Homer, was, next to Hector, the bravest of the warriors of Troy. When that
town was taken and set on fire, Aeneas, according to the narrative of
Virgil, with his father, son, and wife Creusa, fled, but the latter was
lost in the confusion of the flight. Having collected a fleet he sailed for
Italy, but after numerous adventures he was driven by a tempest to the
coast of Africa, where Queen Dido of Carthage received him kindly, and
would have married him. Jupiter, however, sent Mercury to Aeneas, and
commanded him to sail to Italy. Whilst the deserted Dido ended her life on
the funeral pile, Aeneas set sail with his companions, and after further
adventures by land and sea reached the country of King Latinus, in Italy.
The king's daughter Lavinia was destined by an oracle to wed a stranger,
this stranger being Aeneas, but was promised by her mother to Turnus, King
of the R[)u]t[)u]li. This occasioned a war, which was ended by Aeneas
slaying Turnus and marrying Lavinia. His son by Lavinia, Aeneas Sylvius,
was the ancestor of the kings of Alba Longa, and of Romulus and Remus, the
founders of the city of Rome.
AEOLIAN HARP, or AEOLUS' HARP, a musical instrument, generally consisting
of a box of thin fibrous wood (often of deal), to which are attached from
eight to fifteen fine catgut strings or wires, stretched on low bridges at
either end, and tuned in unison. Its length is made to correspond with the
size of the window or other aperture in which it is intended to be placed.
When the wind blows athwart the strings it produces very beautiful sounds,
sweetly mingling all the harmonic tones, and swelling or diminishing
according to the strength or weakness of the blast.
AEOLIANS (Gr. _Aioleis_), one of the four races into which the ancient
Greeks were divided, originally inhabiting the district of AE[)o]lis, in
Thessaly, from which they spread over other parts of Greece. In early times
they were the most numerous and powerful of the Hellenic races, chiefly
inhabiting Northern Greece and the western side of Peloponnesus, though
latterly a portion of them went to Lesbos and Tenedos and the north-west
shores of Asia Minor, where they possessed a number of cities. Their
language, the Aeolian dialect, was one of the three principal dialects of
the Greek. It was cultivated for literary purposes chiefly at Lesbos, and
was the dialect in which Alcaeus and Sappho wrote.
AEOL'IPILE (Lat. _AE[)o]li pila_, the ball of AE[)o]lus), a spherical
vessel of metal, with a pipe of small aperture, through which the vapour of
heated water in the ball passes out with considerable noise; or having two
nozzles so placed that the steam rushing out causes it to revolve on the
principle of the Barker's mill. It was known to the ancient Greeks.
AE'OLUS, in Greek mythology, the god of the winds, which he kept confined
in a cave in the Aeolian Islands, releasing them when he wished or was
commanded by the superior gods.
AE'ON, a Greek word signifying life, an age, and sometimes eternity, but
used by the Gnostics to express spirits or powers that had emanated from
the Supreme Mind before the beginning of time. They held both Christ and
the Holy Spirit to be aeons; but as they denied the divine origin of the
books of Moses, they said that the spirit which had inspired him and the
prophets was not that exalted aeon whom God sent forth after the ascension
of Christ, but an aeon very much inferior, and removed at a great distance
from the Supreme Being.
AEPYOR'NIS, a genus of gigantic birds whose remains have been found in
Madagascar, where they are supposed to have lived perhaps not longer than
200 years ago. It had three toes, and is classed with the cursorial birds
(ostrich, &c.). Its eggs measured 14 inches in length, being about six
times the bulk of those of the ostrich. The bird which laid them may well
have been the roc of Eastern tradition.
AE'QUI, an ancient people of Italy, conspicuous in the early wars of Rome,
and inhabiting the mountain district between the upper valley of the Anio
(Teverone) and Lake Fuc[)i]nus. They were probably akin to the Volscians,
with whom they were in constant alliance. They were defeated by Cincinnatus
in 458 B.C., and again by the dictator Postumius Tubertus in 428 B.C., and
were finally subdued about 304-302 B.C. Soon after they were admitted to
Roman citizenship.
A'ERATED BREAD, bread which receives its sponginess or porosity from
carbonic acid supplied artificially, and not produced by the fermentation
caused by leaven or yeast.
