Part 10

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_.

AEROSTATIC PRESS, a contrivance for extracting the colouring matter from dye-woods and for similar purposes. A liquid intended to carry with it the extract is brought into contact with the substance containing it, and a vacuum being made by an air-pump suitably applied, the pressure of the atmosphere forces the liquid through the intervening mass, carrying the colour or other soluble matter with it.

AEROSTAT'ICS, that branch of physics which treats of the weight, pressure, and equilibrium of air and gases. See _Air_; _Air-pump_; _Barometer_; _Gases, Properties of_; _Hydrostatics_; _Meteorology_; &c.

AEROTHERAPEUTICS is the treatment of disease by atmospheres artificially prepared and differing from the normal in compression or pressure or temperature. It is divided into:

1. _Medical atmospheres_ artificially produced by changing the proportions of the normal gases of the atmosphere, or by adding gases to the atmosphere. These are applied by inhalation in various ways:

(a) By the inhalation of gases--_ether_; _chloroform_; _nitrous oxide_ (see _Anaesthetics_). _Oxygen_ under pressure in a cylinder, with outlet applied close to the patient's mouth and nose, is used in severe cases of pneumonia, cardiac disease, or wherever breathing is difficult. _Amyl nitrate_ is inhaled on the breaking of the glass capsules in which it is contained close to the patient's mouth; this treatment is used in cardiac disease and other conditions to recover blood pressure. _Chlorine_ and _iodine_ are used in cases of throat and bronchial affections by inhaling the vapour itself for a short time, or by inhaling air strongly impregnated with the substance.

(b) By inhalation of substances requiring heat for volatilization, e.g. _mercury_ and _sulphur_. The patient, enveloped in a sheet, sits on a chair, while the substance, placed in a vessel on the floor inside the enveloping sheet near the patient, is heated by a spirit lamp or similar method. _Mercury_ is used for chronic and syphilitic laryngitis and pharyngitis; _sulphur_ for scabies and other skin diseases.

(c) By inhalation of steam or warm-water vapour with a drug added. Apparatus of various kinds is used, the simplest of which is a wide-mouthed jug filled with boiling water to which the drug has been added. The patient takes a deep breath, drawing the vapour into his mouth up a napkin arranged in the form of a tube. More complicated forms of apparatus are steam-sprays and nebulizers for laryngeal and bronchial troubles.

(d) Cold medicated sprays and inhalations. Throat- and nose-sprays are much used, also sprays for the administration of local anaesthetics (ethyl chloride). Respirators are made of wire gauze with cotton wool or a sponge; the substance is poured on and inhaled by the patient.

For (c) and (d) the following drugs are used: carbolic acid, creosote, terebine, thymol, eucalyptol, zinc sulphate, in phthisis and bronchial affections; and eusol, izal, lysol, &c., for disinfection and fumigation.

2. _Changes produced by variation in barometric pressure considered in treatment of disease_:

Normal barometric pressure at sea-level, 29-30 inches; at Davos (5200 feet), 25 inches; at summit of Pike's Peak, Colorado (14,000 feet), 17 1/2 inches; in balloon ascent (Glaisher and Coxwell) of 29,000 feet, 9 3/4 inches.