Congress held in Rome during 1913, an Italian naval officer, G. Roncagli, proposed the preparation of an aeronautic map of the world, while an Austrian, T. Scheinpflug, suggested that photographs of the earth taken from aeroplanes should be converted into topographical maps. Statistics collected in the summer of 1913 showed that France led the way with a supply of 600 trained pilots, Germany coming second with 300, Italy third with 175, Great Britain fourth with 135, Russia fifth with eighty, Japan sixth with twenty, United States seventh with nineteen, and Mexico eighth with five. The war made aviators by the tens of thousands. Until 1914, an aviator was a rare person; it was a great distinction to hold a pilot's license; few persons had gone aloft in airplanes. But with the call for fighting aviators, the various countries soon trained thousands of young men for flying duty.

The Information Branch of the United States Air Service in 1919 prepared for the Manufacturers' Aircraft Association a tabulation showing the comparative safety of flying when reasonable precautions are observed. The conclusions were based on records kept at the various army training fields, and tend to show that the safety of the airplane is such as to warrant the interest of the business world. Summed up, the army records show that there was only one fatality for every 2,919 hours of flight, or the equivalent of almost 235,000 miles of travel in the air. Even then, allowance must be made for the intensiveness with which the wartime training was carried on. An analysis of the accident report showed that the greater majority of the mishaps at the flying fields were the result of bad judgment or physical difficulty experienced by the student, and not through structural weakness in the plane or engine. A recapitulation of the reports apparently substantiates this view, as there were only 298 fatalities among 20,142 aviators. The increasing safety of the airplane received further corroboration by experience gained in Great Britain during the first year after the war. During that year (1919) a total of 70,000 passengers were carried in 38,954 flights with but one fatal accident. The number of miles flown was 734,200 and the goods carried totaled 116,498 pounds. No fewer than 114 aerodromes were licensed and 519 machines registered during the year. Commenting on these figures, Major Gen. Sir F. H. Sykes, controller general of civil aviation, was quoted as saying: "We have conquered the air and our immediate task is to exploit our victory in the interest of commercial development." Of paramount importance is the personal equation or temperamental composition of a successful aviator. A perfect knowledge of all the rules of the game of flying will not save a man who lacks confidence in himself and is inclined to hesitate. A half-second of indecision may be fatal. Initiative, the sporting instinct and a certain irresponsibility, qualities inherent in American youth, have been found of far greater value in the air than the logical, scientific, severely disciplined character of the Germans, and account for the superiority of the Allied aviators in general. The most eminent of British scientists have devoted special study to the psychological and physiological aspects of flying. One authority says that good eyesight, normal hearing, good "muscle sense," and equilibration are indispensable qualifications. But most important of all is the right temperament-not an easy thing for a medical board to examine. Of the types-the imaginative and the unimaginative-the imaginative youth is said to make the better pilot if he can keep his imagination under control. He who has

led an outdoor life and has played many games is most likely to pass the test, although, of course, there are exceptions. Splendid, powerfully built sportsmen have been known to fail altogether, and anaemic, frail-looking youths of the student type have blossomed into brilliant pilots. "It is exceptionally interesting. . . that the natural desire of the flying man to diminish the boredom of aerodrome flying by the practice of 'stunting' was met by the French military authorities with precisely the same discouragement as was accorded to the corresponding enthusiasts by the British authorities in pre-war and early war days. The 'stunts' which in 1918 are dignified by the name of 'aerobatics,' and which eventually formed the basis of the tactics of military flying were . . . rigorously forbidden by the French, and military flyers were punished for having dived too steeply or turned too quickly. . . . We may also note that the noble art of looking with a blind eye upon a military order has saved British aeronautics from the extinction which would have been its fate had our fliers suppressed with self-denying acquiescence their instinctive desire to acquire the art of rapid manœuvring, looping, diving, spinning, fluttering, rolling and the like. In France the same seems to have taken place. Those who disobeyed the order acquired the art of manœuvring, and those who acquired the art of manoeuvring survived. Thus even in so tightly organized an institution as the army can we detect the advantage of individualist effort."-Future of aeronautics (London Times Literary Supplement, Jan. 9, 1919).— "A considerable controversy raged in the press and elsewhere a few months before the cessation of hostilities [1918] on the subject of equipping the aeroplane with parachutes as a life-saving device. In the airship service this had been done for two years. The best type of parachute available was selected, and these were fitted according to circumstances in each type of ship. The usual method is to insert the parachute, properly folded for use, in a containing case which is fastened either in the car or on the side of the envelope as is most convenient. In a small ship the crew are all the time attached to their parachutes and in the event of the ship catching fire have only to jump overboard and possess an excellent chance of being saved. In rigid airships where members of the crew have to move from one end of the ship to the other, the harness is worn and parachutes are disposed in the keel and cars as are lifebuoys in seagoing vessels. Should an emergency arise, the nearest parachute can be attached to the harness by means of a spring hook, which is the work of a second, and a descent can be made. It is worthy of note that there has never been a fatal accident or any case of a parachute failing to open properly with a man attached."— G. Whale, British airships, past, present and future, pp. 31-32.

