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TWILIGHT—TWISS, H.
  

in 1713, but the Perpendicular tower remains. Among men of eminence buried here are Alexander Pope and Sir Godfrey Kneller. The Thames in this neighbourhood forms a long deep reach in favour with fishermen, and Eel Pie Island is a resort of boating parties. There are many fine houses in the vicinity, more than one possessing historical associations. Strawberry Hill, the residence of Horace Walpole, was built to his taste in a medley of Gothic styles. Marble Hill was erected by George II. for the Countess of Suffolk, and Pope, Swift and Gay took part in its equipment. Orleans House was the residence in 1800 of Louis Philippe, then duke of Orleans, and this family again acquired it in 1852, when it was occupied by the duke of Aumale. Several eminent French refugees resided at this period in the neighbourhood. In 1700 the young duke of Gloucester, son of Queen Anne, died here. York House was given to Lord Clarendon by Charles II., was probably the occasional residence of James II. when duke of York, and in 1864 was occupied by the comte de Paris, nephew of the duke of Aumale. Twickenham House was the residence of Sir John Hawkins, author of the History of Music, and Twickenham Park House, no longer standing, that of Lord Chancellor Bacon. Pope’s Villa was replaced by another building after his death, but the tunnel which connected his garden and house beneath a road, and was ornamented by him as a grotto, remains. Other eminent residents were Turner, who occupied Sandycombe Lodge, and painted many of his famous works here, Henry Fielding the novelist, and Tennyson. Kneller Hall, the house built by Kneller (1711), was converted into a training college for masters of workhouse schools in 1847, and in 1856 became the Royal Military School of Music.

Twickenham at the Domesday survey was included in Isleworth. Anciently it was called Twittenham or Twicanham, and the first form, or a variation of it, is used by both Pope and Walpole. The manor was given in 941 by King Edmund to the monks of Christ Church, Canterbury, from whom it had been previously taken, but it was again alienated, for it was restored to the same monks by Edred in 948. In the reign of Henry VIII. it came into the possession of the Crown, and by Charles I. was assigned to Henrietta Maria as part of her jointure. It was sold during the Protectorate, but after the Restoration the queen mother resumed possession of it. In 1670 it was settled for life on Catherine of Braganza, queen of Charles II. It remains in possession of the Crown, but since the death of Catherine has been let on leases. The old manor house, now demolished, was Catherine's residence; and had been, according to tradition, the place of the retirement of Catherine of Aragon after her divorce from Henry VIII.


TWILIGHT, formerly known as Crepusculum (a Latin word meaning dusky or obscure), properly the interval during which the atmosphere is illuminated after the setting of the sun. The analogous phenomenon in the morning, i.e. the interval between the first appearance of light and the rising of the sun, is known as the dawn. These phenomena are due to the light of the sun after refraction by the atmosphere being reflected to the observer by the clouds, dust, and other adventitious matter present in the atmosphere. Even in the early infancy of astronomy, the duration of twilight was associated with the position of the sun below the horizon, and measurements were made to determine the maximum vertical depression of the sun which admitted the phenomena. This was found by Alhazen, Tycho Brahe and others, to be about 18°, and although other observers obtained somewhat different values, yet this value is now generally admitted. The duration of twilight is therefore measured by the time in which the sun traverses an arc of 18° of vertical depression, and primarily depends on the latitude of the observer and the declination of the sun. It is subject to several minor variations, occasioned by the variable amount of dust, clouds, &c. suspended in the air; and also on the temperature, which alters the altitude of the reflecting particles; thus at the same place and on the same day, the morning twilight or dawn is generally shorter than the evening twilight.

EB1911 - Volume 27.djvu

Fig. 1.

The duration and possibility of twilight may be geometrically exhibited as follows: Let O be the position of the observer (fig. 1); Z, the zenith; P, the pole of the heavens; ADB, the plane of the horizon; EDF, the path of the sun. Let the circles ADB and FDE intersect in the points D and D1; then these points correspond to the rising A and setting of the sun. Now twilight prevails from sunrise or sunset until the sun is depressed through 18°; hence if we draw arcs ZC and ZC1, equal to 108°, and terminating on the circle FDE at C and C1, then the arcs DC and D1C1 represent the distance traversed by the sun during the twilight. Also it may be observed that C1EC represents the path of the sun during the night, and DFD1 during the day. The arc CD is readily determined by spherical trigonometry. For, join CP by an arc of a great circle; then in the triangle ZPC we know ZP (the colatitude of O); PC (the sun’s polar distance) and ZC (=108° by construction). Hence the angle ZPC, the sun’s hour angle, may be found; this gives the time before or after noon when the sun passes C. The times of sunrise and sunset being known, then the arcs DC and D1C1 (and the duration of dawn and twilight) are determined.

So far we have considered the case when the sun does attain a depression of 18°, but it is equally possible for this depression not to be attained. To investigate this, take ZG equal to 108°. Now if G lies beyond B and E (the maximum depression of the sun), E being also below B, then the sun will rise and set, but never descend so low as to occasion true night, and the entire interval between sunrise and sunset will be twilight.

If E be not below, B but above it, the sun will never descend below the horizon, and will neither rise nor set, and we are presented with the phenomenon known as the midnight sun. Since PE=90°—sun’s declination, and PG=latitude of observer + 18°, then it follows that for there to be no night the latitude of the observer together with the declination of the sun must lie between 90° and 72°.

The maximum declination of the sun is about 23° 30′, and hence in latitude 48° 30′ there will be one day without a true night; in higher latitudes there will be an increasing number of such days; and in lower latitudes none. In England there is no real night from about the 22nd of May till the 22nd of July.

The phenomenon known as the after-glow, or second twilight, has been referred to a second reflection of the solar rays in the atmosphere.


TWILL (connected with “two”), a woven cloth in which the passage of the weft is arranged, not in regular succession as in plain weaving, but over one thread and under two or more according to the kind of twill. This gives a succession of diagonal lines to the cloth, and though in the normal type of twill this diagonal traverses from selvage to selvage at an angle of 45°, considerable variations may be made. Twills may be stout and serviceable cloths, though, theoretically, it would seem that the strain of wear on the threads that compose the cloth is necessarily irregular. The twill or diagonal may run either from left to right or vice versa. Twills are made in most kinds of cloths—silk, woollen, cotton, &c.


TWINING, THOMAS (1735–1804), English classical scholar, was born at Twickenham on the 8th of January 1734–1735. The son of Daniel Twining, tea merchant of London, he was originally intended for a commercial life, but his distaste for it and his fondness for study decided his father to send him to the university. He entered Sidney Sussex College, Cambridge (fellow, 1760), took orders, and after his marriage in 1764 spent the remainder of his life at Fordham (Essex) and Colchester, where he died on the 6th of August 1804. His reputation as a classical scholar was established by his translation, with notes, of Aristotle’s Poetics (1789). Twining was also an accomplished musician, and assisted Charles Burney in his History of Music.

Selections from his correspondence will be found in Recreations and Studies of a Country Clergyman of the Eighteenth Century (1882) and Selections from Papers of the Twining Family (1887)) edited by his grand-nephew (Richard Twining); see also Gentleman’s Magazine, lxxiv. 490, and J. E. Sandys, History of Classical Scholarship, vol. iii. (1908).


TWISS, HORACE (1787–1849), English writer and politician, was born at Bath, being the son of Francis Twiss (1760–1827), a Shakespearian scholar who married Mrs Siddons’s sister, Fanny Kemble, and whose brother Richard (1747–1821) made a name as a writer of travels. Horace Twiss had a pretty wit, and as a young man wrote light articles for the papers; and,