469 
of Edinburgh, Session 1865 - 66 . 
a point in the constellation Hercules is 33 millions of geographical 
miles, and that we may wager 400,000 to 1 that such a motion 
exists. 
Frederick Struve was an ordinary Counsellor of State, a Com- 
mander of the Legion of Honour, and a Corresponding Member of 
the Imperial Institute of France. He died at St Petersburg, after 
a short illness, on the 23d Hovemher 1864, in the 72d year of his 
age, and was succeeded in the Direction of the Observatory of 
Pulkowa by his distinguished son, Otto William Struve, well known 
to the scientific w^orld by his writings and his astronomical labours. 
John Francis Encke, a distinguished astronomer, was born at 
Hamburg on the 23d September 1791. His father, who was 
minister of the church of St James’, in that city, sent him to the 
University of Gottingen, where he studied under the celebrated 
Gauss, who was then Professor of Mathematics, and Director of 
the Observatory. In 1813 he was enrolled for active service in 
the military force raised by the Hanseatic towns, and afterwards 
rose to the rank of lieutenant of artillery in the Prussian service. ' 
In this capacity his acquirements became known to Baron Linde- 
nau, the Director of the Observatory of Seeberg, near Gotha. 
Having become Minister of State in 1817, the Baron gave young 
Encke the entire charge of the Observatory, which he conducted 
so ably that he was made Joint-Director in 1829. Soon after this 
he was called to Berlin, where he was appointed Director of the Koyal 
Observatory, and became Secretary to the Academy of Sciences. 
During his occupation of these two observatories Encke made 
many valuable contributions to astronomy. Among the most im- 
portant were his determination of the orbit of the famous comet of 
1680, of the distance of the earth from the sun, and of the orbit 
of the comet discovered by Pons in 1818 ; for the first of which he 
obtained the prize of Cotta, adjudged to him by Gauss and Gibers. 
His solution of the problem of the Earth’s Distance from the Sun, 
by the aid of the Transits of Yenus in 1761 and 1769, was pub- 
lished in two memoirs, entitled La Distance du Soleil. In several 
papers in the Memoirs of the Academy of Berlin, between 1829 
and 1851, he demonstrated the periodicity of Pons’ comet, which 
he proved to be identical with the comets of 1786, 1795, and 