1910-1920.-Development of the seaplane.All metal planes.-Liberty motor.-Airplane types.-Hangars and floating airdromes.-The first float seaplane that left the water under its own power and returned thereto was built by Henri Fabre, of France, the trials taking place on March 28, 1910, near Marseilles. Thence the development of the seaplane was chiefly due to the persistent efforts of Glenn H. Curtiss, of Hammondsport, N. Y., who produced the first practical float-seaplane in 1911 and developed the following year, simultaneously with M. Denhaut of France, the boat seaplane, or flying boat. The seaplane differs from the land machine, in having the car shaped like a boat, so that it can alight on the water, upon which it floats, and hydro

planes permit it to arise without difficulty. In the United States and other navies, most large ships carry at least one seaplane, while special vessels carrying ten to twenty-five planes accompany large naval forces. "At first glance, the giant seaplane of our Navy appears formidable while resting on the water, and still more so when hauled up on the shore where its boat-like body lies fully uncovered to view. In flight it does not seem so large; indeed, it might well be mistaken for the smaller flying boats by the layman, since all aircraft are deceptive while in flight. But viewed close up there can be no mistake about size of this craft, with its 110-foot span, two Liberty motors developing from 400 to 500 horse-power each and driving propellers 102 feet in diameter, and a body over 50 feet in length. The fact is that the body, or hull, is nothing short of a 50foot yacht, but instead of velvet cushioned berths and other comforts its interior is given over to a tangle of braces, wires, steering and controlling devices, instruments, a wireless station, a six-station intercommunicating telephone system, fuel tanks and guns, all of which are the means of combating the U-boat and of carrying out longdistance patrols at sea. On the water the seaplane develops a speed up to 50 miles an hour, and the moment it slips off the surface and soars upwards the speed increases to 100 miles an hour. As in every other heavier-than-air machine, the naval aircraft engineers have had to secure strength in their structure while keeping a strict eye on the weight. Thus the required strength of every piece of material entering into the construction is determined by exhaustive tests; and in a hundred ways both wood and metal parts are thinned and lightened until this maximum of strength is preserved and the minimum weight reached. A completed wing, painted in battleship gray, looks like a solid steel armor plate; but strip off the fabric which carries the paint and inside is seen a skeleton frame of spruce webs and piano wire braces. The webs, or ribs, which form this frame are set between full length beams, these beams being reduced to the smallest possible size consistent with the great strain to which they are subjected.. Every part is carefully varnished as if for display and the whole covered by fabric stretched until it rings like a drum. The strength is there, to be sure, but the weight is not; so that a 40foot wing, eight feet in width, which appears to weigh at least a ton, is readily lifted by one man. This same construction is followed in the entire seaplane. The keel is but little more than a strip of wood, but a perfect system of bracing makes it strong as a steel girder. . . . There is no haphazard work about the building of one of these boats. Every piece of wood or metal is given an individual part number. Each one is designed for a particular place and the use of jigs and dies makes possible a degree of standardization of wood and metal parts which is as near perfect_as_can be reached in aircraft production."-A. C. Lescaraboura (Scientific American, Dec. 14, 1918, pp. 481, 486).

"Canvas, wood and a maze of bracing wires have been the materials of the airplane builder ever since the Wrights flew their first machine over the sand dunes of Kitty Hawk. From time to time some one has come forth with the suggestion that metal be used instead of wood, but the suggestion has received little serious thought. The bracing wires have been slowly reduced in number by improved designs; but the wood and canvas might have remained to the present day if German aircraft constructors had not departed from the time-honored idea and experimented with metal

planes. During the closing months of the war German airmen appeared over the Allied lines flying marvelous all-metal machines. At the time these were considered freaks of little if any real value. Aeronautical men outside of Germany were only too hasty in their condemnation of the allmetal German machines. How, they asked, could one make a practical all-metal machine? Was not the weight of even the lightest aluminum alloy considerably heavier than wood, matching strength with strength? And so the German aircraft constructors stole a long march on the aircraft constructors of all other nations. With the ending of hostilities certain all-metal German machine: came into the possession of the Allied experts, and then the advantage of this new form of construction became known. Still, it was a much mooted question whether such construction was practical in any machine other than one intended for aerial combat, wherein engine power was almost unlimited since the main consideration was performance irrespective of expense.

