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On Harriot’s astronomical observations contained in his unpublished manuscripts belonging to the Earl of Egremont

1837; Royal Society; Volume: 3; Linguagem: Inglês

10.1098/rspl.1830.0068

2053-9142

Stephen Peter Rigaud,

History of Science and Medicine

The reading of Professor Rigaud’s Paper was resumed and concluded. In the Memoirs of the Royal and Imperial Academy of Brussels, for the year 1788, the Baron de Zach published a paper on the planet Uranus, in a note to which he states that, in the summer of 1784, he found in the library of Lord Egremont at Petworth, some old manuscripts of the celebrated Thomas Harriot, which he alleges afforded proofs that he had observed the solar spots, and the satellites of Jupiter before Galileo. In the Berlin Ephemeris for 1788, Baron Zach gave a lull account of his alleged discovery, drawn up from Harriot’s papers; an English translation of which was circulated in this country, and has been perpetuated by its being inserted in Dr. Hutton’s Mathematical Dictionary. The author, having been entrusted by Lord Egremont with Harriot’s original papers, has examined them with every attention he could apply to the subject, and gives in the present memoir the result of his inquiry. The observations of Harriot on the spots on the sun, fill seventy-four half-sheets of foolscap, the first being dated December 8, 1610. These papers are in good preservation: the writing is clear, and the drawings well-defined. Baron Zach says, that “he compared the corresponding ones with those observed by Galileo, and found betwixt them an exact agreement.” This, the author shows, is very far from being the case, and he also brings evidence to prove that the discovery of the spots on the sun was made by Galileo at latest in the summer of the year 1610, and very probably in or before the month of July. He allows, however, that Harriot’s observation in December of the same year, was the result of his own spontaneous curiosity.