easily be surpassed in size. The largest hot air balloon, La Flesselle, launched at Lyons in 1784, measured 100 feet in diameter by 130 feet high. Comparable with this in size was the hydrogen balloon, The Prussia, of 300,000 cubic feet volume, with which Prof. Berson and Dr. Süring rose to the highest elevation yet attained by man-35,600 feet, or nearly seven miles. The largest hydrogen balloon, cubing 450,000 feet and carrying forty passengers at once, was used by Giffard to give sightseers a view of Paris at the Exposition of 1878.

The longest voyage in a spherical balloon yet recorded is that of Emile Dubonnet and P. Dupont. Sailing from La Motte-Brenil, France, Jan. 7, 1912, they landed next day at Soko

lowska, Russia, after a continuous journey of 1954 kilometers, or 1216 miles. The previous world's record was held by Count de la Vaulx. Starting from Vincennes, France, in October, 1900, he landed at Korosticheff, Russia, having traversed 1,193 miles in 354 hours. A close second to this record was made by A. R. Hawley in his spherical balloon America, aided by Augustus Post, in the Gordon Bennett International Balloon Race of 1910. Sailing from St. Louis, October 17, they drifted 1,173 miles from their starting point, and landed in a great forest at Peribonka River, North Lake Chilogoma, Canada, where they were lost for several days.

BALLOONS.

for Prof. Charles, and had first made rubber varnish, devised and built the first elongated dirigible. This was a

a

melon-shaped silk bag, 52 feet long by 32 feet in diameter, supporting longish car propelled by six silken oars and guided by a silk rudder. It was a successful dirigible, but too slow to be of any value, for it was driven by hand power and traveled at only a walking pace.

Gen. Meusnier that same year devised a similar shaped balloon, but having coaxial screw propellers between the car and bag, to be actuated by eighty men. The hull comprised a melon-shaped hydrogen bag inside a slightly larger air bag always pumped full and taut so as to resist deformation. Stablizing planes placed on the outside, as in the modern dirigible, were to control the poise of the vessel. The buoyant hull and suspended car were to be kept in alignment by suitably inclining and crossing the suspension cords. The Meusnier design was indeed a creation of fundamental importance which, for want of engine power, had to wait upwards of a century before it could be practically employed.

The first torpedo-shaped balloon was Jullien's model of 1850, made of gold beaters' skin, measuring 23 feet long and weighing 21⁄2 pounds. It was driven by clock-spring-actuating twin propellers at either side of its bow, and had a double rudder at its stern. It could navigate steadily against a moderate wind. Aerodynamically this tiny model excelled in design all other dirigibles produced during the first century of aeronautics, and was the harbinger of the swift modern air cruisers of the most effective shape and equipoise.

During the remainder of the nineteenth century steam, electric and gas motors were in turn applied to the propulsion of airships, but with meager success. In 1852 Giffard, in a spindleshaped balloon 143 feet long by 39 feet in diameter, and driven by a threehorse-power steam engine actuating an 11-foot screw, voyaged from Paris at a sustained speed of six miles an hour through the air and with good control. In 1872 the German Haenlein, with a cucumber-shaped coal gas balloon 164 feet long by 30 feet in diameter, driven by a gas engine taking fuel from the envelope, and actuating a single screw, attained a speed of ten miles per hour. In 1884 Renard and Krebs, in a torpedo-shaped dirigible 165 feet long by 27.5 in major diam

eter, driven by an electric battery motor, actuating a screw propeller, made the first return voyage against a moderate wind. The vessel showed excellent control, attained an average speed of 14.5 miles an hour, and was of model workmanship; but for lack of power it was practically abandoned till the advent of the automobile engine.

In 1898 Santos-Dumont, emulating the German Wölfert, who in 1880 first attempted to drive a dirigible with a benzine engine, sailed aloft in a spindle-shaped balloon 82 feet long by 11 feet in diameter, driven by a motor-cycle engine of 32 horsepower, carried in the car suspended beneath the envelope. Finding this vessel manageable and swift enough to make his clothes flutter, and amply rigid when its balonet or internal air cell was properly inflated, he in subsequent years built fifteen more dirigibles of various designs. The speed of the best of these varied from fifteen to upwards of twenty miles per hour. They may be considered as the successful prototypes of the great non-rigid air cruisers which so quickly followed in France, Germany and elsewhere.

In 1900 Count Zeppelin, emulating the Austrian, Schwartz, who in 1897 first tentatively drove a rigid metal balloon with a petrol motor, launched the first of his huge rigid dirigibles. Its hull, which was framed of aluminum and contained seventeen compartments holding buoyant hydrogen bags, measured 416 feet long, 38 feet across, cubed 400,000 cubic feet, weighed nine tons, and had a displacement of ten tons. It was driven by two petrol engines actuating four screw propellers mounted directly on the underside of the hull, two forward and two aft. Subsequently larger vessels, with passenger compartments running along the bottom of the hulls, accommodating twenty to thirty passengers, were built and powered with engines adequate to attain velocities of over forty miles per hour. The large vessels have required for inflation nearly 700,000 cubic feet of hydrogen, have weighed some fifteen tons and lifted four or five tons of useful load, have voyaged continuously twenty to forty hours. and have made continuous journeys of 500 to 1,000 miles in length. Zeppelin X., called the Schwaben, a regular transportation airship with accommodations for 24 passengers, made

1911 over 100 trips, aggregating 8,500 miles and carried 2,300 persons. Regular excursion tickets can now be purchased in New York by outgoing tourists which, on presentation at the Zeppelin airport at Friedrichshafen, entitle the bearer to an airship voyage, usually conducted on schedule time, over some of the most beautiful and interesting regions of Germany and with the accommodations of a modern palace car. The above table gives the dimensions, power and speed of Count Zeppelin's various dirigibles up to 1912.

