200 A CENTURY'S PROGRESS IN ASTRONOMY. 



about sixty years. Contemporary with John 

 Herschel was his great rival in double - star 

 astronomy, Friedrich Georg Wilhelm Struve. 

 Born at Altona in 1793, Struve took his degree 

 in 1811 at the Russian University of Dorpat. 

 In 1813 he became director of the Dorpat 

 Observatory, and was in 1839 promoted to 

 Pulkowa, as director of the great Observatory 

 there, remaining at its head until within three 

 years of his death, on November 23, 1864. 

 Struve's first recorded observation was on the 

 double star Castor. In 1819 he commenced to 

 measure the position-angles of double stars, of 

 which he published a catalogue of 795. In 

 1825 he commenced a review of the heavens 

 down to fifteen degrees south, and thus dis- 

 covered 2200 previously unknown objects. The 

 results were published in Struve's ' Mensurae 

 Merometricae,' which appeared in 1836, giving 

 the places, distances, colours, position - angles, 

 and relative brilliance of 3112 double and mul- 

 tiple stars. 



Struve's successor in this branch of astronomy 

 was his son, Otto Wilhelm von Struve, born in 

 1819 at Dorpat, who became in 1837 assistant 

 to his father, and in 1861 succeeded him as 

 director of the Pulkowa Observatory. In 1890 

 he retired from this post, settling in Germany, 



