The English Mathematician Who Saw Sunspots Six Months Before Galileo and Published Nothing

Thomas Harriot (1560–1621) was an English mathematician, astronomer, and natural philosopher of the very first rank — and one of the most catastrophically unproductive publishers in the history of science. He was educated at Oxford, served as a mathematical tutor to Walter Raleigh in the 1580s (he sailed with the 1585 Roanoke voyage and produced the first published English description of the Algonquian peoples of coastal Carolina), and from 1598 until his death lived under the patronage of Henry Percy, the ‘Wizard Earl’ of Northumberland, at Syon House on the Thames west of London.

He produced original results in optics, astronomy, mathematics, and ballistics for forty years. He published almost none of them.

What he discovered

The list of substantial Harriot priorities the modern history of science has recovered from his unpublished manuscripts is uncomfortable reading for Galileo’s reputation. He observed the Moon telescopically on 26 July 1609 — four months before Galileo’s first published lunar observations of November 1609. He produced detailed sketches of the lunar surface that were substantially the equal of anything Galileo published in the Sidereus Nuncius of March 1610.

He observed sunspots in December 1610 — six months before the date conventionally given for Galileo’s priority and approximately the same time as the Frisian astronomer Johannes Fabricius. He maintained continuous sunspot observations through 1611-1613 with a better record-keeping discipline than Galileo’s; his surviving sunspot drawings preserve approximately 199 days of detailed observations of individual sunspot groups across the period.

He worked out the law of refraction — the sine-of-angle-of-incidence to sine-of-angle-of-refraction relationship — in approximately 1601, twenty years before Willebrord Snellius (after whom the law is conventionally named) rediscovered the same relationship in 1621. He had also developed algebraic notation that anticipated several major Cartesian-period innovations and had worked out approximately seventy specific mathematical results in algebra and analytic geometry that would have made him a first-rank European mathematician of the period if any of it had been published.

He published almost nothing.

Why he did not publish

The subsequent historical-philosophical reconstruction has produced several proposed explanations. The first is institutional. Harriot’s patron the 9th Earl of Northumberland was imprisoned in the Tower of London after the 1605 Gunpowder Plot (he was not directly implicated but was related to one of the conspirators and was held under preventive detention for sixteen years); his household at Syon Park, including Harriot, was under political suspicion through the remainder of the Jacobean reign. Publishing original natural-philosophical work under those conditions carried political risk that the safer Italian or Dutch publishing routes did not.

The second is personal-temperamental. Harriot’s surviving correspondence suggests a man uninterested in the competitive priority-claiming culture of early-modern European natural philosophy. He distributed unpublished manuscripts to a circle of English mathematical correspondents (Walter Warner, Robert Hues, Nathaniel Torporley, William Lower) who had access to most of his major results; he did not pursue international publication.

The third is medical. Harriot developed nasal cancer in approximately 1614 — the first documented English clinical description of the disease — which progressed slowly through the subsequent seven years and incapacitated him for publication preparation through the final years. He died at London in July 1621, aged about 61.

What was lost

Harriot’s manuscripts — approximately 8,000 pages of mathematical, astronomical, and optical work — were preserved by his executors and passed through several private collections through the 17th and 18th centuries. They were rediscovered in fragments through the 19th and 20th centuries; the comprehensive scholarly cataloguing was completed by the Harriot Seminar at the Open University between 1969 and the early 2000s.

The result is that the English contribution to the early Scientific Revolution is larger than the published record suggests. The conventional narrative — that Galileo, Kepler, and Descartes carried the decisive theoretical advances of the period — is substantively correct as a record of published priority but misleading as a record of original discovery.

Harriot’s sunspot data from 1611-1613 are now used by modern solar physicists as a supplementary input to the historical sunspot reconstructions that document the later Maunder Minimum of 1645-1715 and the earlier Spörer Minimum.