A'ERATED WATERS, waters impregnated with carbonic acid gas, and forming
effervescing beverages. Some mineral waters are naturally aerated, as
Vichy, Apollinaris, Rosbach, &c.; others, especially such as are used for
medicinal purposes, are frequently aerated to render them more palatable
and exhilarating. Water simply aerated, as soda-water, or aerated and
flavoured with lemon or fruit syrups, is largely used, especially in
summer, as a refreshing beverage. There are numerous varieties of apparatus
for manufacturing aerated waters. The essential parts of an aerated-water
machine are a generator in which the gas is produced, a vessel containing
the water to be impregnated, and an apparatus for forcing the gas into the
water. This last may be effected by force-pumps or by the high pressure of
the impregnating gas itself. The quantity of gas with which the water is
charged is usually equal to a pressure of 5 atmospheres. See also _Mineral
Waters_.--Cf. W. Kirkby, _Evolution of Artificial Mineral Waters_.
AERIAL ROPEWAYS or CABLEWAYS, a means of transport or carriage in which a
great rope or cable, elevated above the ground on fixed supports, is made
use of in conveying from place to place materials or articles of various
kinds. Such a cable may be said to serve the purpose of a rail, from which
are suspended the carriages, buckets, or carriers of whatever sort are
employed to convey the materials dealt with, the cable being actuated by
means of a steam-engine and winding-gear of suitable construction. Such
cables are now much used in carrying materials over a comparatively short
space, as in quarries, excavations for canals, docks, &c.; in the
construction of bridges, in shipbuilding, &c. Besides being employed in
such works--not to mention the coaling of a battleship at sea from a coal
transport standing by--elevated ropeways miles in length have also been
constructed between places where no roads exist, or where road carriage is
much more expensive. The greatest aerial line yet in existence is in the
Argentine Republic, being built to connect a mining locality in the Andes,
about 15,000 feet above sea-level, with a station on the Northern Railway
11,500 feet lower down and about 22 miles off, the line running across deep
chasms and hollows, and being in places supported on iron towers 130 feet
high. The wire rope is said to have a length of 87 miles.
AE'RIANS, the followers of Aerius of Pontus, who in the fourth century
originated a small heretical sect, objecting to the established feast-days,
fasts or abstinences, the distinction between bishops and presbyters,
prayers for the dead, &c.
AERODYNAM'ICS, a branch of physical science which treats of the properties
and motions of elastic fluids (air, gases), and of the appliances by which
these are exemplified. This subject is often explained in connection with
hydrodynamics. See also _Meteorology_.
AEROE, or ARROE ([:a]r'eu-e), an island of Denmark, in the Little Belt, 15
miles long by 5 broad, with 12,000 inhabitants. Though hilly, it is very
fertile.
A'EROLITE, a meteoric stone, meteorite, or shooting-star. See _Meteoric
Stones_.
[Illustration: "Montgolfiere", or Hot-air Balloon, above Furnace]
AERONAU'TICS, the art or science of navigating the air, including Aviation
(see _Aeroplane_ and _Sea-planes_) and Aerostation (see _Balloons_ and
_Air-ships_). From the days of the mythical exploit of Daedalus and Icarus,
students of 'experimental philosophy', or scientists, of all ages, turned
their thoughts and inventive genius to the evolution of a machine by means
of which man could fly. Most of the early schemes of which any details have
survived were based upon the observation of birds and embodied the flapping
of wings affixed to the arms or legs. Among the very early experimenters
may be mentioned the monk Oliver of Malmesbury (A.D. 1050), de Perouse
(1420), who is said to have succeeded in flying over Lake Trasimene, and
the great Leonardo da Vinci. All these produced designs for what are known
as Ornithopters, or flapping-wing machines. There was, however, another
school which believed in the future of machines which would be themselves
lighter than air. The idea in the minds of the experimenters of this school
was in the early days the replacing of the air in brass globes by a vacuum.
If the brass were thin enough it was believed that the globe would then be
sufficiently light to rise. It was, however, not realized that under such
circumstances the globe would inevitably collapse under the pressure of the
atmosphere with no corresponding internal pressure to withstand it. Among
this 'lighter-than-air' school of experimenters were the famous Roger Bacon
(twelfth century), Robert Hooke of the Royal Society (1644), and Francesco
de Lana, a Jesuit priest (1660). It was this school which ultimately
achieved success by providing the first machine of any sort to leave the
ground and rise into the air. On 5th June, 1783, the first balloon ascended
from the village of Annonay in France. It owed its inception to the genius
of two brothers, paper-makers by trade, named Etienne and Joseph
Montgolfier. Struck by the sight of smoke ascending from a chimney, after
many failures with flapping-wing models, they conceived the idea of filling
a receptacle with smoke and seeing if it would rise. They built a balloon
or 'globe' of paper and canvas, and lit a fire of wood and straw below the
aperture in it. The balloon gradually filled and rose into the air to a
height reported to be 6000 feet, though this is probably an exaggeration.
