surface of common clouds, and there remaining and visible at rest; while some, moving slowly in various directions, completed a view truly majestic,

As we cannot give a detail of all the ærial voyages made in this and other countries, we shall only mention those of Mr. Garnerin, in one of which he ascended at Ranelagh, near London, and descended at Colchester, a distance of 60 miles in about 3 quarters of an hour. This was in June 1802: but in September, he ascended from North Audleystreet, London, in order to shew that he could come down in safety, by means of a parachute: which he did, in a field near St. Pancras church. The balloon used on this occasion, was of the common sort, viz. of oiled silk, with a net, from which ropes proceeded that terminated in or were joined to a single rope, at a few feet below the balloon. To this rope the parachute was fastened. The parachute was a large umbrella, about 30 feet in diameter, but destitute of ribs or handle. Several ropes about 30 feet in length, proceeded from the edge of the parachute terminating in a common joining, from this, shorter ropes were fixed, to the extremities of which a circular basket was fastened. In this Mr. Garnerin placed himself, and when every thing was steady, he cut the rope, and in an instant was separated from the balloon, trusting his safety to the parachute. For a few seconds, before the parachute opened, he fell with` very great velocity, but as soon as that expanded the descent became gradual. On coming to the earth, Mr. Garnerin experienced some pretty severe shocks, but without receiving any material injury. Fig. 4. represents a balloon in its ascent: and fig. 5. Garnerin as coming down by means of the parachute.

As hydrostatics is the science of the weight of water, so aerostatics is that of the weight of air : air and water are both fluids: and a balloon rises into the one, upon the same principle that a vessel floats upon the other. Air is lighter than water; and, therefore, a body, containing a quantity of air greater in bulk than the water it displaces, will swim; and rarefied or inflammable air being lighter than the common atmosphere, a body containing either the rarefied or inflammable air will ascend till its nature is altered, or it arrives in a fluid as light as itself, and consequently has gained the surface of the heavy atmosphere. The most familiar exposition of this principle that can be offered, may be seen in those air-bubbles which, on pouring water rapidly into a glass, arise, with the utmost velocity, from the bottom to the surface, and there, becoming stationary, form a temporary froth. The water represents the air, and the air-bubble the balloon. See more onthis subject under the article PNEUMATICS.

ETHER, or Ether, a thin, subtle, and perfectly pure fluid. The term is used by natural philosophers ancient and modern; but the thing or matter meant is variously described. According to electricians, it is the electric fluid, or solar light. It may be understood to be a fluid that fills all space; in which the stars revolve; and which, when impregnated with earthy exhalations, forms the air or atmosphere. In this sense, ether is what is called rarefied air: that is, ether disburdened of intermingling particles. See Air.

ETNA. A volcano or burning mountain of Sicily, situated in lat. 38. N. long. 154. E.-This mountain, famous from the remotest antiquity both for

its bulk and terrible eruptions, stands in the eastern part of the island, in a very extensive plain, called Val Demoni, from the notion of its being inhabited by devils, who torment the spirits of the damned in the bowels of this volcano. Authors are not agreed as to its dimensions, or its height above the surface of the sea. The accounts given of the phænomena which have accompanied its eruptions, by sir William Hamilton and Mr. Brydone, are exceedingly interesting. According to the observations of the last mentioned traveller, the height of Ætna is about 12,000 feet. Faujas de S. Fond states it at 10,036 feet. The circumference of the base is commonly reckoned about 180 miles. There are 77 cities, towns, and villages, scattered over different parts of the sides of this mountain, and the number of its human inhabitants above is 100,000. The distance from Catania to the summit exceeds 30 miles. The fire which is continually burning in the bowels of this mountain, led the poets to place here the forges of the cyclops, under the direction of Vulcan, and the prison of the giants who rebelled against Jupiter. The eruptions of this mountain have likewise been described by several of the ancient poets.

AFFINITY, in natural philosophy, 1. The tendency which the particles of matter have to be attracted or united to each other. 2. Elective attraction simple, reciprocal, or double. 3. Sympathy or consent of parts. The power by which one organ is affected by another, whether directly or inversely.

AFRICA, one of the quarters of the globe: commencing, northward, at the opposite coast of the strait of Gibraltar; extending along the whole

western side of the Mediterranean Sea; divided from Asia by the Red; extending into the Indian; and forming the eastern boundary of the Atlantic, from the Cape of Good Hope, to the strait whence its limits have been traced. The principal rivers of Africa are the Niger, the Senegal, the Gambia, the Laira, the Coanza and the Nile: the principal mountains are the Atlas, the Mountains of the Moon, and the Sierra Leona. Africa produces lions, leopards, tigers, panthers, rhinoceroses, elephants, cameleons, ostriches, camels, monkeys, &c. and in the rivers there are crocodiles and river-horses.

AFRICAN COMPANY, a society of merchants established by Charles II. for trading to Africa. This commerce is now laid open to all the subjects of the realm, paying 10 per cent. for the maintenance of the forts.

AFTERSWATH, or Aftersward, in husbandry, the grass which grows up after mowing: it is called in some counties ROWEN.

AGA, in the Mogul language, a great lord or commander; in the Turkish, it is applied in courtesy, to a gentleman or wealthy landholder;

or on

account of post or rank, as to the commander in chief of the janissaries. The title Aga is known in other Mahometan countries. The chief officers under the khan of Tartary are called by this name; and among the Algerines we read of agas chosen from among the boluk bashi (the first rank of military officers) and sent as governors in chief of towns and garrisons. The aga of Algiers is the president of the divan or senate.

AGATE, a precious stone, which naturalists have ranked among the semi-transparent precious

stones. Agates are distinguished, with reference to their degrees of transparency, into two kinds, and called oriental and occidental: the first generally comes from the eastern parts of the world, as its name implies; and the second is found in the western, as Germany, Bohemia, and other countries. The oriental agate is known by its clearness, transparency, and the beautiful polish of which it is susceptible: the occidental, on the other hand, is obscure, its transparency cloudy, and its polish much inferior to that of the former. All agates from the east have not, however, the perfections for which this class are celebrated; and some occidental are occasionally found that may be compared to the oriental without disadvantage. It is more difficult to distinguish the agate from other demitransparent stones, such as the chalcedonix and the sardonix, than to recognize it among stones entirely opaque. Owing to this variety, and this affinity to other stones, which are its characteristics, the agate has been divided into several kinds. The agate, simply so called, is of one colour, or more, clouding, like the veins in marble, into irregular forms, placed without order, and confounded with one another. The tints and shades of these colours vary almost to infinity, and, in their mixture, present curious, and sometimes very singular, shapes. Banks, rivulets, and trees, and often animals and human figures, are to be distinguished; and, with a little assistance from the imagination, complete pictures are perceived.

AGE, signifies 1. Any period of time attributed to something, as the whole, or part of its duration. 2 A succession or generation of men. 3. The