in the exhausted receiver, heavy and light bodies fall equally swift; so, a guinea and feather fall from the top of a tail receiver to the bottom exactly together. That most animals die in a minute or two: but, however, that vipers and frogs, though they swell much, live an hour or two; and after being seemingly quite dead, come to life again in the open air: that snails survive about ten hours; efts, or slowworms, two or three days; and leeches five or six. That oysters live for 24 hours. That the heart of an eel taken out of the body continues to beat for good part of an hour, and that more briskly than in the air. That warm blood, milk, gall, &c. undergo a considerable intumescence and ebullition. That a mouse or other animal may be brought, by degrees, to survive longer in a rarefied air, than naturally it does. That air may retain its usual pressure, after it is become unfit for respiration. That the eggs of silk-worms hatch in vacuo. That vegetation stops. That fire extinguishes; the flame of a candle usually going out in one minute; and a charcoal in about five minutes. That red-hot iron, however, seems not to be affected; and yet sulphur or gunpowder are not lighted by it, but only fused. That a match, after lying seemingly extinct a long time, revives again on readmitting the air. That a flint and steel strike sparks of fire as copiously, and in all directions, as in air. That magnets, and magnetic needles, act the same as in air. That the smoke of an extinguished luminary gradually settles to the bottom in a darkish body, leaving the upper part of the receiver clear and transparent; and that on inclining the vessel sometimes to one side, and sometimes to another, the fume preserves its surface horizontal, after the nature of other fluids. That heat may be produced by attrition. That camphire will not take fire; and that gunpowder, though some of the grains of a heap of it be kindled by a burning glass, will not give fire to the contiguous grains. That glow-worms lose their light in proportion as the air is exhausted, and at length become totally obscure; but on readmitting the air, they presently recover it all. That a bell, on being struck, is not heard to ring, or very faintly. That water freezes. But that a syphon will not run. That electricity appears like the aurora borealis. With multitudes of other curious and important particulars, to be met with in the numerous writings on this machine, namely, besides the Philos. Transactions of most academies and societies, in the writings of Torricelli, Pascal, Mersenne, Guericke, Schottus, Boyle, Hook, Duhamel, Mariotte, Hawksbee, Hales, Muschenbroeck, Gravesande, Desaguliers, Franklin, Cotes, Helsham, Martin, Ferguson, Adams, Nicholson, Cavallo, Gregory, Hutton, &c.

AIR-SHAFTS, among miners, denote holes or shafts let down from the open air to meet the adits, and furnish fresh air. The damps, want and impurity of air, which occur, when adits are wrought 30 or 40 fathoms long, make

it necessary to let down air-shafts, in order to give the air liberty to play through the whole work, and thus discharge bad vapours, and furnish good air for respiration: the expence of which shafts, in regard of their vast depths, hardness of the rock, drawing of water, &c. sometimes equals, nay exceeds, the ordinary charge of the whole adit.

AIR-VESSEL, in hydraulics, is a name given to those metalline cylinders, which are placed between the two forcing-pumps in the improved fire-engines. The water is injected by the action of the pistons through two pipes, with valves, into this vessel; the air previously contained in it will be compressed by the water, in proportion to the quantity admitted, and by its spring force the water into a pipe, which will discharge a constant and equal stream; whereas in the common squirting en gine, the stream is discontinued between the several strokes.

AIR-VESSELS, in botany, are certain canals, or ducts, by which a kind of absorption and respiration is effected in vegetables. Air-vessels are distinguished from sap-vessels; the former being supposed to correspond to the trachea and lungs of animal; the latter to their lacteals and blood-vessels. Air-vessels are found not only in the trunks or stems, but also in the leaves of all plants, and are easily discoverable in many without the help of glasses; for upon breaking the stalk or chief fibres of a leaf the likeness of a fine woolly substance, or rather of curious small cobwebs, may be seen to hang at both the broken ends; and this is really a skein of air-vessels. See Grew's Anat. of Roots, ch. iv. p. 155, &c. See also Darwin's Phytologia, where the air-vessels and the absorbents of plants are very ingeniously distinguished.

AIRY. a. (from air, aëreus, Lat.) 1. Composed of air (Bacon). 2. Relating to the air (Boyle). 3. High in air (Addison). 4. Open to the free air (Spenser). 5. Light as air; unsubstantial (Shakspeare). 6. Without reality; vain; trifling (Temple). 7. Fluttering; loose; full of levity (Dryden). 8. Gay; sprightly; full of mirth; vivacious; lively; light of heart (Taylor).

AIRY TRIPLICITY, in astrology, the signs Gemini, Libra, and Aquarius.

AISE, a river of France, which runs into the Orne, three leagues above Caen.

AISLE. s. The walk in a church (Addis.). AISNE, in geography, a river of France, which rises in Champagne, runs by Soissons, and falls into the Oise above Compiegne. It gives name to a department which is one of six formed of the ci-devant Soissonnois, le Beavoisis, and le Vexin Francois; and is one of the five into which the ancient Isle of France is divided.

A'ISTHESIS. (aloficis, from alctavojai, la perceive.) A sense; either external, as the sight, touch, &c. or internal, as the memory. judgment, &c.