It remained in the air for ten minutes and landed 1-1/2 miles away. This
was the forerunner of the 'Montgolfieres', or hot-air balloons, which are a
feature of fetes and Guy Fawkes' Day celebrations. It was followed by the
sending up of a 'Montgolfiere' from Versailles on 18th Sept. of the same
year, carrying a basket containing a sheep, a cock, and a duck. The first
human beings to make an ascent were Pilatre de Rozier and the Marquis
d'Arlande, who went away from Paris on 21st Nov., 1783. They passed right
over Paris, and were in the air for twenty-five minutes, during which time
they replenished the fire suspended in a brazier below the neck of the
balloon.
The real genesis of the balloon, or air-ship as we know it to-day, was due
to the discovery of hydrogen as the lightest gas, which discovery was made
in 1766 by an English chemist, Henry Cavendish. Various people claim the
credit of having been the first to call attention to the possibilities of
this gas for aerial navigation. In 1781 Dr. Joseph Black of Edinburgh
suggested to his pupils that a thin bladder filled with 'the inflammable
gas' (hydrogen) would rise into the air, but it appears doubtful whether he
ever actually made the experiment. Tiberius Cavallo the same year, before
the Royal Society, demonstrated that soap-bubbles filled with hydrogen
would rise and float in the air. The honour of building the first hydrogen
balloon belongs, however, to three Frenchmen--the brothers Robert, and
Charles, a physicist. They sent up a hydrogen-filled balloon of varnished
silk from the Champ de Mars, Paris, on 7th Aug., 1783. One of the Roberts
and Charles themselves made the second human ascent in their balloon--the
first in a hydrogen balloon as opposed to a Montgolfiere (as above)--on 1st
Dec. the same year. In 1784 the same Frenchmen constructed the first
'air-ship' or navigable balloon to the order of the Duc de Chartres
(Philippe Egalite). The gas container of this was elongated in form, and it
could be propelled to some small extent by means of oars, and steered by a
rudder. In the same year a French military officer, named Meusnier,
produced a completely detailed design for an air-ship. This embodied the
first suggestion of screw-propellers, to be worked by man-power, and also
provided for a 'ballonet' into which air could be driven to replace
hydrogen lost owing to expansion during the ascent. Meusnier's design was
the genesis of the modern non-rigid air-ship, all the essential features
remaining. This air-ship was, however, never built.
[Illustration: Giffard's Steam-driven Air-ship]
The first ascent in the British Isles was made in a Montgolfiere by James
Tytler at Edinburgh, on 27th Aug., 1784, though he travelled only a few
hundred yards. He was followed by Vincent Lunardi, an Italian, who ascended
from the artillery ground in London three weeks later (Sept., 1784),
landing near Ware in Hertfordshire. The first Channel crossing by air was
made in a hydrogen balloon from Dover to Calais on 7th Jan., 1785, by
Blanchard and Dr. Jeffries.
Subsequent developments in air-ships are due to the pioneer work of Giffard
(1852) (the first steam-driven air-ship), Dupuy de Lome (1872), the
brothers Tissandier (electric propulsion) (1883), Renard and Krebbs (1884),
Woelfert (1897), Santos Dumont (1898-1905), Zeppelin (1900), Lebaudy
(1903), Barton (English) (1905), Willows (English) (1910).
In the meantime experimental work was being carried on by the exponents of
the heavier-than-air school, who soon abandoned the flapping-wing principle
and eventually evolved the modern aeroplane. The modern aeroplane was
evolved from the brain of an Englishman, Sir George Cayley, who in 1809
contributed an article to _Nicholson's Journal_ in which he outlined the
outstretched wings, vertical and horizontal steering surfaces,
screw-propeller, 'explosion' motor, and 'stream-line' form of the modern
aeroplane. In 1842 Henson and Stringfellow, both Englishmen, constructed a
steam-driven model on this principle, which is now in the South Kensington
Museum. Wenham in 1866 contributed a valuable paper to the Royal
Aeronautical Society on the subject. In 1896 Lillienthal in Germany carried
out a number of glides with rigid wings, provided with a movable tail,
fixed to his body. He was followed by Chanute, who in America emphasized
the biplane principle in his glider. In 1896 Ader, a Frenchman, built an
'avion' which is claimed to have risen from the ground at Satory, but this
is doubtful. In 1895 a huge steam-propelled aeroplane built by Sir Hiram
Maxim burst the rails holding it down and lifted for a few feet.
