maker. Knight was in the habit of certifying each instrument by signing his name on the card. There is a compass preserved in the admiralty compass department at Deptford certified in this way. It is stated by Captain Flinders in a manuscript diary, now in the possession of his descendant, Mr. Flinders Petrie, that Knight occupied the position of inspector of compasses to the admiralty, and that J. H. de Magelhaens was his successor in the office. Captain Flinders had every opportunity of knowing the facts, but the statement is not borne out by the admiralty minute books. In 1766 Knight took out a patent (No. 850) for some further improvements in compasses, the main object of which was to check the vibration, the card and box being made to oscillate in equal times, so that the card always remained parallel to the glass. A reflecting azimuth compass is also described in the specification of this patent. The value of Knight's services to navigation does not seem to have received adequate recognition. A useful summary of Knight's work in this department of science is given in Snow Harris's ‘Rudimentary Magnetism,’ 1852, chap. ix.
Knight was an unsuccessful candidate for the post of secretary to the Royal Society in 1752, in opposition to Dr. Birch. But when the British Museum was first established at Montague House, Bloomsbury, in 1756, he was appointed principal librarian. The salary attached to the office was only 160l. per annum, but the librarian was allowed to act also as ‘receiver,’ and received on that account an additional 40l. a year. He presented to the museum a set of his magnetical apparatus (which were shown in the early days of the institution, but cannot now be found), the Copley medal which he received from the Royal Society in recognition of his magnetical researches, and a collection of coins and medals bequeathed to him by his father. There are two papers in his hand among the Sloane MSS., one relating to alchemy and the other being notes of lectures on surgery, but without any indication of the time and place of delivery.
He seems to have led a secluded life, and during his later years was involved in financial difficulties. Dr. John Fothergill on one occasion advanced him a thousand guineas to save him from impending ruin due to some disastrous mining speculations (Fothergill, Works, ed. Lettsom, vol. i. p. ciii), and Knight was never able to discharge this liability. By his will, dated 9 April 1772, he left everything to his ‘good friend and principal creditor, John Fothergill of Harpur Street,’ whom he appointed sole executor. It appears from the official records that Knight died at the museum on 8 June 1772 (not 9th, as in Gent. Mag. 1772, p. 295). His burial is recorded in the registers of St. George's, Bloomsbury, a few days afterwards, but it is probable that he was interred in the parochial cemetery near the Foundling Hospital. There is a portrait of him in the board room at the museum presented by his executor. It was probably painted by Benjamin Wilson, with whom he was on terms of intimacy, but it is not the original of the small etching in the Rembrandt manner bearing the inscription, ‘Painted and etched by B. Wilson, 1751,’ which is well known to collectors.
Although the bent of Knight's genius was decidedly experimental and practical, he published a speculative treatise in 1748 entitled ‘An Attempt to demonstrate that all the Phenomena in Nature may be explained by two simple active principles, Attraction and Repulsion, wherein the attractions of Cohesion, Gravity, and Magnetism are more particularly explained.’ The book consists of ninety-one propositions, and is of interest as showing marks of an epoch in which attempts were made to push the Newtonian doctrine into molecular speculations. It preceded Boscovich's better-known work on a similar subject by ten years. Knight also wrote a paper on the earthquake of 8 Feb. 1749–50 (Phil. Trans. xlvi. 603) and some remarks on W. Mountaine's letter on the effects of lightning (ib. li. 294). He was the inventor of ‘dwarf venetian blinds,’ which have since been largely used. He obtained a patent for the invention in 1760 (No. 750).
[Authorities cited; Foster's Alumni Oxonienses; Bloxam's Registers of Magdalen College, vi. 241; Nichols's Literary Illustrations, viii. 626; Nichols's Literary Anecdotes, v. 534; Athenæum, 6 Jan. 1849 pp. 5, 6, 15 Oct. 1849 p. 495; De Morgan in Notes and Queries, 2nd ser. x. 281.]
KNIGHT, HENRIETTA, Lady Luxborough (d. 1756), friend of Shenstone, was the only daughter of Henry, viscount St. John, by his second wife, Angelica Magdalena, daughter of Georges Pillesary, treasurer-general of the marines, and superintendent of the ships and galleys of France under Louis XIV. Henry St. John, first viscount Bolingbroke, [q. v.], was her half-brother. She married, on 20 June 1727, Robert Knight of Burrells, Warwickshire, eldest son of Robert Knight, cashier of the South Sea Company, created in 1746 Baron Luxborough of Shannon, and in 1763 Viscount Barrells and Earl of Catherlough in the peerage of Ireland. Horace Walpole describes her as 'high-coloured' and 'lusty,' with a 'great black bush of hair,' in
