Mar 202011

William Herschell Looking to the Stars

A while ago on my ongoing series about nineteenth century heroines, we talked about Caroline Herschel, who learned astronomy from her famous brother, William Herschel (he discovered the planet Uranus, though he wanted to name it George), and went on to make many discoveries of her own. The nineteenth century was the time of the Grand Amateur—men and women who, by interest, ability, and fortune, made major contributions to the sciences like astronomy. There was something noble about discovering something new, whether it was a planet or the internal workings of a combustion engine.

Discovery wasn’t, however, easy.

In astronomy in particular, the tools were still plagued with difficulties. Many astronomers still studied the heavens through little more than spy glasses. Most available telescopes involved refracting light through carefully crafted glass lenses rather than reflecting it through mirrors. These lenses sometimes gave their images a colored glow about the edges, making it hard to observe some celestial phenomena. Telescopes that did reflect the light used speculum, metal made from bronze and silver to create a mirror-like substance. Unfortunately, it tarnished easily and distorted the image.William Herschel Telescope

In his quest for better viewing equipment, William Herschel learned to grind his own lenses,  coat his own mirrors, and make his own telescopes.  He started with smaller scopes, like this 7-footer . . .
then graduated to larger ones like this 20-foot goliath.

His skill was so great that other amateurs, including the King of Spain, commissioned scopes from him. Through a grant from King George III, he built a 40-foot-long telescope with a 49-inch mirror at his home in Slough, near Windsor, in what would be called Observatory House. It was the largest telescope in the world at the time, and a source of many visitors, until the Earl of Roth, an Irish peer, build a larger scope in 1845.

But even these mammoth scopes had problems. They were often mounted in such a way that turning them was difficult. If you were lucky, the dais on which they were built could be hand-cranked to swivel the telescope both horizontally and vertically, but this positioning could take hours or days. So basically you could watch a single slice of sky on a given night with a larger scope, which was not conducive to scanning the skies for anomalies or hunting comets.

And why would you want to hunt comets, you ask? That was one of the most exciting aspects of astronomy, your chance to make a name for yourself, to go down in history. All comets discovered during the early nineteenth century were first sighted with the naked eye, so anyone could get into the game.

Posted with permission of the author.

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