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Introduction to the History of Science

<h2>CHAPTER XVII</h2> <h3>SCIENCE AND INVENTION—LANGLEY'S AEROPLANE</h3> In his laudation of the nineteenth century Alfred Russel Wallace ventured to enumerate the chief inventions of that period: (1) Railways; (2) steam navigation; (3) electric telegraphs; (4) the telephone; (5) friction matches; (6) gas-lighting; (7) electric-lighting; (8) photography; (9) the phonograph; (10) electric transmission of power; (11) Röntgen rays; (12) spectrum analysis; (13) anæsthetics; (14) antiseptic surgery. All preceding centuries—less glorious than the nineteenth—can claim but seven or eight capital inventions: (1) Alphabetic writing; (2) Arabic numerals; (3) the mariner's compass; (4) printing; (5) the telescope; (6) the barometer and thermometer; (7) the steam engine. Similarly, to the nineteenth century thirteen important theoretical discoveries are ascribed, to the eighteenth only two, and to the seventeenth five. Of course the very purpose of these lists—namely, to compare the achievements of one century with those of other centuries—inclines us to view each invention as an isolated phenomenon, disregarding its antecedents and its relation to contemporary inventions. Studied in its development, steam navigation is but an application of one kind of steam engine, and, moreover, must be viewed as a[Pg 232] phase in the evolution of navigation since the earliest times. Like considerations would apply to railways, antiseptic surgery, or friction matches. The nineteenth-century inventor of the friction match was certainly no more ingenious (considering the means that chemistry had put at his disposal) than many of the savages who contributed by their intelligence to methods of producing, maintaining, and using fire. In fact, as we approach the consideration of prehistoric times it becomes difficult to distinguish inventions from the slow results of development—in metallurgy, tool-making, building, pottery, war-gear, weaving, cooking, the domestication of animals, the selection and cultivation of plants. Moreover, it is scarcely in the category of invention that the acquisition of alphabetic writing or the use of Arabic numerals properly belongs. These and other objections, such as the omission of explosives, firearms, paper, will readily occur to the reader. Nevertheless, these lists, placed side by side with the record of theoretic discoveries, encourage the belief that, more and more, sound theory is productive of useful inventions, and that henceforth it must fall to scientific endeavor rather than to lucky accident to strengthen man's control over Nature. Even as late as the middle of the nineteenth century accident and not science was regarded as the fountain-head of invention, and the view that a knowledge of the causes and secret motions of things would lead to "the enlarging of the bounds of human empire to the effecting of all things possible" was scouted as the idle dream of a doctrinaire. In the year 1896 three important advances were[Pg 233] made in man's mastery of his environment. These are associated with the names of Marconi, Becquerel, and Langley. It was in this year that the last-named, long known to the scientific world for his discoveries in solar physics, demonstrated in the judgment of competent witnesses the practicability of mechanical flight. This was the result of nine years' experimentation. It was followed by several more years of fruitful investigation, leading to that ultimate triumph which it was given to Samuel Pierpont Langley to see only with the eye of faith. The English language has need of a new word ("plane") to signify the floating of a bird upon the wing with slight, or no, apparent motion of the wings (planer, schweben). To hover has other connotations, while to soar is properly to fly upward, and not to hang poised upon the air. The miracle of a bird's flight, that steady and almost effortless motion, had interested Langley intensely—as had also the sun's radiation—from the years of his childhood. The phenomenon (the way of an eagle in the air) has always, indeed, fascinated the human imagination and at the same time baffled the comprehension. The skater on smooth ice, the ship riding at sea, or even the fish floating in water, offers only an incomplete analogy; for the fish has approximately the same weight as the water it displaces, while a turkey buzzard of two or three pounds' weight will circle by the half-hour on motionless wing upheld only by the thin medium of the air. In 1887, prior to his removal to Washington as Secretary of the Smithsonian Institution, Langley began his experiments in aerodynamics at the old[Pg 234] observatory in Allegheny—now a part of the city of Pittsburgh. His chief apparatus was a whirling table, sixty feet in diameter, and with an outside speed of seventy miles an hour. This was at first driven by a gas engine,—ironically named "Automatic,"—for which a steam engine was substituted in the following year. By means of the whirling table and a resistance-gauge (dynamometer chronograph) Langley studied the effect of the air on planes of varying lengths and breadths, set at varying angles, and borne horizontally at different velocities. At times he substituted stuffed birds for the metal planes, on the action of which under air pressure his scientific