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hazardous experiment of crossing the Straits of Dover in »balloon ; they departed from Shakespeare ’s Cliff, and aftersome little difficulty, safely reached the opposite coast, anddescended in the forest of Guinnes. In 1793, the French Republic established an academy for aeronauts, at Meudon ,where a balloon was kept constantly filled and ready forexi>eriments. On the 26th June, 1794, Coutel, captain ofthe ..Eronautic Corps, ascended twice with the Entreprenantballoon, to the height of 4 SO yards, and conducted the impor-tant service of reconnoitering the hostile armies at the battleof Fleuras ; he was accompanied by a General and an Adju-tant, and by means of preconcerted signals, described theposition and manoeuvres of the enemy, and carried on a cor-resi>ondence with General Jourdan, the Commander of theFrench Army.

The parachute was invented by M. Gamerin, in 1802, tofacilitate the descent from the balloon in case of accident.

AIR-GUN. This machine, for expelling bullets by theexpansive force of air, is first noticed in the Elemens d’Artillerie , of David Rivant, the preceptor to Louis XIII. ; hegives the merit of the invention to Marin, a burgher ofLesieux, who presented one to Hen. IV. of France , aboutthe year 1592.

AIR-PUMP . Otto de Guericke , the celebrated Consul ofMagdeburgh, is the inventor of this instrument, and exhibitedhis first public experiment with it, before the Emperor andthe States of Germany , at the breaking up of the Imperial Diet at Ratisbon , in the year 1654. Boyle, however, withthe assistance of Dr. Hooke, very greatly improved upon theinvention, and hence, or rather from the great variety of expe-riments that illustrious author applied it to, he has by manybeen considered as the inventor; and the instrument itself,is frequently named after him the Boylian machine.