"Several weeks ago [June-July, 1920] an allmetal monoplane made a new American record This machine, the JL-6, is nothing more than a German Junkers' limousine six-seater-one of several machines of this type brought to these United States by an enterprizing business man who has the future of aviation at heart. The speed of the all-metal monoplane was surprizing. But most surprizing was the low fuel consumption. This seemingly heavy machine excelled by a good deal the efficiency of the relatively flimsy wood and canvas planes. Germany has scored a very decisive success in airplane construction. To deny that fact would be foolhardy. It appears that Dr. Junkers of Germany has gone ahead along new lines, ignoring the old misconceptions about the heaviness of metals and the necessity of canvas for the wing surfaces. He has produced machines with thick, unbraced cantilever planes, corrugated aluminum alloy for the wing surfaces, and allmetal struts. At one stroke he has wiped out canvas, wood and the maze of wires, and in their stead he has introduced tremendous strength, unapproached wearing qualities, fireproof characteristics, and unrivalled efficiency. The wood and canvas airplane-the airplane which we know so well-is a frail structure compared with this allmetal machine. The wood and canvas machine has a life of about a year or two with steady use; the all-metal airplane, with little to deteriorate from exposure to the elements, has a life of several years. The all-metal machine can withstand hard landings, which would cost the usual airplane smashed members. Germany is not confining the all-metal construction to small airplanes. Already she has constructed several giant airplanes, one of the largest being the Zeppelin-Staaken monoplane. This machine proved one of the greatest surprizes in store for the Allied officials who visited Germany right after the armistice. It is powered with four 260 horse power motors. mounted as tractors on the leading edge of the wings. The mechanics can actually get about inside the monoplane wings and repair and adjust the engines while in the air. This giant accommodates eighteen passengers, or it can carry a one-ton load of useful cargo. All comforts are included for the passengers-easy chairs, large windows, pantry, lavatory, a luggage compartment. and a sleeping cabin which also serves as a collision buffer in a bad landing.”—Independent, Sept 4, 1020, p. 282.

"When the war first broke out, airplanes were fitted with 100 horse-power engines. Very soon they were found to be insufficient and engines of

125 horse-power were made. The engine power then gradually increased to 150, 175, 200, 250; and it was about in that neighborhood when Major Hall and Mr. [J. G.] Vincent were called upon to furnish the United States standard motor. It was felt that a motor should be designed so far ahead in power of anything else that had been produced that, by the time it could be turned out in quantity, it would still be well in the lead. Accordingly, a horse-power of between 350 and 400 was sought and the size of the cylinders was changed from 4 x 6 to 5 x 7. Because of the larger cylinders required in the new motor, the angle of the V was changed from 40 to 45 degrees. The larger pistons and cylinders required slightly greater clearances. . . . These and other slight modifications were thoroughly discussed and decided upon by the two motor experts who worked unceasingly and arrived at the finished design in a conference lasting five days. They had a herculean task before them and deserve the highest praise for the successful outcome of their efforts. As soon as the conference was over, telegraphic instructions were sent on to the Packard plant and work was started immediately upon the new motor. Even before blue prints arrived the wood model was prepared in the general form .nd essential features of the new motor. Work on the new engine was pushed at the highest speed possible, and on the third day of July, it was completed and shipped to Washington. The next day it arrived there, on the Nation's birthday, and was christened the 'Liberty Motor.'

"After the first experimental motor had been completed it was subjected to a great many trying tests, and was found to be exceedingly efficient and very light. It developed a horse-power of considerably over 400 and its weight was but little over 800 pounds. Its weight per horse-power was therefore about two pounds, which is much lighter than the majority of airplane motors. On endurance tests it stood up wonderfully. It was tested at the summit of Pike's Peak in order to determine its action under conditions of rarified atmosphere-and proved very satisfactory. At the Bureau of Standards in Washington, a special room was set aside in which a partial vacuum was created equivalent to that which exists at the maximum height to which an airplane engine has been carried. In this room the engine was found to operate perfectly. At one of its first altitude tests in a plane the American record for altitude was smashed. Not until September was the order to proceed with the manufacture of the Liberty Motor definitely given, and immediately work was started in the Packard plant. It is interesting to note that the first experimental motor was delivered to the Government on the 4th day of July, and the first production motor was sent to Washington on Thanksgiving Day. This, however, did not mean that the production problems had all been solved. . . . The motor which was delivered to the Government on Thanksgiving Day developed a number of small troubles. One of these was the difficulty of lubrication, and eventually it was found necessary to change the scupper system to the original forced lubrication system. But the most important change was made in the production of the cylinders. In the first Liberty Motor, the cylinders had to be bored from the solid-an operation that was very costly in time and money. This, however, was a copy of the best foreign engineering practice, and was followed as a necessary detail by our engineers. It was at this juncture that the engineers of the Ford Motor Car Company made a notable contribution. They developed a cylinder forged out of steel tubing, which

