Samuel Pierpont Langley

1906, and invitations were sent to a large number of officials and friends of the late Secretary. The meeting was called to order by the Chancellor of the Institution, who presided. During this trip he acquired a good knowledge of the continental languages, especially of French.

First, in the place of an assistant at the Harvard Observatory; two years later, in a degree of professor of mathematics and the practical direction of the observatory in An-. Around 1873 he concentrated the purely scientific side of his work on the observation and study of the sun.

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In the autumn of 1886 he was invited to the position of Assistant Secretary of the Smithsonian Institution. In the invitation Professor Baird, the then Secretary, assured him that, while in his new position he would be expected to take charge of the foreign and domestic exchanges, the library and publications, the full half of his time could be. be employed, to use Professor Baird's. Plis activities on behalf of the Institution were expanded in many ways, but he evidently felt that, apart from this, his main function was to "increase knowledge" in the new department to which his special astronomical research was chiefly devoted.

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He was made a Foreign Member of the Royal Society of London, Corresponding Member of the Institute of France, Fellow of the Royal Astronomical Society of London, a. Amid these honors, won by original research, his feeling for the popularization of science persisted, and one of its expressions gives a remarkable revelation of his heart. He provided in the Museum of the Smithsonian a room containing objects in various fields of natural research, which would delight children and arouse their interest.

In these latter activities he departed somewhat from the politics of the great man who first charted a course for the Smithsonian Institution, Joseph Henry, and from his theory and practice. It was very fortunate that Henry, during the early years of the Institution, persisted in rejecting a host of projects, each attractive, but which, had they been adopted at that early period, would have launched distracting and perhaps mutually destructive policies. But when Langley showed his willingness to bring the Smithsonian into further relation with the deep feeling of Americans who feel that our capital should be made worthy of the Republic, all danger of departure from James Smithson's intentions was over.

Each of them was a strong man, even a great man, in the branch of science he chose. I particularly remember his minute and accurate knowledge of the comparative value of various authorities, and it is only justice to say that I had reason to be deeply indebted to him. It was not only that he read works of importance in the history of the period in question, from the statesmanlike judgments of Thiers to the prose poem of Thomas.

But it ascended into wider and wider spheres—into the studies of modern metaphysicians and psychologists—which accompany it.

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In his years, for he was then almost seventy years old, all this, with all his optimism, affected him deeply. It was a lack of means from the source from which he thought he had a right to receive them. He declared that his work was only in the interest of the nation, and if.

Interestingly, a judgment was passed on these later experiments by a group of thoughtful and practical students of aerodynamics who. It now remains to allude briefly to some of his personal characteristics—to his daily life as the world saw it. It cannot be claimed that among the great body of younger men devoted to science he always excited such general affection as they had bestowed on his immediate predecessor.

THE SCIENTIFIC WORK OF SAMUEL PIERPOXT EANGLEY

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It is evidently the work of one who has laboriously constructed an instrument, and by careful testing corrected its early defects, and not the work of a student who proposes a new method by theory alone. All the trains of the great Pennsylvania Railroad system ran for many years on a time furnished by him. His method of furnishing and distributing time was one of the first and one of the best that was adopted.

The dense smog of the adjacent city of Pittsburgh made stargazing difficult, and he wisely chose the sun as his subject of study. From 1874 to 1890 he was a frequent contributor to scientific journals, sending them an average of about three articles a year. His early studies regarding the structure of the sun and his artistic skills enabled him to produce the best.

His studies of the sun were first related to its structure, but later to its spectrum. It is easy to make the principle of this instrument clear even to those unacquainted with science, but difficult even for the professional physicist to realize the immense care and labor required to bring it to its final perfection. bring. Whatever our belief about the nature of a current of electricity, there is no better way to describe it.

If the two main pipes are exactly the same, there will apparently be no flow through the cross pipe; but even a slight obstruction from one will cause some of the water to flow through the cross pipe into the other pipe.

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20 to give up his active scientific work, and he accepted only on the condition that he should also continue his work at Allegheny. However, this proved impractical; but the establishment of the Astrophysical Observatory at Washington enabled him to devote a portion of his time to research. Here he encountered that difficulty which comes to almost every man who undertakes the charge of a great scientific enterprise—a difficulty which is likely to harass his successor as it did him.

It is the same with any industrial or commercial enterprise - after expenses are covered, any additional income is a clear gain. I pointed out how little of the revenue was used for "increasing knowledge among men"^—. Any attempt I make to reduce running costs is met with insurmountable obstacles." The relief came mainly from additional grants from the government and external aid, such as the Hodgkins Foundation.

Considering the liberal conditions under which the Smithsonian Institution can become a trustee, it is surprising that rich men do not have more. The establishment of the Astrophysical Observatory, as mentioned above, enabled him to continue his work, begun in Allegheny, under much more favorable conditions. His other duties, however, forced him to delegate them largely to others, and he had the good fortune to raise a corps of assistants here.

LANGLEY'S CONTRIBUTIONS TO AERIAL N.WIGA- TION

BY OCTAVE CHANUTE

Langley then engaged in the study of astrophysics at the Allegheny Observatory, Pennsylvania, and there, early in 1887, through the liberality of the late WilHam Thaw, work was begun on the construction of a steam-engine-powered rotary table of extraordinary size. This served for three years to combat aircraft and installations equipped with most in-. To avoid complexity, they were all done on flat surfaces (which he said might not be the best form of surfaces to support), but they gave physicists and researchers, perhaps for the first time, a solid base to stand on as far as long controversial issues of air resistance and reaction.

They proved (b) that on inclined surfaces the air pressures were actually normal to the surface. They refuted (c) Newton's law, that normal pressure varied as the square of the angle of incidence on inclined surfaces. They showed (d) that Duchemin's empirical formula, proposed in 1836 and ignored for fifty years, was approximately correct; that (e) the position of the center of pressure varied with the angle of inclination, and that the movements on planes follow approximately.

It results from the fact that the higher the speed, the less the angle of inclination must be to maintain a given weight and, therefore, the horizontal component of the air pressure. It is only true if the plane alone is considered, without any additions, but it leaves out of account the resistance of the head due to the various parts of a complete flying machine, such as its frame, its body, etc.

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Meanwhile, in 1893 he published his famous paper on "The Inner Workings of the Wind", based on a completely different series of experiments. He showed in this that the irregularities of the wind were much nutch greater than hitherto supposed; that they could be used as a source of power and could explain that certain species of birds soar on outstretched, unflapped wings. It is believed that further reflections and calculations convinced him that these irregularities in the wind were probably not sufficient to fully account for soaring flight.

They are no doubt used occasionally, but the main source of the power to soar and overcome the wind probably comes from the rising tendencies found in the air. He has given an account of the building of this machine, which took five years, in his 1905 paper entitled "Experiments with the Langley Aerodrome." As might have been expected, there were endless delays and mishaps, more.

BIBLIOGRAPHY OF PUBLISHED WORKS OF S. P

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The Solar Atmosphere: An Introduction to an Account of Research Made at the Allegheny Observatory. Proceedings of the American Association for the Advancement of Science, 24th meeting, Detroit, Mich., August, 187s; Salem, 1876, pp.

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The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, London, 1884, 5th series, vol.

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