Part 5

ABSOLUTE Gravity, in philosophy, is the whole force by which a body, shell, or shot, is impelled towards the centre. See GRAVITY.

ABSOLUTE Number, in Algebra, is the known quantity which possesses entirely one side of the equation. Thus, in the equation, xx + 10x, = 64, the number 64, possessing entirely one side of the equation, is called the absolute number, and is equal to the square of the unknown root x, added to 10x, or to 10 times x.

ABUTMENT. See BRIDGES.

ACADEMY, in antiquity, the name of a villa situated about a mile from the city of Athens, where Plato and his followers assembled for conversing on philosophical subjects; and hence they acquired the name of Academics.

The term Academy is frequently used among the moderns for a society, of learned persons, instituted for the cultivation and improvement of arts or sciences. Some authors confound academy with university; but, though much the same in Latin, they are very different things in English. An university is, properly, a body composed of graduates in the several faculties; of professors, who teach in the public schools; of regents or tutors, and students who learn under them, and aspire likewise to degrees; whereas an academy was originally not intended for teaching, or to profess any art, but to improve it; it was not for novices to be instructed in, but for those who were more knowing; for persons of distinguished abilities to confer in, and communicate their lights and discoveries to each other, for their mutual benefit and improvement. The first academy we read of, was established by Charlemagne, by the advice of Alcuin: it was composed of the chief wits of the court, the emperor himself being a member.

Military ACADEMY. There are in England two royal military academies, one at Woolwich, and one at Portsmouth. The first was established by king George II. in 1741, endowed, and supported, for the instructing of the people belonging to the military branch of ordnance, in the several parts of mathematics necessary to qualify them for the service of the artillery, and the business of engineers. The lectures of the masters in theory were then duly attended by the practitioner-engineers, officers, serjeants, corporals, private men, and cadets. At present the gentlemen educated at this academy are the sons of the nobility and military officers. They are called gentlemen cadets, and are not admitted under 14 and not above 16 years of age. They are taught writing, arithmetic, algebra, Latin, French, mathematics, mechanics, surveying, levelling, and fortification, together with the attack and defence; gunnery, mining, laboratory works, geography, perspective, fencing, dancing, &c. The master-general of the ordnance is always captain of the company of gentlemen cadets, and some officer of merit is always captain-lieutenant. There is, besides, a first lieutenant, and two second lieutenants. They are further under the immediate care of a lieutenant-governor, and an inspector, who are officers of great abilities and experience; and the professors and masters are men of known talents and capacity. That at Portsmouth was founded by George I. in 1722, for teaching of the branches of the mathematics which more immediately relate to navigation.

For the American and French Military Academies, see SCHOOL.

ACANZI, in military history, the name of the Turkish light-horse that form the van-guard of the Grand Signior’s army on a march.

ACCELERATED Motion on oblique or inclined-planes. See MOTION.

ACCELERATED Motion of pendulums. See PENDULUMS.

ACCELERATED Motion of Projectiles. See PROJECTILES.

ACCENDONES, in military antiquity, a kind of gladiators, or supernumeraries, whose office was to excite and animate the combatants during the engagement.

ACCENSI, in antiquity, were officers attending the Roman magistrates; their business was to summon the people to the public games, and to assist the prætor when he sat on the bench.

Accensi, in military antiquity, was also an appellation given to a kind of adjutants appointed by the tribune to assist each centurion and decurion. According to Festus, they were supernumerary soldiers, whose duty it was to attend their leaders, and supply the places of those who were either killed or wounded. Livy mentions them as irregular troops, but little esteemed. Salmasius says, they were taken out of the fifth class of the poor citizens of Rome.

ACCESSIBLE, that which may be approached. We say, in a military stile, that place, or that fortress, is accessible from the sea, or land, i. e. it may be entered on those sides.

An accessible height or distance, in geometry, is that which may be measured by applying a rule, &c. to it: or rather, it is a height, the foot whereof may be approached, and from whence any distance may be measured on the ground.

Heights, both accessible, and inaccessible, may be taken with a quadrant. See ALTITUDE; and the article on Field Fortifications in the American Military Library, Theorem 11, 12, 13, 14, 15.

One of the objects of surveying, is the measuring both accessible and inaccessible distances.

ACCLIVITY, in a military sense, is the steepness or slope of any work, inclined to the horizon, reckoned upwards. Some writers on fortification use acclivity as synonymous with talus; though talus is commonly used to denote all manner of slopes, either in its ascendent or descendent state.

ACCONTIUM, in ancient military writers, a kind of Grecian dart or javelin, somewhat resembling the Roman pilum.

ACCOUTREMENTS, in a military sense, signify habits, equipage, or furniture, of a soldier, such as belts, pouches, cartridge-boxes, saddles, bridles, &c. Accoutrements should be made of stout leather, not of the spongy kind, which is always stretching, and difficult to clean. The belts are about 2¹⁄₄ inches broad, with two buckles to fix them to the pouch. Pouches are made of the stoutest blackened leather, especially the outside flaps, which are of such a substance as to turn the severest rain. Cartridge-boxes are made as light as possible, with holes in each, to hold cartridges. See CARTRIDGE.

ACLIDES, in Roman antiquity, a kind of missive weapon, with a thong fixed to it, whereby it might be drawn back again. Most authors describe the aclides as a sort of dart or javelin: but Scaliger makes it roundish or globular, with a wooden stem to poise it by.

ACOLUTHI, in military antiquity, was a title in the Grecian empire, given to the captain or commander of the varangi, or body-guards, appointed for the security of the emperor’s palace.

ACTIAN games in antiquity, were games instituted, or at least restored, by Augustus, in memory of the famous victory, at Actium, over Mark Antony.

ACTIAN years, in chronology, a series of years, commencing with the epocha of the battle of Actium, otherwise called the æra of Augustus.

ACTION, in the military art, is an engagement between two armies, or any smaller body of troops, or between different bodies belonging thereto. The word is likewise used to signify some memorable act done by an officer, soldier, detachment or party.

ACTIVITY, in a military sense, denotes laboriousness, attention, labor, diligence and study.

ACUTE angle. See ANGLE.