| SKETCH OF PROFESSOR OTTO WILHELM STRUVE. |
By Professor SIMON NEWCOMB.
OTTO WILHELM STRUVE, now Director of the Pulkowa Observatory, was born at Dorpat, Russia, May 7, 1819. His father was Dr. Wilhelm Struve, Director of the Dorpat Observatory, and one of the most distinguished of European astronomers. While the son Otto was still a youth, the father imbued the Emperor Nicholas, whose confidence he enjoyed in a high degree, with the notion of erecting the greatest observatory in the world, and thus adding to the luster of his reign and associating his name with the history of science. Thus arose the great Observatory of Pulkowa, some twelve miles south of St. Petersburg, which has sometimes been called the astronomical capital of the world. The work of erecting the observatory, constructing the instruments, and getting the whole established and at work, occupied the years from 1835 to 1840. On the removal of the family to the new establishment, Otto, although only a little over twenty years of age, commenced work as an assistant to his father. His first serious work was an examination of all the stars in the northern heavens, made with the great refractor, in order to detect new double stars. The result was a catalogue of many hundred double stars, all before unknown, and many very close and difficult. The subject of double stars was one which seemed to belong especially to the Struve family, their observations and measurements having been at Dorpat the great work of the father, who thus became preeminent in this branch of research. His "Mensuræ Micrometricæ" is one of the standard astronomical works of the century, a book whose magnificent proportions correspond to the labor expended in its preparation. The next considerable work of the son, and one which has been of enduring value, was a determination of the constant of precession, or, to speak more popularly, of the annual amount of motion of the equinox among the stars. His result has been the accepted standard for thirty years, and the work won the gold medal of the Royal Astronomical Society in 1850.
In 1847 and 1848 he made a series of observations of the satellites of Uranus and Neptune with the great equatorial. His observations of the satellites of Neptune gave the first mass of that planet, which was received with much confidence, but the very unfavorable situation of the planet rendered the result more erroneous than was at first supposed. It has since been proved that the observations made about the same time by Bond, at the Harvard Observatory, gave a result much nearer the truth. While on this work he commenced a search for the inner satellites of Uranus, which had been suspected by Sir William Herschel, but have since been proved not to exist. He succeeded, however, in making several observations of what he at the time supposed to be a new inner satellite, but did not succeed in getting a suf-