enabled the manufacturers to turn out the cylinders at very low cost and in exceedingly large quantities. Seamless steel tubing is used, and this in but four operations under the forge press and bulldozer, is converted into a headed and flanged cylinder blank on which a minimum of machining need be done. The manufacture of these cylinders was not undertaken until the end of January and [later were] turned out in very large quantity. One of the difficulties encountered in the Liberty Motor had to do with the form of ignition. In the original Packard motor, the 'Delco' system of ignition was used. This consists in generating current with a small electric generator geared to the engine shaft and then transmitting the current by means of a pair of distributors to the spark plugs. Magneto ignition was tried, but it proved impossible to design a single magneto which would operate with the irregular timing required in an engine in which the cylinders were set at the unusual angle of 45 degrees. A single magneto could not be used and so a battery of four magnetos had to be employed. This added somewhat to the weight of the engine. Then further difficulties were encountered. Owing possibly to the vibration of the engine at high speed, the magnets of the magneto showed fatigue and gradually lost their magnetic property. So that eventually it was decided to return again to the original system of ignition. It is rather remarkable that in a number of very important features, it has been necessary to revert to the original design. . . . The efficiency of the Liberty Motor is not to be questioned by anyone who has examined it thoroughly. It is far more powerful than any other airplane engine ever produced on a quantity production basis. It exceeds in power all but a few experimental machines. Although rated at 400 horsepower it has shown on test as high as 485 horsepower; and its weight is 820 pounds.”—Scientific American, June 1, 1918, pp. 500, 515.-"England, France, and Italy had reached the point where they could build airplanes much faster than they could build engines, when hostilities ceased. Both countries had accepted the Liberty motor as the best airplane engine, and both were building their planes to fit this American engine, when the order came to cease firing. How much faster we were building engines than were our European associates is indicated by the fact that the largest day's production of the engine most closely approximating the Liberty in quality, the RollsRoyce, was fifty-nine, while the Liberties were being turned out at the rate of 150 a day! In October, America's production of airplane engines was 5,603. This is more than the total production of France and England together for the whole four years of the war!"-World's Work, Feb., 1919, p. 473.

King and Leslie give the following classification of types of airplanes:

Monoplane. Having one main lifting surface. Biplane. Having two main lifting surfaces mounted one above the other.

Triplane. Having three main lifting surfaces mounted one above the other.

Tractor. A tractor airplane is drawn forward by means of a propeller placed in front of the main lifting surfaces.

Pusher. A pusher airplane is thrust forward by means of a propeller at the rear of the main lifting surfaces.

Aeroplane. A land machine equipped with a landing gear with free running wheels, which enable it to take off and land on the earth.

Hydro-aeroplane (or seaplane). A water machine equipped with either single or double floats

which enable it to take off and alight on water Flying boat. Equipped with a boat-shaped hull which takes the place of fuselage and pontoons of a hydro-aeroplane.

