the dividing a thing into three equal parts. The term is chiefly used in geometry, for the division of an angle into three equal parts. The trisection of an angle geometrically, is one of those great problems, whose solution has been so much sought for by mathematicians for 2000 years past; being, in this respect, on a footing with the famous quadrature of the circle, and the duplication of the cube.

TRISTAN n'ACUNHA, the largest of three islands which were visited by Lord Macartney and his suite on the 31st of December 1792. The other two are distinguished by the names of Inaccessible and Nightingale islands. "Inaccessible (as Sir Erasmus Gower observed) seems to deserve that name, being a high, bluff, as well as apparently barren plain, about nine miles in circumference, and has a very forbidding appearance. There is a high rock detached from it at the south end. Its latitude is 37° 10' south; its longitude 11° 50' west from Greenwich. This rude-looking spot may be seen at 12 or 14 leagues distance. Nightingale island is irregular in its form, with a hollow in the middle, and is about seven or eight miles in circumference, with small rocky islets at its southern extremity. It is described as having anchorage on the north-east side. Its latitude is 37° 29' south; and longitude 11° 48' west from Greenwich. It may be seen at seven or eight leagues distance. The largest of these three islands, which comparatively may be called the great isle of Tristan d'Acunha, is very high, and may be seen at 25 leagues distance. It seems not to exceed in circumference 15 miles. A part of the island towards the north rises perpendicularly from the sea to a height apparently of a thousand feet or more. A level then commences, forming what among seamen is termed table land, and extending towards the centre of the island; from whence a conical mountain rises, not unlike in appearance to the Peak of Teneriffe, as seen from the bay of Santa Cruz. Boats were sent to sound and to examine the shore for a convenient place to land and water. In consequence of their report, the Lion (a ship of 64 guns) stood in, and came to anchor in the evening on the north side, in 30 fathoms water, one mile from the shore; the bottom black sand with flint; a small rock, off the west point, bearing south-west by south, jutting open with the western extremity of the island; a cove, or fall of water, emptying itself upon the beach, south by east. All the shore, from the southern point to the eastern extremity, appears to be clear of danger, and steep, except the west point, where there are breakers about two cables length, or near 300 yards from the shore. The ship, when anchored, was overshadowed by the dark mass of that portion of the island whose sides seemed to rise, like a moss grown wall, immediately from the ocean. On the right the elevation was less rapid, and between the rising part and the sea was left a flat, of some extent, covered with sedge-grass, intermixed with small shrubs, which, being perfectly green, looked from the ship like a pleasant meadow, watered by a stream that fell, afterwards, from its banks upon the beach. The officers, who went ashore, reported, that the casks might be filled with fresh water by means of a long hose, without moving them from the boats. The landing-place thereabouts was also described as being safe, and superior to any other that had been examined. From the plain, the land rose gradually towards the central mountain, in ridges covered with trees of a moderate size and height. The coast abounded with sea lions and seals, penguins and albatrosses. One of the latter was brought on board, his wings measuring ten feet from tip to tip; but others are said to have been found much larger. The coast was covered with a broad sea-weed, several fathoms long, and deservedly by naturalists termed gigantic fucus. Some good fish was caught with the hook and line.

"The accident of a sudden gulf, by which the anchor was in a few hours driven from its hold, and the ship forced out to sea, prevented the island from being explored, as was intended. It is probable that had the Lion anchored in 20, instead of 30 fathoms water, the anchor would have held firmly. Some advantage was obtained, however, from coming to this place. The just position of those islands, in respect to their longitude, was ascertained, by the mean of several time-pieces, to be about two degrees to the eastward of the place where they are laid down in charts, taken from observations made at a period when the instruments for this purpose were less accurate than at present. The spot where the Lion anchored was determined, by good meridional observations, and by accurate time-pieces, to be 37° 6' south latitude, and 11° 43' west longitude from Greenwich. The compass had seven degrees of variation westward from the pole. Fahrenheit's thermometer stood at 67 degrees. It was useful also to have ascertained, that a fine anchorage, and plenty of good water, were to be found here. These islands are certainly worthy of a more particular inquiry; for they are not 50 leagues from the general track of ve- TRO

Tristan fels bound to China, and to the coast of Coromandel, by the outer passage. In war time, an excellent rendezvous might be settled there, for ships that wanted no other supply but that of water. When circumstances require particular dispatch, it is practicable to come from England to Tristan d'Acunha without stopping in the way, and afterwards to the end of the voyage to India or China.

These islands are separated by a space of about fifteen hundred miles from any land to the westward or northward of them. They are situated in that part of the southern hemisphere, in the neighbourhood of which a continent, to balance the quantity of land in the northern hemisphere, was once expected to be found, but where it has been since discovered that there is none. Of what extent, however, the bases of these islands are under the surface of the sea, cannot be ascertained; or whether they may, or may not, be sufficient to make up for the defect of land appearing above water. Navigators report, that to the eastward of them are other small islands, differing not much in latitude, such as Gough and Alvarez islands, and the Marquesas; as well as extensive shoals, lying due south of the most southerly point of Africa, and extending easterly several degrees. That all these together form a chain, some of subsaqueous, and some of superaqueous mountains, but all connected by their roots, is perhaps a conjecture less improbable, than that they should separately arise, like tall columns, from the vast abyss.

A settlement in Tristan d'Acunha is known to have been twice in the contemplation of adventurers, but not as yet to have been carried into execution. One had the project of rendering it a mart for the change of the light manufactures of Hindoostan, suited to hot climes, for the silver of the Spanish settlements in South America; in the route between which places it is conveniently situated. The other plan meant is only as a suitable spot for drying and preparing the fur of sea lions and seals, and for extracting the spermaceti of the white or long-nosed whale, and the whale-bone and oil of the black species. Whales of every kind were seen sporting about Tristan d'Acunha, particularly near the setting of the sun; and the sword-fish likewise made its appearance occasionally.—Sir George Staunton's Account of the Embassy to China.