March 19th, 2019: Astrolabe

[xoxoxoBruce]

What’s that? No, not a Meth cooker in a Chevy Van, it’s the Sextant’s daddy, the navigators essential equipment before the end
of the 18th century. This is the oldest existing part of an Astrolabe. It came from a ship in Vasco da Gama’s fleet that went down
in a storm off the coast of Oman in 1503.

What is a mariner’s astrolabe?
The mariner's astrolabe was a simplified version of an instrument originally developed by Arab astronomers for measuring the height of heavenly bodies above the horizon and came into use in navigation by about 1470. In order to keep it steady when used on board ship, the mariner's version was heavier and had parts of the disc cut away to reduce wind resistance.

Who was the astrolabe invented by?
No one really knows for sure. The concept goes right back to the Roman Empire, and it has been claimed that it was invented by Hypatia of Alexandria, a female mathematician and philosopher who lived in Egypt in the 4th century AD. However, the idea of the astrolabe is certainly older than that, so it’s more likely that Hypatia was an expert in teaching about and improving the existing technology. The astrolabe was well known in the Islamic world during the Middle Ages and some of the great Muslim scientists made further improvements.

What? Muslim? Female mathematician & philosopher? No no, that won’t do, bury her in the backwaters of history.
Also make sure she isn’t going to crop up in textbooks.

In Europe they were highly prized tools and knowing how to use one was regarded as a bit of a status symbol. The English writer Geoffrey Chaucer, more famous for his Canturbury Tales, wrote A Treatise on the Astrolabe in 1391 which explained how to use the instrument and was possibly written for his son or godson.

Columbus had one aboard but the water was so rough it didn't do him much good.

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