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100 Adye, Sir John Miller (1819–1900), British general and colonel commandant royal artillery, son of Major James P. Adye, royal artillery, was born at Sevenoaks, Kent, on the 1st of November 1819. He entered the royal artillery in 1836, was promoted captain in 1846, and served throughout the Crimean War of 1854-56 as brigade-major and assistant adjutant-general of artillery (medal with four clasps, Turkish medal, third class of the Legion of Honour, fourth class of the Medjidie, C.B., and brevets of major and lieut.-colonel). In the Indian Mutiny he served on the staff in a similar capacity (medal). Promoted brevet-colonel in 1860, he was specially employed in 1863 in the N.W. frontier of India campaign (medal with clasp), and was deputy adjutant-general, Bengal, from 1863 to 1866, when he returned home. From 1870 to 1875 Adye was director of artillery and stores at the War Office, where his influence was used to prevent the introduction of breech-loading ordnance. He was made a K.C.B. in 1873, having taken an active part in Mr Cardwell’s army reform. He was promoted to be major-general and appointed governor of the Royal Military Academy at Woolwich in 1875, and surveyor-general of the ordnance in 1880. In 1882 he was chief of the staff and second command of the expedition to Egypt, and served throughout the campaign (medal with clasp, bronze star, second class of the Medjidie, G.C.B., and thanks of Parliament). He held the government of Gibraltar from 1883 to 1886. Promoted lieut.-general in 1879, and general and colonel commandant of royal artillery in 1884, he retired in 1886. He unsuccessfully contested the Parliamentary representation of Bath in the Liberal interest in 1892. He died on 26th August 1900, when on a visit to Lord Armstrong in Northumberland. He was the author of A Review of the Crimean War; The Defence of Cawnpore; A Frontier Campaign in Afghanistan; Recollections of a Military Life; and Indian Frontier Policy.

Ægades, or, in Italian Egadi, a group of islands lying W. of Sicily and belonging to the prov. of Trapani, the largest being Marittimo, the ancient Hiera, rising to 2244 feet in Mount Falcone; Levanzo, the ancient Phorbantia, rising to 951 feet; and Favignana, the ancient Ægusa; altitude, 1070 feet; area of all, 70 square miles. Total population (1901), 6419. They carry on tunny and sponge fishing. Marittimo has a state prison, and produces honey and capers. Chief town and port, Favignana; cleared annually by some 400 vessels of about 100,000 tons. Population (1901), 5001.

Aeltre, a town of Belgium, in the province of East Flanders, 12 miles W. by N. of Ghent by rail, near the Ghent and Bruges canal. Its trade is mainly in linen and wood. Population (1900), 6261; communal (1880), 7020; (1897), 7174.

Aeronautics.—Notwithstanding the prejudice consequent on past failures and upon premature assertion of impending success, the advance in aeronautics since the publication of the ninth edition of this work has been greater and more rapid than at any time in history. This advance has consisted in :—(1) The evolution of light motors; (2) the elucidation of natural laws; (3) many partially successful experiments. Electric, steam, gas, or petroleum engines have been reduced to a fraction of their former weights, formerly-accepted data for computations have been quite superseded, and numerous experiments have been made.

Few scientific men have imitated Mr Glaisher in making high ascents for meteorological observations. Sivel, Crocé-Spinelli, and Tissandier, who reached 27,950 feet on 15th April 1875, were asphyxiated, and only Tissandier came down alive. This put a stop to such attempts for a time; but Gross and Berson attained 25,840 feet on 11th May 1894, Berson reached 29,740 feet on 4th December 1894, recording a temperature of –54° F., and Berson and Spencer are stated by the latter to have attained 27,500 feet on 15th September 1898, the thermometer registering –29° F. The personal danger attending such ascents led Hermite and Besançon to inaugurate in November 1892 the sending up of unmounted balloons (Ballons Sondes), equipped with automatic recording instruments (see ). On 11th July 1897, Andrée, Strindberg, and Fränkel ascended from Spitzbergen in a daring attempt to reach the North Pole by balloon. One carrier pigeon, apparently liberated forty-eight hours after the start, was shot, and two floating buoys with messages were found; but nothing more has been heard of the explorers.

From the very first invention of balloons the problem has been how to navigate them by propulsion. General Meusnier proposed an elongated balloon in 1784. It was experimented on by Robert Brothers, who made two ascensions and claimed to have obtained a deviation of 22° from the direction of a light wind by means of aerial oars worked by hand. The relative speed was probably about 3 miles an hour, and it was so evident that a very much more energetic light motor than any then known was required to stem ordinary winds that nothing more was attempted till 1852, when Giffard ascended with a steam-engine of then unprecedented lightness. The subjoined table exhibits the subsequent progress which has been made:—

Experiments with Dirigible Balloons.

Giffard, the future inventor of the injector, devised a steam-engine weighing, with fuel and water for one hour, 154 lb per horse-power, and was bold enough to employ it in proximity to a balloon inflated with coal gas. He was not able to stem a medium wind, but attained some deviation. He repeated the experiment in 1855 with a more elongated spindle, which proved unstable and dangerous. During the siege of Paris the Government decided to build a navigable balloon, and entrusted the work to the chief naval constructor, Dupuy de Lôme. He went into the subject very carefully, made estimates of all the strains, resistaneesresistances [sic], and speeds, and tested the balloon in 1872. Deviations of 12° were obtained from the course of a wind blowing 27 to 37 miles per hour. The screw propeller was driven by eight labourers, a steam-engine being deemed too dangerous; but it was estimated that had one been used, weighing as much as the men, the speed would have been doubled. Tissandier and his brother applied an electric motor, lighter than any previously built, to a spindle-shaped balloon, and went up twice in 1883 and 1884. On the latter occasion he stemmed a wind of 7 miles per hour. The brothers abandoned these experiments, which had been carried on at their own expense, when the French War Department took up the problem. Renard and Krebs, the officers in charge of the War Aeronautical Department at Meudon, built and experimented with in 1884 and 1885 the fusiform balloon “La France,” in which the “master” or maximum section was about one-quarter of the distance from the stem. The propelling screw was at the front of the car and driven by an electric motor of unprecedented lightness. Seven ascents were made on very calm days, a maximum speed of 14 miles an hour was obtained, and the balloon returned to its starting-point on five of the seven occasions. Since then another balloon has been constructed, said to be capable of a speed of 22 to 28 miles per hour, with a different motor; but no tests are known to the public and the secrets of this war engine