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Almost two weeks ago, Dave Walden posted a link to this article in the Guardian: The forgotten maths genius who laid the foundations for Isaac Newton.

The article was inspired by a press release for a play on the life of Jeremiah Horrocks, the genius in question. The play is called Horrox, which was an alternate spelling. Bill Lionheart says that he saw the play a few days ago, but it left him with some questions. The article is filled with some extreme claims that are apparently supported by the play. So what did Horrocks actually do? How was Newton's work impacted by him? Horrocks certainly hasn't been forgotten. There's a plaque honoring him in Westminster Abbey, and there's a crater on the moon named in his honor. These are not small things. He was forgotten for a few decades after he died, especially during the era of the English Civil War(s). But he was acclaimed once again as an important astronomer in the 1660s following the publication of his work by the great astronomer Jan Hevelius (referred to dismissively in the Guardian article as "an appendage to a Polish astronomer's work"). 

One key claim in the article and apparently in the play is that Horrocks measured the scale of the Solar System by observing the parallax of Venus during the transit in 1639. He and his friend, William Crabtree, observed it simultaneously "on a cloudy day" in late 1639 with enough breaks in the clouds just before sunset to catch the exceedingly rare event. Crabtree was about 25 miles away. Bear in mind that Cook and the astronomers in 1769 had to travel to Tahiti to get an approximate measure of the scale of the Solar System by this method. But turns out you only have to go to the other side of Manchester! It seems that Horrocks didn't do anything remotely like what the play has claimed. He did not measure the distance to Venus. He did not "prove" that the Earth was not the center of the Cosmos. So what did he do? 

Newton certainly stood on the shoulders of giants, and I recently discovered a rare lithograph of Newton actually standing on the shoulders of some "intellectual" giants [see attached image]. Horrocks is not among them.

Frank Reed

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