deductions were based. In 1891 he published the results of his experiments. These proved—in opposition to the teaching of some very distinguished scientists—that the force required to sustain inclined planes in horizontal locomotion through the air diminishes with increased velocity (at least within the limits of the experiment). Here a marked contrast is shown between aerial locomotion on the one hand, and land and water locomotion on the other; "whereas in land or marine transport increased speed is maintained only by a disproportionate expenditure of power, within the limits of experiment in such aerial horizontal transport, the higher speeds are more economical of power than the lower ones." Again, the experiments demonstrated that the force necessary to maintain at high velocity an apparatus consisting of planes and motors could be produced by means already available. It was found, for example, that one horse-power rightly applied is sufficient to maintain a plane of two hundred pounds in[Pg 235] horizontal flight at a rate of about forty-five miles an hour. Langley had in fact furnished experimental proof that the aerial locomotion of bodies many times heavier than air was possible. He reserved for further experimentation the question of aerodromics, the form, ascent, maintenance in horizontal position, and descent of an aerodrome (ἀεροδρόμος, traversing the air), as he called the prospective flying machine. He believed, however, that the time had come for seriously considering these things, and intelligent physicists, who before the publication of Langley's experiments had regarded all plans of aerial navigation as utopian, soon came to share his belief. According to Octave Chanute there was in Europe in 1889 utter disagreement and confusion in reference to fundamental questions of aerodynamics. He thought Langley had given firm ground to stand upon concerning air resistances and reactions, and that the beginning of the solution of the problem of aerial navigation would date from the American scientist's experiments in aerodynamics. Very early in his investigations Langley thought he received through watching the anemometer a clue to the mystery of flight. Observations, begun at Pittsburgh in 1887 and continued at Washington in 1893, convinced him that the course of the wind is "a series of complex and little-known phenomena," and that a wind to which we may assign a mean velocity of twenty or thirty miles an hour, even disregarding the question of strata and currents, is far from being a mere mass movement, and consists of pulsations varying both in rate and direction from second to second. If this complexity is revealed by the stationary[Pg 236] anemometer—which may register a momentary calm in the midst of a gale—how great a diversity of pressure must exist in a large extent of atmosphere. This internal work of the wind will lift the soaring bird at times to higher levels, from which without special movement of the wings it may descend in the very face of the wind's general course. From the beginning, however, of his experiments Langley had sought to devise a successful flying machine. In 1887 and the following years he constructed about forty rubber-driven models, all of which were submitted to trial and modification. From these tests he felt that he learned much about the conditions of flight in free air which could not be learned from the more definitely controlled tests with simple planes on the whirling table. His essential object was, of course, to reduce the principles of equilibrium to practice. Besides different forms and sizes he tried various materials of construction, and ultimately various means of propulsion. Before he could test his larger steam-driven models, made for the most part of steel and weighing about one thousand times as much as the air displaced, Langley spent many months contriving and constructing suitable launching apparatus. The solution of the problem of safe descent after flight he in a sense postponed, conducting his experiments from a house-boat on the Potomac, where the model might come down without serious damage. <div class="figcenter"> <ANTIMG src="images/facing236.jpg" width-obs="493" height-obs="600" alt="" /> THE FIRST SUCCESSFUL HEAVIER-THAN-AIR FLYING MACHINE A photograph taken at the moment of launching Langley's aerodrome May 6, 1896</div> It was on May 6, 1896 (the anniversary of which date is now celebrated as Langley Day), that the success was achieved which all who witnessed it considered decisive of the future of mechanical flight. The whole apparatus—steel frame, miniature steam engine, smoke stack, condensed-air chamber, gasoline tank, wooden propellers, wings—weighed about twenty-four pounds. There was developed a steam pressure of about 115 pounds, and the actual power was nearly one horse-power. At a given signal the aeroplane was released from the overhead launching apparatus on the upper deck of the house-boat. It rose steadily to an ultimate height of from seventy to a hundred feet. It circled (owing to the guys of one wing being loose) to the right, completing two circles and beginning a third as it advanced; so that the whole course had the form of a spiral. At the end of one minute and twenty seconds the propellers began to slow down owing to the exhaustion of fuel. The aeroplane descended slowly and gracefully, appearing to settle on