In the death of Dr. S. P. Langley, secretary of the Smithsonian Institution, America loses one of its most eminent men of science. Langley was born in Roxbury, Mass., on August 22, 1834, descended from long lines of New England ancestry. As a boy he was interested in astronomy, radiant energy and mechanical flight, and with his brother, now Professor John W. Langley of the Case School of Applied Science, he constructed telescopes. He did not enjoy or suffer a college education, but practised civil engineering and architecture, until, at the age of thirty-one, he became assistant in the Harvard Observatory. In 1866 he went to the U. S. Naval Academy as assistant professor of mathematics, and the following year was made director of the Allegheny Observatory and professor of astronomy and physics in the Western University of Pennsylvania. In 1887 he was appointed assistant secretary of the Smithsonian Institution and succeeded to the secretaryship on the death of Baird the same year. This was then, as it is perhaps still, the most responsible position and the highest honor that can be conferred in this country on a man of science.
Langley made his first published contribution to science at the age of thirty-five, it being a report on the total eclipse of August 7, 1869, observed in Kentucky. In the following year he again observed a solar eclipse, making observations on the coronal rays, and this was followed by his important researches on the solar photosphere. His work on the radiant energy of the sun resulted in and was promoted by the invention of the bolometer, an instrument which has been perfected to measure a millionth of a degree of temperature. This is accomplished by changes of electrical resistance due to heat and detected by a galvanometer, whose fluctuations may be photographed. Some of Langley's most important observations were obtained in 1881 on Mount Whitney at an elevation of 14,000 feet, and they have been continued to the present time in the Astrophysical Observatory, which was in 1891 established in connection with the Smithsonian Institution. Probably Langley's greatest work is connected with the heat of the sun and the infrared rays of the spectrum, but perhaps his researches on aerodynamics are equally well known. His theoretical and experimental contributions to this subject are of fundamental importance, in no wise lessened by the fact that he was unable to solve the practical problem of aerial flight.
Langley died from a stroke of paralysis on February 27. A sketch of his life by Dr. E. S. Holden with a portrait was published in Volume XXVII. of this journal. The frontispiece to the present issue shows Dr. Langley in the robes in which he received the D.C.L, degree from Oxford University. The regents of the Smithsonian Institution have passed the following memorial resolution:
That in the death of Mr. Langley this Institution has lost a distinguished, efficient and faithful executive officer, under whose administration the international influence of the parent institution has been greatly increased, and by whose personal efforts two important branches of work have been added to its care—the National Zoological Park and the Astrophysical Observatory.