AISTHETERIUM, aidsTypior, from

man, to perceive.) The sensory, or seat and origin of sensation. See SENSORIUM COM

MUNE.

AIT. . A small island in a river.

AITONA, in geography, a small town of Spain in Catalonia, the capital of a marquisate. AITONIA. In botany, a genus of the class and order monadelphia octandria, so named in honour of Mr. Aiton, the royal and truly-scientific gardener at Kew. It is thus characterised, calyx four-parted; petals four; style one; berry dry, quadrangular, one-celled, many-seeded. The only known species is a cape-shrub with flesh-colour flowers.

AJUGA. Bugle; ground pine. A genus of the class and order didynamia gymnospermia. Is corol with the upper lip very minute and emarginate; stamens longer than the upper lip. It includes ten species found in different parts of Europe and Asia: of which two are common to our own woods and fields. The a. reptans (creeping bugle) found in the former, and the a chamæpitys (common ground pine) frequent in the latter. The a. pyramidalis, a native of Denmark, and other parts of Europe, is still employed in medicine, and constitutes the consolida media of the pharmacopoeias, which see.

AIUS LOCUTIUS, a deity to whom the Remans erected an altar, because under that e a supernatural voice had given_warning the attack about to be made on Rome by the Gauls, in the time of Camillus.

AJUTAGE, or ADJUTAGE, in hydraulics, part of the apparatus of a jet d'eau, or artificial fountain; being a kind of tube fitted to the aperture or mouth of the cistern, or the pipe; through which the water is to be played in any direction, and in any shape or figure.

It is chiefly the diversity in the ajutage, that makes the different kinds of fountains. So that, by having several ajutages, to be applied occasionally, one fountain is made to have the effect of many.

Mariotte, Gravesande, and Desaguliers have written pretty fully on the nature of ajutages, or spouts for jets d'eau, and especially the former. He affirms, from experiment, that an even polished round hole, made in the thin end of a pipe, gives a higher jet than either a cylindrical or a conical ajutage; but that, of these two latter however, the conical is better than the cylindrical figure.

The quantity of water discharged by ajutages of equal area, but of different figures, is the same. And for like figures, but of different sizes, the quantity discharged is directly proportional to the area of the ajutage, or to the square of its diameter, or of any side or other linear dimension: so, an ajutage of a double diameter, or side, will discharge 4 times the quantity of water; of a triple diameter, 9 times the quantity; and so on; supposing them at an equal depth below the surface or head of water. But if the ajutage be at different depths below the head, then the celerity with which the water issues, and consequently the quantity of it run out in any given time, is di

rectly proportional to the square-root of the altitude of the head, or depth of the hole: so at 4 times the depth the celerity and quantity is double; at 9 times the depth, triple; and so on.

It has been found that jets do not rise quite so high as the head of water; owing chiefly to the resistance of the air against it, and the pressure of the upper parts of the jet upon the lower: and for this reason.it is, that if the direction of the ajutage be turned a very little from the perpendicular, it is found to spout rather higher than when the jet is exactly upright.

It is found by experiment too, that the jet is higher or lower, according to the size of the ajutage: that a circular hole of about an inch and a quarter in diameter, jets highest; and that the farther from that size, the worse. Experience also shews that the pipe leading to the ajutage should be much larger than it; and if the pipe be a long one, that it should be wider the farther it is from the ajutage. Hutton's Dictionary.

For the experiments of Bossut on this interesting subject, see Gregory's Mechanics, book iv. ch. 2.

AIX, a small island on the coast of France. Lat. 46. 5 N. Lon. 1. 5 W.

Aix, an ancient city of Provence, in France. Lat. 43. 32 N. Lon. 5. 32 E.

AIX LA CHAPELLE, a fine city of Westphalia, in Germany. It is famous for several councils and treaties of peace concluded here, particularly those between France and England in 1748. It is 26 miles almost E. from Liege, and 40 almost W. from Cologne. Lat. 50. 50 N. Lon. 5. 48 E.

AIX LA CHAPELLE. A town in the south of France, renowned in medicine and chemistry for its sulphureous water, the most striking feature of which, and what is almost peculiar to it, is the unusual quantity of sulphur it contains; the whole, however, is so far united to a gaseous basis, as to be entirely volatilized by heat: so that none is left in the residuum after evaporation. This thermal water is much resorted to on the continent, for a variety of complaints. It is found essentially serviceable in the numerous symptoms of disorders in the stomach and biliary organs, that follow a life of high indulgence in the luxuries of the table; in nephritic cases; stiffness and rigidity of the joints and ligaments, from rheumatism and gout; in palsy, and in the distressing debility which follows a long course of mercury and excessive salivation.

A'IZOON. In botany, a genus of the class and order icosandria pentagynia. Calyx fiveparted; petalless; capsule superior, five-celled, five-valved. There are ten species, the greater number of which are indigenous to the Cape. Spain owns one and the Canaries one; the a Canariense and the a. Hispanicum.

AIZO'UM. (awov, from au, always, and ww, to live.) An ever-green aquatic plant, like the aloe.

To AKE. v. n. from ¿x, Gr.) To feel a lasting pain (Locke).