HARRIOT (Thomas)

, a very eminent English mathematician and astronomer, was born at Oxford in 1560, and died at London July 2, 1621, in the 61st year of his age. Harriot has hitherto been known to the world only as an algebraist, though a very eminent one; but from his manuscript papers, that have been but lately discovered by Dr. Zach, astronomer to the duke of Saxe-Gotha, it appears that he was not less eminent as an astronomer and geometrician. Dr. Zach has printed an account of those papers, in the Astronomical Ephemeris of the Royal Academy of Sciences at Berlin, for the year 1788; of which, as it is very curious, and contains a great deal of information, I shall here give a translation, to serve as memoirs concerning the life and writings of this eminent man; afterwards adding only some necessary remarks of my own.

“I here present to the world (says Dr. Zach), a short account of some valuable and curious manuscripts, which I found in the year 1784, at the seat of the earl of Egremont, at Petworth in Sussex, in hopes that this learned and inquisitive age will either think my endeavours about them worthy of its assistance, or else will be thereby induced to attempt some other means of publishing them. The only undeniable proof I can now produce of the usefulness of such an undertaking, is by giving a succinct report of the contents of these materials, and briefly shewing what may be effected by them. And although I come to the performance of such an enterprize with much less abilities than the different parts of it require, yet I trust that my love for truth, my design and zeal to vindicate the honour due to an Englishman, the author of these manuscripts, which are the chief reasons that have influenced me in this undertaking, will serve as my excuse.

“A predecessor of the family of lord Egremont, viz, that noble and generous earl of Northumberland, named Henry Percy, was not only a generous favourer of all good learning, but also a patron and Mæcenas of the learned men of his age. Thomas Harriot, the author of the said manuscripts, Robert Hues (well known by his Treatise upon the Globes), and Walter Warner, all three eminent mathematicians, who were known to the earl, received from him yearly pensions; so that when the earl was committed prisoner to the Tower of London in the year 1606, our author, with Hues and Warner, were his constant companions; and were usually called the earl of Northumberland's three Magi.

“Thomas Harriot is a known and celebrated mathematician among the learned of all nations, by his excellent work, Artis Analyticæ Praxis, ad æquationes algebraicas nova expedita & generali methodo, resolvendas, Tractatus posthumus; Lond. 1631: dedicated to Henry earl of Northumberland; published after his death by Walter Warner. It is remarkable, that the fame and the honour of this truly great man were constantly attacked by the French mathematicians; who could not endure that Harriot should in any way diminish the fame of their Vieta and Des Cartes, especially the latter, who was openly accused of plagiarism from our author. [See Montucla's Histoire des Mathematiques, part 3, p. 485 & seq.—Lettres de M. Des Cartes, tom. 3, pa. 457, edit. Paris 1667, in 4to.—Dictionnaire de Moreri, word Harriot.—Encyclopedie, word Algebra.—Lettres de M. de Voltaire, sur la nation Angloise, lettre 14. —Memoire de l'Abbé de Gua dans les Mem. de l'Acad. des Sciences de Paris pour 1741.—Jer. Collier's great Historical Dictionary, word Harriot.—Dr. Wallis's preface to his Algebra.—To which may be added the article Algebra, in this dictionary.]

“Des Cartes published his Geometry 6 years after Harriot's work appeared, viz, in the year 1637. Sir Charles Cavendish, then ambassador at the French court at Paris, when Des Cartes's Geometry made its first appearance in public, observed to the famous geometrician Roberval, that these improvements in Analysis had been already made these 6 years in England, and shewed him afterwards Harriot's Artis Analyticæ Praxis, which as Roberval was looking over, at every page he cried out, Oui! oui! il l'a vu! Yes! yes! he has seen it! Des Cartes had also been in England before Harriot's death, and had heard of his new improvements and inventions in Analysis. A critical life of this man, which his papers would enable me to publish, will shew more clearly what to think upon this matter, which I hope may be discussed to the due honour of our author.