Still

The term hangar is applied to the structures in which flying machines are stored. There are many and varied types constructed to meet the needs of the various aircraft, those built to house airplanes necessarily being of different construction from those built to enclose the huge modern airships. During the World War, to meet the needs of the navy, floating carriers were constructed. These might practically be called floating airdromes, since, besides carrying the airplanes, they also served as the field for their starting off and alighting. "The first one of these was merely a large commercial steamer equipped with a deck on which the airplanes could take off and land, with a hangar deck immediately below this in which the airplanes could be kept ready for flight, and with machine-shop facilities, spare parts for the airplanes, and all other accessories for keeping them in condition on the ship. The first carrier was the Argus, which had a deck 535 feet long and 68 feet broad. Her hangar held twenty airplanes, or practically a squadron. Her speed was only twenty knots. It was evident at once that any vessel having such a slow speed would not only be a prey to other warships, but also to submarines-not to mention destruction by hostile air attack-and there were many other things about this carrier which were not satisfactory, as it was the first attempt in this direction. The next carrier to be built was a warship being constructed for a South American country, which was transformed into a carrier and renamed the Eagle. This ship is capable of carrying about forty airplanes in her hangars, or two squadrons. another carrier is the Hermes, with a speed of twenty-five knots; while more are being built. The British, however, recognized that these vessels could not operate far enough in advance of their fleets so as to go out and fight for control of the air, but would have to stay near the fleet and be protected, because their speed was not great enough to protect themselves. Consequently, they took the vessels that were most readily available, that had the required speed and at the same time fighting power to ward off other vessels-that is, their battle cruisers-and transformed them into a combination carrier and battle cruiser. They are now reported to have a division of battle cruisers, or four of these high-speed vessels, equipped with airplanes. They all have a speed of about thirty-five knots, or forty miles an hour; and have very heavy gun power-equal to that of any battleship and with the airplane carriers attached to them they have the power of concentrating the equivalent of one or more groups of pursuit aviation wherever they desire. . . . It should be noted that the whole development for the use of aircraft over the water is not in air tactics, in types of airplanes particularly, or in the securing and training of air personnel; but is essentially a development of floating airdromes. It is, therefore, evident that floating airdromes must be made to suit the requirements of the airplanes first-that is, if we are going to fight and drive out of the air an opposing aviation, we must bring to bear against it airplanes that can do the work. Next, the airplane carriers must be able to defend themselves against attack on the water. As to the first requirement, the airplane carriers should be capable of accommodating a complete tactical unit, or one group of 100 pursuit airplanes; and in the second case, in order to be able to defend itself, and be capable of taking the offensive quickly, it

should have a speed of at least forty knots, or around fifty miles an hour, which is entirely possible at this time. To answer these requirements, the airplane carrier should be about 1000 feet in length, with a landing deck of this size. Its width would be over 100 feet and it could be equipped with all the facilities for handling the airplanes quickly either by day or by night. Even one airplane carrier of this kind would give the side possessing it complete control over the water at the present time, and render an opposing fleet incapable of acting with its observation aviation." -W. Mitchell, Aviation over the water (American Review of Reviews, Oct., 1920, pp. 393-395). -For the aviator, the problem of the landing field is of vital importance, as, next to the actual trials of flight itself, the greatest danger is in making the landing. To alight safely, a landing field must be properly constructed, and in recognition of this situation, municipal and private corporations are beginning to construct fields to meet the requirements of aviation. The word "hangar," which is French, signifies a shed, barn or outhouse.

1914-1918.-Great European progress during World War.-Growth of American air service.Great progress was made in aviation during the World War. So thoroughly did the airplane prove its military worth on the battlefields of Europe, that all possible efforts and facilities were concentrated on the development of the airplanes of the belligerents. The airplane was improved by leaps and bounds. Airplanes became "the eyes of the army and navy." "In the years before the war it had become the fashion to announce that the next European conflict would witness a phenomenal use of aircraft. Ingenious romancers had pictured an Armageddon in the clouds, and lovers of peace had clung to the notion that the novelty and frightfulness of such a warfare would make the Powers of the world hesitate to draw the sword. The results have been both below and in excess of expectation. The air was a realm of pure guesswork, for in the Tripoli and Balkan wars there was no serious aerial service, though various adventurers experimented in the new arm.

France led the way in aerial experiment, and her government between 1909 and 1914 acquired the largest air fleet in the world. Her aviators were brilliant performers, especially in long-distance flights, but they were not thoroughly absorbed into the military machine. They had less knowledge of the tactical use of aircraft than of their mechanical capabilities, and the organization of the French Air Corps was severely criticized by the Committee of the Senate just before the war. ... There was no government standardized pattern, and hence supply of spare parts and accessories became a difficulty. The French airmen had brilliant technical skill and endless courage-men like Garros and Pégoud [the latter was the first to 'loop the loop'] had no rivals-but as a corps they were not so fully organized for war as their neighbours. [See also LAFAYETTE ESCADRILLE.] The Germans had preferred at first to interest themselves rather in airships than in aeroplanes. but their military advisers were well aware of the value of the latter, and had prepared a strong corps. The German aviator could not fly as well as the French; on the whole he had not as useful a machine; but he understood perfectly his place in the military plan. He was thoroughly trained to reconnaissance work, and especially to the task of range-finding for the field guns. The Austrian air service was much inferior, though it contained some dashing pilots. The Russian had enormously improved, under the Grand Duke Alexander, but it suffered from a shortage of ma