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SKETCH OF PROFESSOR HENRY DRAPER

sketch of Henry Draper which appeared in a late number of "Harper's Weekly":

"He had for a companion, friend, and teacher, from childhood, one of the most thoroughly cultivated and original scientific men of the present age, who attended carefully to his instruction, and impressed upon him deeply the bent of his own mind in the direction of science. The boy was, in fact, immersed in science from his youngest years, and not merely crammed with its results, but saturated with its true spirit at the most impressible period. He was taught to love science for the interest of its inquiries, and was early put upon the line of original investigation in which he has won his celebrity. Henry Draper inherited not only his father's genius, but his problems of research. Dr. John W. Draper was an experimental investigator of such fertility of resources and such consummate skill that the European savants always deplored his proclivity to literary labors as a great loss to the scientific world. Henry Draper inherited from his father in an eminent degree the aptitude for delicate experimenting, and a fine capacity of manipulatory tact. The elder Draper was one of the founders of the recent science of photo-chemistry. He worked early and brilliantly in the new and fascinating field of the chemistry of light, and more than forty years ago by his extensive contributions to this subject he prepared the way for those who entered to reap the fruits of his labors in the splendid field of spectrum analysis. But the scepter was not to depart from the family. Henry pursued the same line of research, and by his extension of it will have a permanent place among the discoverers of the period."

Henry Draper's first important scientific investigation was made at the age of twenty, and was embodied in his graduating thesis at the Medical College. It was on the functions of the spleen, which was illustrated by microscopic photography—an art then in its infancy. Soon after receiving his degree he went to Europe, and while there visited the widely-known observatory of Lord Rosse, and studied the construction and working of his celebrated colossal reflecting telescope. This led him to consider the problem of using reflecting telescopes for the purpose of photographing celestial objects. On his return home he constructed a telescope of this kind of fifteen and a half inches aperture, and with it took a photograph of the moon fifty inches in diameter—the largest ever made. His success spurred him on to further improvements, so that he became an adept in grinding, polishing, and testing reflecting mirrors. An equatorial telescope was afterward constructed by him, with an aperture of twenty-eight inches, for his observatory at Hastings-on-the-Hudson. The instrument was wholly the work of his own hands, and was designed mainly to photograph the spectra of the stars. After a long series of experiments, it was finished in 1872, and has been pronounced by President Barnard as 'probably the most difficult and costly experiment in celes-