“Now all this relates to Harriot the celebrated analyst; but it has not hitherto been known that Harriot was an eminent astronomer, both theoretical and practical, which first appears by these manuscripts; among which, the most remarkable are 199 observations of the Sun's Spots, with their drawings, calculations and determinations of the sun's rotation about his axis. There is the greatest probability that Harriot was the first discoverer of these spots, even before either Galileo or Scheiner. The earliest intelligence we have of the first discovered solar spots, is of one Joh. Fabricius Phrysius, who in the year 1611 published at Wittemberg a small treatise, intitled, De Maculis in Sole observatis & apparente eorum cum Sole conversione narratio. Galileo, who is commonly accounted the first discoverer of the Solar Spots, published his book, Istoria e Dimonstrazioni intorne alle Machie Solare e loro accidenti, at Rome, in the year 1613. His first observation in this work, is dated June 2, 1612. Angelo de Filiis, the editor of Galileo's work, who wrote the dedication and preface to it, mentions, pa. 3, that Galileo had not only discovered these spots in the month of April in the year 1611, at Rome, in the Quirinal Garden, but had shewn them several months before (molti mesi innanzi) to his friends in Florence. And that the observations of the disguised Apelles (the Jesuit Scheiner, a pre-| tender to this first discovery) were not later than the month of October in the same year; by which the epoch of this discovery was fixed to the beginning of the year 1611. But a passage in the first letter of Galileo's works, pa. 11, gives a more precise term to this discovery. Galileo there says in plain terms, that he had observed the Spots in the Sun 18 months before. The date of this letter is May 24, 1612; which brings the true epoch of this discovery to the month of November, 1610. However, Galileo's first produced observations are only from June 2, 1612, and those of father Scheiner of the month of October, in the same year. But <*>now it appears from Harriot's manuscripts, that his first observations of these Spots are of Dec. 8, 1610. It is not likely that Harriot could have this notice from Galileo, for I do not find this mathematician's name ever quoted in Harriot's papers. But I find him mentioning Josephus a Costa's book 1, chap. 2, of his Natural and Moral History of the West Indies, in which he relates that in Peru there are Spots to be seen in the Sun which are not to be seen in Europe. It rather seems that Harriot had taken the hint from thence. Besides, it is very likely that Harriot, who lived with so generous a patron to all good learning and improvements, had got the new invention of telescopes in Holland much sooner in England, than they could reach Galileo, who at that time lived at Venice. Harriot's very careful and exact observations of these Spots, shew also that he was in possession of the best and most improved telescopes of that time; for it appears he had some with magnifying powers of 10, 20, and 30 times. At least there are no earlier observations of the Solar Spots extant than his: they run from December 8, 1610, till January 18, 1613. I compared the corresponding ones with these observed by Galileo, between which I found an exact agreement. Had Harriot had any notion about Galileo's discoveries, he certainly would have also known something about the phases of Venus and Mercury, and especially about the singular shape of Saturn, first discovered by Galileo; but I find not a word in all his papers concerning the particular figure of that planet.

“Of Jupiter's Satellites. I found among his papers a large set of observations, with their drawing, position, and calculations of their revolutions and periods. His first observation of those discovered Satellites, I find to be of January 16, 1610; and they go till February 26, 1612. Galileo pretends to have discovered them January 7, 1610; so that it is not improbable that Harriot was likewise the first discoverer of these attendants of Jupiter.

“Among his other observations of the Moon, of some Eclipses, of the planet Mars, of Solstices, of Refraction, of the Declination of the Needle; there are most remarkable ones of the noted Comets of 1607, and of 1618, the latter, for there were two this year (see Kepler de Cometis, pa. 49). They were all observed with a cross-staff, by measuring their distances from fixed stars; whence these observations are the more valuable, as comets had before been but grossly observed: Kepler himself observed the comet of 1607 only with the naked eye, pointing out its place by a coarse estimation, without the aid of an instrument; and the elements of their orbits could, in defect of better observa- tions, be only calculated by them. The observations of the comet of the year 1607, are of the more importance, even now for modern astronomy, as this is the same comet that fulsilled Dr. Halley's prediction of its return in the year 1759. That prediction was only grounded upon the elements afforded him by these coarse observations; for which reason he only assigned the term of its return to the space of a year. The very intricate calculations of the perturbations of this comet, afterwards made by M. Clairaut, reduced the limits to a month's space. But a greater light may now be thrown upon this matter by the more accurate observations on this comet by Mr. Harriot. In the month of October 1785, when I conversed upon the subject of Harriot's papers, and especially on this comet, with the very celebrated mathematician M. de la Grange, director of the Royal Academy of Sciences at Berlin; he then suggested to me an idea, which, if brought into execution, will clear up an important point in astronomy. It is well known to astronomers how difficult a matter it is, to determine the mass, or quantity of matter, in the planet Saturn; and how little satisfactory the notions of it are, that have hitherto been formed. The whole theory of the perturbations of comets depending upon this uncertain datum, several attempts and trials have been made towards a more exact determination of it by the most eminent geometricians of this age, and particularly by la Grange himself; but never having been satisfied with the few and uncertain data heretofore obtained for the resolution of this problem, he thought that Harriot's observations on the comet of 1607, and the modern ones of the same comet in 1759, would suggest a way of resolving the problem a posteriori; that of determining by them the elements of its ellipsis. The retardation of the comet compared to its period, may clearly be laid to the account of the attraction and perturbation it has suffered in the region of Jupiter and Saturn; and as the part of it belonging to Jupiter is very well known, the remainder must be the share which is due to Saturn; from whence the mass of the latter may be inferred. In consequence of this consideration I have already begun to reduce most of Harriot's observations of this comet, in order to calculate by them the true elements of its orbit on an elliptical hypothesis, to complete M. la Grange's idea upon this matter.