Rivaling these unique rigid dirigibles, at least in celerity and control, if not in size, are the great non-rigid dirigibles of Gross and of Parseval in

Germany, of Clement and of Julliot in France, and of the national government in Italy. These all comprised elongated silk bags, more or less whale shaped, from which were suspended the car carrying the crew and passengers and the mechanism of propulsion and control. Scores of these large non-rigid dirigibles sprang into being for sportive or military use, powered sufficiently to run all day, to voyage hundreds of miles, and to attain speeds of thirty to forty miles an hour. The Parseval in particular has an excellent reputation for the speed and precision with which it carries passengers on schedule time above the city of Berlin and over some of the most interesting historical places in Germany.

For many decades two kinds of passive flight have been recognized in nature, and have been understood to be achievable by man. One is volplaning, or gliding by aid of gravity or acquired momentum; the other is soaring, or gliding by force of the wind without loss of altitude. Human

volplaning has been so far perfected as no longer to be a novelty; human soaring is a much neglected art, though doubtless capable of very great development.

The permanent art of passive manflight dates from Otto Lilienthal's experiments near Berlin in the early nineties of the last century, though

long previous to that time some wonderful feats of gliding and soaring, of both men and models, were reported by reliable witnesses. Lilienthal made numerous glides several hundred feet in length, down hill slopes, sometimes pausing in the air or rising considerably above his launching place. Sometimes also he wheeled about and returned nearly to his starting point. At first he used a monoplane glider, then a biplane, in each case controlling his poise in the air by shifting his weight as he hung by his arms underneath the kite-like motorless craft. He finally prepared to convert his glider into a dynamic aeroplane by

adding a light engine; but in an unlucky glide his structure gave way and dropped him to his death among its tangled wreckage-the protomartyr!

Lilienthal's work was continued by various disciples, mainly American, who perfected his structural designs and means of balance. Chanute and Herring in the latter nineties developed the familiar Chanute biplane, whose Pratt truss arrangement of two superposed concave surfaces is now commonly used in many types of power aeroplanes. They, too, maintained their aerial poise by shifting their suspended weight. Early in the twentieth century the Wright brothers, of Ohio, and Prof. Montgomery, of California, introduced in practice the modern dynamic system of controlling an aeroplane in passive flight without shift of the operator's weight, though, broadly speaking, their devices had been previously invented and published by various other votaries of aviation, as will be shown later.

The records for volplaning have not been kept with much care, but some are well attested. Lilienthal, Chanute and Herring and the Wrights all performed short flights of usually less than 1,000 feet, along sloping ground. Montgomery in 1905 launched from a balloon 4,000 feet in air a glider bearing on its back a dauntless aeronaut, Maloney, who by means of wing warping and a double rudder guided it, with many a playful dip and wheel, securely down to a designated spot, where he landed in safety. With a like aerial glider another Montgomery aeronaut cut corkscrews in the air. The record for volplaning in a power machine, which really becomes a glider when the motor stops, is held by Lincoln Beachy, who during the Chi

cago meet of 1911, glided sheer down to earth in a Curtiss biplane from an elevation of 11,642 feet.

The records for soaring are briefer, and some are not so well attested. In 1859 Capt. Le Bris, piloting a glider patterned after an albatross, soared 300 feet high and descended safely to earth. This on the authority of De la Landelle, who wrote a history of aeronautics, published in 1884, and who had the account from Le Bris's neighbors. Mouillard, nearly twenty years ago, soared 138 feet over a prairie after an initial run and jump across a roadside ditch with a glider strapped to his waist. Many recent aeroplanists have been carried well upward by rising wind currents. During the gliding experiments of Chanute and Herring one of the operators was raised by the wind some forty feet high, then landed almost in his tracks without serious shock. Lateral glides along the hillside were also made, one forty-eight seconds in length, which showed the possibility of patrolling to and fro in such places. Mr. Atwood relates that while flying over a mountainous country he once encountered an upsloping current which lifted him over 1,000 feet high. Orville Wright was supported on such an ascending current above a hill slope for nearly ten minutes, sometimes stationary, again gliding forward or backward, and sometimes rising to a considerable elevation above the starting point. Ludolph Schroeder relates that in May, 1908, he launched from the Palisades, on the Hudson, a riderless glider six feet long, pine made of one-inch boards, and saw it caught up by the oncoming wind and carried hundreds of feet high and many thousand feet to the west of the river.

From time immemorial aviation had been cultivated in a crude, tentative and unpromising fashion before any noteworthy and definite progress began to be recorded. Such progress dates from the first decade of the nineteenth century. Prior to that time many volant devices had been tested, and had little flying achieved, but no permanent and substantial contribution to either the science or art of dynamic flight had been transmitted to succeeding generations.

some

been

England made the first substantial

Mr.

contribution to the science of aviation. In 1809 and 1810 Sir George Cayley published in Nicholson's Journal, now the Philosophical Magazine, a paper describing his experiments with large aerial glider models, and setting forth the principles of design conducive to inherent stability. He clearly conceived and explained the advantage of placing the wings of an aeroplane at a dihedral angle to one another, as soaring birds do, to maintain a pendulous lateral equilibrium, and he em ployed that device. He anticipated sixty years the Frenchman, Pér