[Illustration: A Handley Page Biplane, showing the principal parts]
[Illustration: Wright's Biplane Glider]
The real credit for the evolution of a man-carrying aeroplane is, however,
due to the American brothers Wilbur and Orville Wright of Dayton, Ohio.
Encouraged by the advice of Chanute, they commenced experimenting with
biplane gliders on the sand-hills at Kittyhawk. Meeting with considerable
success, they fitted a petrol motor of their own design in 1903 and made
several straight flights during the same year. In 1904 they succeeded in
making the first turn in the air. These experiments were carried out in
great secrecy, and it was not until 1908 that their first public flights
were made in France, the first taking place in October of that year. The
first aviator to fly in Europe was Santos Dumont, who, on 12th Nov., 1906,
covered 220 metres, having previously in the same year flown for shorter
distances. At this time and during the two or three ensuing years many
experiments were carried out, and flights made, by Farman, Voisin,
Esnault-Pelterie, and Bleriot in France; Wright and Curtiss in America; and
Roe, Ogilvie, and Moore-Brabazon in England. A prize of L2000 offered by
MM. Deutsch de la Meurthe and Ernest Archdeacon for the first circular
flight over a distance of 1 kilometre, returning to the point of starting,
was won in Jan., 1908, by Henry Farman.
The second crossing of the Channel, and the first by a 'heavier-than-air'
machine, was effected by Louis Bleriot in a machine of his own construction
with an Anzani engine from Calais to Dover on 25th July, 1909. From that
date the science of aviation (flight by heavier-than-air machines) may be
said to have begun, and progress was merely a record of improvements. By
the end of 1919 the Atlantic had been crossed four times; once by
sea-plane, once by a non-stop aeroplane flight, and twice (outward and
return) by non-stop air-ship flights. Aeroplanes had achieved a speed of
190 miles an hour, had attained to a height of over 34,000 feet, and had
covered upwards of 1900 miles in one non-stop flight.--BIBLIOGRAPHY: De St.
Fond, _Description de la Machine Aerostatique_; Cavallo, _History and
Practice of Aerostation_; Lunardi, _The First Aerial Voyage in England_;
Moedebeck, _Pocket Book of Aeronautics_; Santos Dumont, _My Air-ships_;
_The Aeronautical Classics_ (Aeronautical Society); G. Tissandier,
_Histoire des Ballons_; A. Berget, _The Conquest of the Air_.
[Illustration: Early Types of Aeroplanes
(a) Wright Biplane (1908). (b) Bleriot Monoplane (1909).
(c) Santos Dumont Biplane (1906).]
AEROPLANE, a flying-machine deriving its power of sustentation from the
reaction of the air driven downwards by the rapid transit of fixed wings or
'planes' through the air. The term 'plane' for the wing of an aeroplane is
strictly a misnomer, as the word implies a flat plate, whereas a wing is
'cambered' or curved in section from front to back. This is due to the
discovery of Lillienthal (see _Aeronautics_) that a cambered 'aerofoil'
when set at an angle to a wind current gives more 'lift' than a flat plane.
The wing of an aeroplane is normally set at an angle horizontally (or
rather at an angle to the relative wind) varying from 0deg to 4deg. This
angle is known as the 'angle of incidence'. As the wing is driven through
the air under the influence of the propeller, the air meets the 'leading'
or 'entering' edge and is divided into two streams along the top and bottom
surfaces. It does not, however, follow the surface closely, but in the case
of the lower stratum is deflected downwards at an angle to the surface,
which results in an upward reaction. The upper of the two streams of air is
correspondingly deflected upwards at an angle to the surface for a short
distance. This causes an 'area of discontinuity of flow', or eddy, which
results in 'negative pressure', causing an upward suction. This fact was
first discovered by Sir Hiram Maxim, though it was G. Eiffel who measured
the effects of the positive pressure on the lower surface and the negative
pressure on the upper surface, and found, contrary to all expectation, that
the latter is responsible for three-quarters of the total lifting effect of
the wing. In addition to the lift, the wings offer resistance to progress
through the air, which effect is known as 'drag'. The ratio of lift to drag
is a measure of the efficiency of a wing-section. A well-designed wing will
have a L/D ratio at an angle of incidence of 4deg of about 16, i.e. the
lift effect in pounds will be 16 times that of the drag. The fundamental
equation of an aeroplane is R = KSV^2, where R = the resistance, K = a
constant (usually 0.003), S = area of surface, and V = the velocity in feet
per second. From this it will be seen that the resistance for the same area
increases as the square of the speed, which shows the importance of
reducing the resistance to the lowest possible degree if high speeds are to
be obtained. For this purpose it is necessary that the flow of air round
the component parts of the aeroplane caused by its passage should be as
little disturbed and broken up into eddies as possible. It is found that
the best theoretical shape for this purpose is a body of circular
cross-section tapering from front to rear, with the maximum cross-section
toward the _front_. The 'fineness ratio' (ratio of length to maximum
diameter) should be about 6 to 1, and the maximum cross-section situated
about one-third of the distance from the nose. Such a form will offer only
about 1/20 the resistance of a flat plate of similar cross-section, and is
known as a 'stream-line form'. The width of a wing from side to side at
right angles to the wind is known as the 'span', and the breadth from front
to back as the 'chord'. The ratio of span to chord is the 'aspect ratio'.
