If you're as big a geek as I am, you've often wondered how people found anything or got anywhere before Google Maps. I mean, how did Horatio Hornblower figure out if he was just entering the Bay of Biscay, rounding the Irish Sea or crawling straight up Napoleon's froggy wazoo?
He, and everybody else navigating the seas way back when, used a marine sextant, which gives rise to Thursday's picture of the day on Wikipedia. The animated GIF shows you how to use the marine sextant to determine your lattitude by sighting the sun at noon, the angle of which will vary with latitude. Couple that with a nice Rolex for fixing longitude -- which can be measured based on the difference between the celestial time wherever you are and absolute time usually measured to Greenwich Mean -- and you can leave your GPS at home... as long as it never gets cloudy.
Learning (in theory, at least) to use a sextant reminds me of the time my grandfather, who'd been an analyst in Reagan's California gubernatorial cabinet, tried to show a six-year-old yours truly how to use a slide rule. Dude, my brain is still hurting from that one.
Link and image via Wikipedia.
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