(Thomas) was a very eminent mathematician of the 16th and 17th centuries, of whom some account has been given in the Encyclopaedia Britannica. In that article it has been shewn, that Des Cartes had seen some improvements of Harriot's in algebra, and published them to the world as his own; but this piece of plagiarism has been more completely proved in the Astronomical Ephemeris for the year 1638, by Dr Zach, astronomer to the Duke of Saxe-Gotha; who likewise shews that Harriot was an astronomer as well as an algebraist.

"I here present to the world (says the Doctor) 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.

"A predecessor of the family of lord Egremont, viz. that noble earl of Northumberland, named Henry Percy, was not only a generous favourer of all good learning, but also a patron and Mecenas 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 Analyticae Praxis, ad equationes algebraicas novas 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.

"Des Cartes published his Geometry six years after Harriot's work appeared, viz. in the year 1637. Sir Charles Cavendish, then ambassador at the French court..." at Paris, observed to the famous geometrician Roverval, that these improvements in analysis had been already made there six years in England; and shewed him afterwards Harriot's Artis Analyticae Praxis; which, as Roverval was looking over, at every page he cried out, Oui! oui! il l'a vu! Tres bien! he has seen it! Descartes had also been in England before Harriot's death, and had heard of his new improvements and inventions in analysis.

"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. Fabrius Phrygus, who in the year 1611 published at Wittenberg a small treatise, intitled, De Maculis in Sole observatis & apparente eorum cum Sole convegione narratio. Galileo, who is commonly accounted the first discoverer of the solar spots, published his book, Ilfloria e Dimostrazioni intorno alle Macchie Solari e loro occidenti, at Rome in the year 1613. His first observation in this work is dated June 2d 1612. Angelo de Filis, the editor of Galileo's work, who wrote the dedication and preface to it, mentions, page 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 dignified Apelles (the Jesuit Scheiner, a pretender 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 fifth letter of Galileo's works, p. 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 quoting book i. chap. 2. of Joseph a Colla's 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 seen in Europe; and hence it is probable, that Harriot took the hint of looking for such spots. Besides, it is not unlikely, that living with so munificent a patron, Harriot got from Holland the new invented telescopes much sooner 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 those 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 angular shape of Saturn, first discovered by Galileo; but I find not a word in all his papers concerning the particular figure of that planet.

"I found likewise (continues Dr Zach) among the papers of Harriot a large set of observations on the satellites of Jupiter, with drawings of them, their positions, 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 eclipses, of the planet Mars, of solstices, of refraction, of the declination of the needle, &c. there are remarkable ones of the comet of 1607, and the latter comet (for there were two) of 1618. 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 observations, 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 fulfilled Dr Halley's prediction of its return in the year 1759. That prediction was only grounded upon the elements afforded him by these crude 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 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 geometers of this age, and particularly by la Grange himself; but never having been satisfied with the few and uncertain data heretofore obtained for the revolution 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 Hasselquist 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; 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. de 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 Descartes' honour, who yet, by some impartial men of his own nation, was accused of public plagiarism."

Hasselquist (Frederick) was born in the province of East Gothland in 1722, and studied medicine and botany in the university of Upsal. Linnaeus had in his lectures represented the extraordinary merits and great celebrity which a young student might obtain by travelling through Palestine, and by inquiring into and describing the natural history of that country, which was still then unknown, and had become of the greatest importance to interpret the Bible, and to understand eastern philology. Hasselquist was fired with ambition to accomplish an object so important in itself, and so warmly recommended by his beloved master. There being no fund arising from the liberality of the crown, private collections were made, which poured in very copiously, especially from the native country of the young traveller. All the faculties of the university of Upsal also granted him a stipend.

Thus protected, he commenced his journey in the summer of 1749. By the interference of Lagerstroem, he had a free passage to Smyrna in one of the Swedish East Indiamen. He arrived there at the conclusion of the year, and was received in the most friendly manner by Mr A. Rydel, the Swedish consul. In the beginning of 1750 he set out for Egypt, and remained nine months at Cairo the capital. Hence he went to Linnaeus, and to the learned societies of his country, some specimens of his researches. They were published in the public papers, and met with the greatest approbation; and upon the proposition of Dean Baeck and Dr Wargentin, secretary of the Royal Academy of Sciences, a collection of upwards of 10,000 dollars in copper money was made for the continuance of the travels of young Hasselquist. Counsellors Lagerstroem and Nordecrantz were the most active in raising subscriptions at Stockholm and Gothenburgh. In the spring of 1751, he repaired to his destination, and passed through Jaffa to Jerusalem, Jericho, &c. He returned afterwards through Rhodes and Scio to Smyrna. Thus he fulfilled all the expectations of his country, but he was not to reap the reward of his toils. The burning heat of the sandy deserts of Arabia had affected his lungs; he reached Smyrna in a state of illness, in which he languished for some time, and died February 9, 1752, in the 30th year of his age.

The fruits of his travels were, however, preserved through the liberality of a great princess. He had been obliged to contract debts. The Turks, therefore, seized upon all his collections, and threatened to expose them to public sale. The Swedish consul prevented it. He sent, with the intelligence of the unhappy exit of his countryman, an account of the difficulties under which he died; and at the representation of Dean Baeck, Queen Louisa Ulrica granted the sum of 14,000 dollars in copper specie to redeem all his collections. They arrived afterwards in good preservation at Stockholm; consisting of a great quantity of antiques, Arabian manuscripts, shells, birds, serpents, insects, &c., and were kept in the cabinets at Ulriksdals and Drottningholm. The specimens of the natural curiosities of these museums being double or treble in number, Linnaeus obtained some of them, and published the voyage of his ill-fated friend, and honoured his memory with a plant, which he called from his name Hasselquillia. Hasselquist, Encycl.