Owing to the increase in drag resulting from low aspect ratio (large chord
relative to span) the higher the aspect ratio the more efficient the wing.
This is in practice about 6, owing to structural difficulties in
constructing a wing of larger relative span. The essential parts of an
aeroplane are the wings, fuselage (body), tail (comprising fixed vertical
and horizontal surfaces behind which are hinged movable rudders and
elevators), and chassis, or landing-carriage. The majority of modern
machines are biplanes, i.e. with one set of wings superposed on the other
and connected by upright wooden members called 'struts'. Aeroplanes with
one set of wings only are called 'monoplanes'; those with three,
'triplanes'; with four, 'quadruplanes'; and with more than four,
'multiplanes'. Aeroplanes are also divided into 'tractor' and 'pusher',
according to whether the propeller is situated in front or rear of the
wings.
When the engine is started, the revolution of the propeller causes the
aeroplane to move along the ground until such a speed is reached (usually
about 35-50 miles per hour) that it is able to support its own weight in
the air when it leaves the ground. When in the air it is made to ascend or
descend by moving the elevators, which are operated by a vertical stick in
front of the pilot through control cables or levers. Steering to right or
left is effected by the rudder, which is operated by a foot-bar through
cables or levers. Lateral balance is obtained by means of 'ailerons' or
flaps on the outer extremities of the wings. If one wing tends to dip, the
aileron on that side is depressed. This increases the resistance of that
wing and so causes it to rise. By a combination of movements of the
elevators, rudder, and ailerons almost any evolution can be performed with
a modern aeroplane. A well-designed machine will, on cutting off the
engine-power, turn its nose slightly down and automatically assume its own
'gliding-angle' to the ground. The gliding-angle is the ratio of descent to
forward travel and is usually 1 in 12 to 1 in 14.
Speeds of 190 miles per hour have been attained and a height of 34,600 feet
reached. The greatest distance covered in one flight is the crossing of the
Atlantic--slightly more than 1900 miles--while an aeroplane has remained in
the air for 24 hours. Aeroplanes range in size from small single-seater
'scouts' with a duration of only some three hours, to large
multiple-engined machines with a weight, fully loaded, of from 15 to 20
tons. The essential feature of the aeroplane is, as already stated, that it
is heavier than air and therefore subject to the laws of gravity in the
event of engine failure. Its choice of a landing-ground is then dependent
upon its height at the moment and gliding-angle.
Aeroplanes are normally constructed throughout of wood, though steel is
occasionally used. The wings are built of wooden 'spars', of which there
are usually two along the length of each wing, connected together by wooden
'ribs'. The wings of a biplane are braced by the struts (see above) and by
wires. 'Landing-wires' support the weight of the wing on the ground, while
'flying-wires' prevent them folding upwards under the influence of the lift
in flight. 'Drift-wires' are to prevent the wings folding backwards under
the pressure of the air in flight. See also _Aeronautics_,
_Sea-planes_.--BIBLIOGRAPHY: H. Barber, _The Aeroplane Speaks_; H. Barber,
_Aerobatics_; Hamel and Turner, _Flying_; Borlase Mathews, _Aviation Pocket
Book_; Pippard and Pritchard, _Aeroplane Structures_; Judge, _Design of
Aeroplanes_; Judge, _Properties of Aerofoils_; Loening, _Military
Aeroplanes_.