the water. It seemed to Alexander Graham Bell that no one could witness this interesting spectacle, of a flying machine in perfect equilibrium, without being convinced that the possibility of aerial flight by mechanical means had been demonstrated. On the very day of the test he wrote to the Académie des Sciences that there had never before been constructed, so far as he knew, a heavier-than-air flying machine, or aerodrome, which could by its own power maintain itself in the air for more than a few seconds. Langley felt that he had now completed the work in this field which properly belonged to him as a scientist—"the demonstration of the practicability of mechanical flight"—and that the public might look to others for its development and commercial exploitation. Like Franklin and Davy he declined[Pg 237] [Pg 238] to take out patents, or in any way to make money from scientific discovery; and like Henry, the first Secretary of the Smithsonian Institution (to whom the early development of electro-magnetic machines was due), he preferred to be known as a scientist rather than as an inventor. Nevertheless, Langley's desire to construct a large, man-carrying aeroplane ultimately became irresistible. Just before the outbreak of the Spanish War in 1898 he felt that such a machine might be of service to his country in the event of hostilities that seemed to him imminent. The attention of President McKinley was called to the matter, and a joint commission of Army and Navy officers was appointed to make investigation of the results of Professor Langley's experiments in aerial navigation. A favorable report having been made by that body, the Board of Ordnance and Fortification recommended a grant of fifty thousand dollars to defray the expenses of further research. Langley was requested to undertake the construction of a machine which might lead to the development of an engine of war, and in December, 1898, he formally agreed to go on with the work. He hoped at first to obtain from manufacturers a gasoline engine sufficiently light and sufficiently powerful for a man-carrying machine. After several disappointments, the automobile industry being then in its infancy, he succeeded in constructing a five-cylinder gasoline motor of fifty-two horse-power and weighing only about a hundred and twenty pounds. He also constructed new launching apparatus. After tests with superposed sustaining surfaces, he adhered to the "single-tier plan." There is interesting evi[Pg 239]dence that in 1900 Langley renewed his study of the flight of soaring birds, the area of their extended wing surface in relation to weight, and the vertical distance between the center of pressure and the center of gravity in gulls and different species of buzzards. He noted among other things that the tilting of a wing was sufficient to bring about a complete change of direction. By the summer of 1903 two new machines were ready for field trials, which were undertaken from a large house-boat, especially constructed for the purpose and then moored in the mid-stream of the Potomac about forty miles below Washington. The larger of these two machines weighed seven hundred and five pounds and was designed to carry an engineer to control the motor and direct the flight. The motive power was supplied by the light and powerful gasoline engine already referred to. The smaller aeroplane was a quarter-size model of the larger one. It weighed fifty-eight pounds, had an engine of between two and a half and three horse-power, and a sustaining surface of sixty-six square feet. This smaller machine was tested August 8, 1903, the same launching apparatus being employed as with the steam-driven models of 1896. In spite of the fact that one of the mechanics failed to withdraw a certain pin at the moment of launching, and that some breakage of the apparatus consequently occurred, the aeroplane made a good start, and fulfilled the main purpose of the test by maintaining a perfect equilibrium. After moving about three hundred and fifty feet in a straight course it wheeled a quarter-circle to the right, at the same time descending[Pg 240] slightly, the engine slowing down. Then it began to rise, moving straight ahead again for three or four hundred feet, the propellers picking up their former rate. Once more the engine slackened, but, before the aeroplane reached the water, seemed to regain its normal speed. For a third time the engine slowed down, and, before it recovered, the aeroplane had touched the water. It had traversed a distance of one thousand feet in twenty-seven seconds. One of the workmen confessed that he had poured into the tank too much gasoline. This had caused an overflow into the intake pipe, which in turn interfered with the action of a valve. The larger aeroplane with the engineer Manly on board was first tested on October 7 of the same year, but the front guy post caught in the launching car and the machine plunged into the water a few feet from the house-boat. In spite of this discouraging mishap the engineers and others present felt confidence in the aeroplane's power to fly. What would to-day be regarded by an aeronaut as a slight setback seemed at that moment like a tragic failure. The fifty thousand dollars had been exhausted nearly two years previously; Professor Langley had made as full use as seemed to him advisable of the resources put at his