Ditton, Humphrey (DNB00)

From Wikisource
Jump to: navigation, search

DITTON, HUMPHREY (1675–1715), mathematician, was born at Salisbury on 29 May 1675, being, it is said, the fourteenth of the same name in a direct 1ine. His mother belonged to the family of the Luttrells of Dunster Castle, Taunton, and brought a fortune to his father, who nearly ruined himself by contending in support of the nonconformists. He sent his only son, however, to be educated by a clergyman, Dr. Olive. The younger Ditton afterwards became a dissenting preacher at his father's desire, and preached for some years at Tunbridge. Here he married a Miss Ball. His energy injured his health, and after his father's death he gave up the ministry. In 1705 he published a short exposition of the fundamental theorems of Newton's ‘Principia.’ In 1706 he was appointed through Newton's influence master of a new mathematical school at Christ's Hospital. The school was discontinued after his death as a failure. William Whiston [q. v.] happened to mention in Ditton's company that he had heard at Cambridge the guns fired in the action off Beachy Head. This suggested a scheme for determining the longitude, to which an addition was made by Whiston on seeing the fireworks for the peace of Utrecht, 7 July 1713. The longitude might be ascertained by firing a shell timed to explode at a height of 6,440 feet. The time between the flash and the sound would give the distance to any ships within range. As the Atlantic, according to their statement, is nowhere more than three hundred fathoms deep, fixed stations might be arranged. The friends advertised their invention in the ‘Guardian’ of 14 July and the ‘Englishman’ of 10 Dec. 1713. They laid their scheme before Newton, Samuel Clarke, Halley, and Cotes. A committee of the house sat upon the question, and an act was passed in June 1714 offering a reward of from 10,000l. to 20,000l. for the discovery of a method successful within various specified degrees of accuracy. Arbuthnot, in a letter to Swift on 17 July 1714, ridicules the plan, declaring that it anticipated a burlesque proposal of his own intended for the ‘Scriblerus Papers,’ and Swift made it the occasion of a song with unsavoury rhymes upon Whiston and Ditton. The plan, however, was laid before the board of longitude, which rejected it. Though it is said that the principle has been applied to determine the distance between Paris and Vienna, its absurdity for practical purposes in navigation is sufficiently obvious. The German translator of Ditton's book on the ‘Resurrection’ says that he corresponded with Leibnitz upon the use of chronometers in determining the longitude, and sent him the design for a piece of clockwork. This method, however, is pronounced to be hopeless in his pamphlet. Ditton died on 15 Oct. 1715, when the matter was still unsettled (see 2nd ed. of New Method); it is therefore more probable that he died of ‘a putrid fever’ than of disappointment. The ‘Gospel Magazine’ for September 1777 (pp. 393–403, 537–41) gives a diary of Ditton's, consisting exclusively of religious meditations.

Ditton's works are:

  1. ‘On Tangents of Curves deduced from Theory of Maxima and Minima,’ ‘Philosophical Transactions,’ vol. xxiii. p. 1333.
  2. ‘Spherical Catoptrics’ (ib. xxiv. 1810); translated in ‘Acta Eruditorum’ for 1705, and ‘Memoirs of Academy of Sciences at Paris.’
  3. ‘The General Laws of Nature and Motion,’ 1705.
  4. ‘An Institution of Fluxions, containing the first principles, operations, and applications of that admirable method as invented by Sir Isaac Newton,’ 1706 (2nd ed. revised by John Clarke, 1726).
  5. ‘A Treatise of Perspective, demonstrative and practical,’ 1712 (superseded by Brook Taylor's treatise, 1715).
  6. ‘A Discourse concerning the Resurrection of Jesus Christ’ (a discussion of the principles of ‘moral evidence,’ with an appendix arguing that thought cannot be the product of matter), 1714, 4th ed. 1727, and German and French translations.
  7. ‘The new Law of Fluids, or a discourse concerning the Ascent of Liquids, in exact geometrical figures, between two nearly contiguous surfaces,’ 1714. To this is appended a tract, printed in 1713, entitled ‘Matter not a Cogitative Substance,’ and an advertisement about the longitude project.
  8. ‘New Method for discovering the Longitude both at Sea and Land’ (by Whiston and Ditton), 1714, 2nd ed. 1715.

[Biog. Brit.; Trollope's Hist. of Christ's Hospital; Whiston's Memoirs.]

L. S.