“I forbear to mention here any more of Harriot's analytical papers, which I found in a very great number. They contain several elegant solutions of quadratic, cubic, and biquadratic equations; with some other solutions and loca geometrica, that shew his eminent qualifications, and will serve to vindicate them against the attacks of several French writers, who refuse him the justice due to his skill and accomplishments, merely to save Des Cartes's honour, who yet, by some impartial men of his own nation, was accused of public plagiarism.

“Thomas Harriot was born at Oxford, in the year 1560. After being instructed in the rudiments of languages, he became a commoner of St. Mary's-Hall, where he took the degree of bachelor of arts in 1579. He had then so distinguished himself by his uncommon skill in mathematics, as to be recommended soon after to Sir Walter Raleigh, as a proper preceptor to him in that science. Accordingly that noble knight became his first patron, took him into his family, and allowed| him a handsome pension. In 1584 he went over with Sir Walter's first colony to Virginia; where he was employed in discovering and surveying the country, &c; maps of which I have found (says Dr. Zach) very n<*>atly done among his papers. After his return he published A Brief and True Report of the Newfoundland of Virginia, of the Commodities there sound to be raised, &c; Lond. 1588. This was reprinted in the 3d volume of Hakluyt's Voyages: it was also translated into Latin, and printed at Frankfort in the year 1590. Sir Walter introduced him to the acquaintance of the earl of North<*>berland, who allowed him a yearly pension; Wood says, of 120l. only; but by some of his receipts, which I have found among his papers, it appears that he had 300l, which indeed was a very large sum at that time. Wood, in his Athen. Oxon. mentions nothing of Harriot's papers, except a manuscript in the library at Sion College, London, entitled Ephemeris Chyrometrica. I got access to this library and manuscripts, and was indeed in hopes of finding something more of Harriot's; for most of his observations are dated from Sion College; but I could not find any thing from Harriot himself. I found indeed some other papers of his friends: he mentions, in his observations, one Mr. Standish, at Oxford, and Nicol. Torperly, who also was of the acquaintance of the earl of Northumberland, and had a yearly pension: from the former I found two observations of the same comet of 1618, made in Oxford, which he communicated to Mr. Harriot.

“Thomas Harriot died July 2, 1621. His disease was a cancerous ulcer in the lip, which some pretend he got by a custom he had of holding the mathematical brass instruments, when working, in his mouth. I found several of his letters, and answers to them, from his physician Dr. Alexander Rhead, who in his treatise mentions Harriot's disease. His body was conveyed to St. Christopher's church, in London. Over his grave was soon after erected a monument, with a large inscription, which was destroyed with the church itself by the dreadful fire of September 1666. He was but 60 years of age.”

The peculiar nature and merits of Harriot's Algebra, we have spoken largely and particularly of, under the art. Algebra, page 89. As to his manuscripts lately discovered by Dr. Zach, as above mentioned, it is with pleasure I can announce, that they are in a fair train to be published: they have been presented to the university of Oxford, on condition of their printing them; with a view to which, they have been lately put into the hands of an ingenious member of that learned body, to arrange and prepare them for the press.