There are one or two unimportant papers among the Torperley manuscripts that bear marks of having belonged to the Hariot papers, and there is a manuscript by Warner, entitled, ‘Certayne Definitions of the Planisphere.’ Any one curious in the history of Torperley may find in the Calendar of State Papers, Domestic Series, 1636, page 364, how his property was purloined by Mr Spencer, the first Librarian of Sion College. He was sued by Mistress Payne the administratrix and was compelled to disgorge £4.0 in money, eleven diamond rings, eight gold rings, two bracelets, etc. Then Archbishop Laud took away Spencer’s librarianship, and let him drop.
Mr William Spence of Greenock published in Nov. 1814, a work entitled, ‘Outlines of a Theory of Algebraical Equations deduced from the Principles of Harriott, and extended to the Fluxional or differential Calculus. By William Spence. London, for the Author, by Davis and Dickson, 1814, 8°, iv and 80 pages. Privately printed, intended ‘exclusively for the perusal of those gentlemen to whom it is addressed.’ He says in his prefatory note that—
‘As the principles are drawn from that theory of equations, by which Harriott has so far advanced the science of algebra.’ The author says, page I,’ Until the publication of Harriot’s Artis Analytica Praxis, no extended theory of equations was given. Harriot considered algebraical equations merely as analytical expressions, detached wholly from the operations by which they might be individually produced ; and, carrying all the terms over to one side, he assumed the hypothesis, that, as in that state the equation was equal to nothing, it could always be reduced to as many simple factors as there were units in the index of its highest power.’
Between 1606 and 1609 a very interesting and historically instructive correspondence took place between Kepler and Hariot upon several important scientific subjects. Five of the letters are given in full in ‘Joannis Keppleri Alio-rumque Epistolæ Mutuæ. [Frankfort] 1718,’ folio, to which the reader is referred, but a brief abstract of them may not be out of place here. The letters are numbered from 222 to 226 and fill pages 373 to 382. The correspondence was begun by Kepler:
Letter 122, dated Prague, 11 October, 1606, from John Kepler
to Thomas Hariot,
Kepler had heard of Hariot’s acquirements in Natural Philosophy from his friend John Eriksen. Would be glad to know Hariot’s views as to the origin and essential differences of colours; also on the question of refraction of rays of light; and the causes of the Rainbow; and of haloes round the sun.
Letter 223, dated London, 11 December, 1606,from
Thomas Hariot to John Kepler,
Had received with pleasure Kepler’s letter; but should not be able to answer it at length, being in indifferent health, so that it was not easy to write or even carefully to reflect. Sends a table of the results of experiments on equal bulks of various liquids and transparent solids (thirteen in number, including spring, rain, and salt water; Spanish and Rhenish wine; vinegar; spirits of wine; oils and glass). The angle of incidence is 30° in each case; also the specific gravity of each substance is given. Then he discusses the reason why refraction takes place. Promises to write on the Rainbow; but will merely say at present that it is to be explained by the reflection on the concave superficies and the refraction at the convex superficies of each separate drop.
Letter 224 is from John Kepler to Thomas Hariot, dated at Prague, 11 August, 1607.
Thanks Hariot for his table, which supplies matter for serious consideration. Asks questions as to how he defines the angles of incidence and refraction; and goes on to discuss the reasons of refraction. Agrees with Hariot as to his views about the Rainbow; but will be very glad to receive his treatises on Colours and the Rainbow.
Letter 225 is from Thomas Hariot to John Kepler, dated at Syon,
near London, 13 July (o.s.), 1608.
The departure of Eriksen and other matters do not allow leisure to write at length. The turpentine (oleum terebinth inum) was not the same as that experimented on by Kepler but a purer and lighter article (Sp. grav. ’87). The angle of incidence is understood as defined by Alhazen and Vitellio [first published 1572]. Points out some errors in Vitellio’s second table of refractions. As to the causes of refraction, Hariot believes in the theory of the vacuum; ‘where we still stick in the mud’. Hopes God (Deum optimum maximum) will soon put an end to this. Wishes for Kepler’s meteorological records for the last two years, and will send his own notes in return. Gilbert, author of a work on the magnet, had recently died, leaving in his brother’s hands a book entitled ‘De Globo et Mundo nostro sub lunari Philosophia nova contra Peripateticos, lib. 5." [A treatise, in five books, on Natural Philosophy, in answer to the Peripatetics.] The book is likely to be published before the end of the year. Hariot had read some chapters; and saw that Gilbert defends the doctrine of a vacuum. Not to leave a vacuum on this page (says Hariot), it is remarkable that though gold is both heavy and opaque, when beaten out into gold-leaf the light of a candle can be seen through it, though it appears of a green colour.
Letter 226, from John Kepler to Thomas Hariot, it dated from
Prague, September, 1609.
Excuses himself for not having replied sooner; having been very busy; but would not lose the present opportunity of writing. Discusses the questions of refraction and the vacuum. Commentaries on Mars entitled ‘Astronomia Nova [Greek Text] or Physica Cælestis,’ have been published at Frankfort; has not a copy by him. Regrets to hear of the death of Gilbert. Hopes his work on Magnetism will also be published; and that Erikson will bring a copy with him. Promises to send a copy of his own meteorological observations; and hopes to receive Hariot’s.
These studies in optics and this correspondence with the learned Kepler indicate Hariot’s great advancement in natural philosophy as early as 1606 to 1609 and give an earnest of his inventive genius and scientific enterprise with his telescope in the astronomical discoveries which immediately followed in 1609 to 1613. Before awarding all the prizes for discoveries and inventions in mathematics, philosophy and natural science to claimants throughout the wide Republic of Letters, let modest Hariot be heard and examined. Let his papers and all his credentials be laid out before the high court of science, not in the light of today, but contemporaneously with those of Tycho, Kepler, Galileo, Snell, Vieta and Descartes. Hariot himself has claimed nothing, but Justice and Historical Truth are bound to assign him a niche appropriate to his merits.
To show that Hariot, like his friends Hakluyt and Purchas, was alive to everything geographical as well as mathematical going on, the following is given from the original manuscript among the Hariot papers in the British Museum (Add. 6789):
Three reasons to prove that there is a passage from the North’ west into the South-sea.
1. The tydes in Port Nelson (where Sr. Tho : Button did winter, were constantly, 15, or, 18, foote ; wc is not found in any Bay Throughout the world but in such seas as lie open att both ends to the mayne Ocean.
2. Every strong Westerne winde did bring into the Harbor where he wintered, soe much water, that the Neap-tydes were equall to the Spring-tydes, notwtstanding yt the harbor was open only to ye E.N.E.