16 November 2011 by Tristan Gooley
In this photo, one of the Outward Bound Oman instructors, who I visited recently, is being taught how to use a traditional and beautifully simple navigational instrument called a ‘kamal’.
This instrument is as simple as they get: it works by forming a triangle. If you know the base of a triangle (the fixed length of twine from eye to instrument) and you know the height of the triangle (the number of fingers counted up from the horizon), then you have a fixed angle to the horizon. This is the ancestor of nearly all navigational instruments prior to electronics. (In fact the triangulation used has a lot in common with the way GPS works, but that is another story.)
How does it work in practice?
Here’s the simplest example: the Pole Star (Polaris, North Star) will be the same angle above your horizon as your latitude. At the North Pole…
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Tags: backstaff, equator, kamal, latitude, north pole, north star, octant, oman, polaris, Pole Star, sextant |
03 May 2010 by Tristan Gooley
I came across this fantastic map showing the direction of Mecca, known as ‘al Qiblah’, from different parts of the world.
It shows quite beautifully how counterintuitive it can be over the surface of a sphere. Who would have thought that the direction of Mecca, in Saudi Arabia, from New York is northeast? This is due to the fact that the direction is calculated using the shortest route and this is what is known as a great circle route. If you want to get from A to B across the surface of a sphere then the most direct route will always be a part of a circle which if continued would wrap itself all the way round the Earth, in a full circuference of the planet, and return to exactly the same point as you started at – a great circle. (This is the reason that airline route maps…
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Tags: al qiblah, direction, great circle, mecca, north pole, pacific |
In this photo, one of the Outward Bound Oman instructors, who I visited recently, is being taught how to use a traditional and beautifully simple navigational instrument called a ‘kamal’.
