AERONAUTICS

20

ĘSCHYLUS

side and rear fins, and a rudder in the rear. The Von Zeppelin airship, owned by the German government, is the largest of its kind, the gas bag being 420 feet long and 40 feet in diameter, with a gas capacity of between 300,000 and 400,000 cubic feet. It has attained a speed of 33 miles an hour, has made a trip of 220 miles and back, and has stayed up for seven hours.

The value of the dirigible airship is in the ability it affords to pass over an enemy's country and observe the disposition and movements of troops and the plans and character of defenses. The Hague conference in 1907 passed a rule forbidding the dropping of projectiles from balloons or aerial machines.

FLYING MACHINES

We pass now to the third and more hopeful method of aerial navigation. The problem here is to construct a machine which shall contain within itself a supply of energy not only sufficient to lift itself above the ground but also to propel itself through the air. The ablest students of this problem have abandoned all hopes of successfully imitating the bird: the model is too complicated. Accordingly, they have concentrated their study upon driving through the air at high speed a thin, light plane, having its forward edge higher than its rear edge, and supporting beneath it the engine which propels it.

If a railway car had open sides and a plane roof, sloping from the front to the rear, it is evident that the faster the car is driven forward the greater will be the tendency to lift off the roof of the car.

Imagine, now, that the car is very light but strong, that it contains a light but powerful engine, and that the light, sloping roof is strong enough to support the entire car and its contents; you will then have in mind the type of flying machine which was constructed by Maxim in England and improved by Langley in America. Since the experiments of Maxim and Langley, which were not practically successful, the problem has received the continuous study and effort of inventors and scientists. The first really successful result was achieved by the Wright Brothers of Dayton, Ohio, who after years of study and experiment produced an aeroplane which in the summer of 1908 made many successful ascensions at Fort Myers, near Washington, D.C., and LeMans, France, frequently remaining in the air for over an hour, changing direction and ascending and lighting at will. The machine is a biplane, the sustaining surfaces of which are parallel, one above the other, about 40 feet by 7. and is driven by a propeller placed amidships. In front is a biplane horizontal rudder for regulating the flight up or down, and in the rear a vertical rudder for steer-

ing. It is started by running on a monorail until sufficient impetus is secured to permit it to rise unaided.

Since 1908 marked advance has been made in perfecting the construction of the

WRIGHT BROTHERS AEROPLANE

R, rudder; LR, lifting and lowering rudder; P P, propellers.

aeroplane and in actual performances. In 1909 Orville Wright by a cross-country flight, carrying a passenger, met the last government test, and the Wright aeroplane was accepted for use of the signal corps of the army. They received $25,000 with a bonus of $5,000 for speed attained beyond 40 miles an hour.

Louis Bleriot of France invented a monoplane in which he crossed the English channel in 1909. Of biplanes the most successful French inventions are those of Henry Far-man and Leon Delagrange. An aeroplane in flight has now become a familiar sight in this country and in Europe. A distance flight of more than 350 miles, speed of more than 50 miles an hour and an altitude of more than two miles has been achieved. Among notable flights in this country are those of Glenn Curtiss from Albany to New York; of Brookings from Chicago to Springfield, 111. and of McCurdy from Key West to Havana.

While there is increasing interest, in aerial navigation, in the balloon and the airship, it is in the aeroplane that this interest centers, as giving promise of the "conquest of the air."

Aerotropism (in plants). A form of chemotropism (which see) in which oxygen is the directive agent.

Ęschines (ēs' ki-nėz), a noted Athenian orator, the rival and opponent of Demosthenes. After a varied career, as an actor on the stage and a public speaker of great eloquence, he was exiled and settled in Rhodes. Here he founded a school of eloquence. Three of his orations have come down to us, perhaps the most famous being that Against Ctesiphon. He died in Samos 314 B. C, at the age of 76.

Ęschylus {es'kt-lus) (525-456 B. C), the earliest of the great Attic tragedians. He was born at Eleusis, of a noble family, and took an honorable part in the Persian war. His first efforts at tragedy are said to have been suggested by the god Bacchus, who appeared to him while asleep in the fields. At the age of 41 he won his first prize in the dramatic contests populat among the Athenians, and during his life