounding yourself, observing your surroundings and relying not so much on the technology. [MAPS-L]

Mapcodes

Published on by Jonathan Crowe

The New Yorker‘s Elements blog has a piece about mapcodes. These are short alphanumeric codes assigned to every location on the planet, with short codes reserved for areas of high population density. It’s meant to be a substitute for latitude and longitude, and aimed at parts of the world where there are no formal addresses (which makes directions somewhat interesting): give someone a mapcode, and you’re giving them a very precise location.

The Peace Tower in Ottawa, for example, has an Ontario mapcode of 09W.YK (mapcodes exist within country and state/provincial contexts).
The main problem, as I see it, is that while the Mapcode Foundation is trying to make mapcodes a standard, it still relies on data tables to produce the code, which is to say that there’s some computational overhead. Whereas something like Universal Transverse Mercator coordinates can be derived from topo maps (which have UTM grids on them).

Finding Longitude

Published on by Jonathan Crowe

Book cover: Finding Longitude Major map exhibitions are frequently accompanied by lavishly illustrated books: London: A Life in Maps and the Magnificent Maps exhibitions had their eponymous books (London: A Life in Maps and Magnificent Maps), and the Chicago Festival of Maps was accompanied by Maps: Finding Our Place in the World.

No surprise, then, that “Ships, Clocks and Stars: The Quest for Longitude,” an exhibition opening at the National Maritime Museum in Greenwich next month, also has its accompanying volume: it’s called Finding Longitude: How Clocks and Stars Helped Solve the Longitude Problem, and it comes out later this week. It’ll be interesting to see how this complements Dava Sobel’s Longitude, a short history of the Longitude Prize and Harrison’s chronometers (my review).