disposal by the Smithsonian Institution; the young men of the press, for whom the supposed aberration of a great scientist furnished excellent copy, were virulent in their criticisms. Manly made one more heroic attempt under very unfavorable conditions at the close of a winter's day (December 8, 1903). Again difficulty occurred with the launching gear, the rear wings and rudder being wrecked be[Pg 241]fore the aeroplane was clear of the ways. The experiments were now definitely abandoned, and the inventor was overwhelmed by the sense of failure, and still more by the skepticism with which the public had regarded his endeavors. In 1905 an account of Langley's aeroplane appeared in the Bulletin of the Italian Aeronautical Society. Two years later this same publication in an article on a new Blériot aeroplane said: "The Blériot IV in the form of a bird ... does not appear to give good results, perhaps on account of the lack of stability, and Blériot, instead of trying some new modification which might remedy such a grave fault, laid it aside and at once began the construction of a new type, No. V, adopting purely and simply the arrangement of the American, Langley, which offers a good stability." In the summer of 1907 Blériot obtained striking results with this machine, the launching problem having been solved in the previous year—the year of Langley's death—by the use of wheels which permitted the aeroplane to get under way by running along the ground under its own driving power. The early flights with No. V were made at a few feet from the ground, and the clever French aviator could affect the direction of the machine by slightly shifting his position, and even had skill to bring it down by simply leaning forward. By the use of the steering apparatus he circled to the right or to the left with the grace of a bird on the wing. When, on July 25, 1909, Blériot crossed the English Channel in his monoplane, all the world knew that man's conquest of the air was a fait accompli. [Pg 242] About three years after Langley's death the Board of Regents of the Smithsonian Institution established the Langley Medal for investigations in aerodromics in its application to aviation. The first award went (1909) to Wilbur and Orville Wright, the second (1913) to Mr. Glenn H. Curtiss and M. Gustave Eiffel. On the occasion of the presentation of the medals of the second award—May 6, 1913—the Langley Memorial Tablet, erected in the main vestibule of the Smithsonian building, was unveiled by the scientist's old friend, Dr. John A. Brashear. In the words of the present Secretary of the Institution, the tablet represents Mr. Langley seated on a terrace where he has a clear view of the heavens, and, in a meditative mood, is observing the flight of birds, while in his mind he sees his aerodrome soaring above them. The lettering of the tablet is as follows:— SAMUEL PIERPONT LANGLEY 1834-1906 SECRETARY OF THE SMITHSONIAN INSTITUTION 1887-1906 <hr class="tb" /> DISCOVERED THE RELATIONS OF SPEED AND ANGLE OF INCLINATION TO THE LIFTING POWER OF SURFACES WHEN MOVING IN AIR <hr class="tb" /> <blockquote> "I have brought to a close the portion of the work which seemed to be especially mine, the demonstration of the practicability of mechanical flight." "The great universal highway overhead is now soon to be opened."—Langley, 1897. </blockquote> [Pg 243] A still more fitting tribute to the memory of the great inventor came two years later from a successful aviator. In the spring of 1914 Mr. Glenn H. Curtiss was invited to send apparatus to Washington for the Langley Day Celebration. He expressed the desire to put the Langley aeroplane itself in the air. The machine was taken to the Curtiss Aviation Field at Keuka Lake, New York. Langley's method of launching had been proved practical, but Curtiss finally decided to start from the water, and accordingly fitted the aeroplane with hydroaeroplane floats. In spite of the great increase in weight involved by this addition, the Langley aeroplane, under its own power plant, skimmed over the wavelets, rose from the lake, and soared gracefully in the air, maintaining its equilibrium, on May 28, 1914, over eight years after the death of its designer. When furnished with an eighty horse-power motor, more suited to its increased weight, the aerodrome planed easily over the water in more prolonged flight. In the periodical publications of June, 1914, may be read the eloquent announcement: "Langley's Folly Flies." [Pg 244] <h3>REFERENCES</h3> <div class="hanging-indent"> Alexander Graham Bell, Experiments in Mechanical Flight, Nature, May 28, 1896. Alexander Graham Bell, The Pioneer Aerial Flight, Scientific American, Supplement, Feb. 26, 1910. S. P. Langley, Experiments in Aerodynamics. S. P. Langley, The "Flying Machine," McClure's, June, 1897 (illustrated). Langley Memoir on Mechanical Flight, Smithsonian Contributions to Knowledge, vol. 27, no. 3 (illustrated). Scientific American, Jan. 13, 1912, A Memorial Honor to a Pioneer Inventor. The Smithsonian Institution 1846-1896. The History of its First Half-Century, edited by G. B. Goode. A. F. Zahm, The First Man-carrying Aeroplane capable of Sustained Free Flight, Annual Report of the Smithsonian Institution, 1914 (illustrated). </div> <hr class="chap" /> [Pg 245] <div style="break-after:column;"></div>

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