470 Proceedings of the Royal Society 
1805. This interesting body, now known as Encke’s Comet, 
moves in an elliptical orbit within that of Jupiter, and completes 
its revolution in three years and four mouths. Having found 
that from 1786 to 1795 the time of its revolution had diminished 
from 1208*11 days to 1207*88, and between 1795 and 1805 from 
1207*88 to 1207*42 days, he concluded that the diminution was pro- 
duced by the action of Jupiter ; but upon using a more correct 
value of the mass of that planet, he found that the difference be- 
tween the observed and computed places of the comet could be 
accounted for only on the hypothesis of a resisting medium — a 
doctrine which, in its astronomical relations, must remain in 
abeyance, till it is exhibited in the motions of other celestial 
bodies. 
Upon his removal to Berlin, Encke became editor of the Astro- 
nomisches Jahrbuch, which contains many of his papers on physical 
astronomy. He visited Scotland in 1839, and took an active part 
in the proceedings of the British Association which met at Grlas- 
gow. He was a member of many foreign academies, and a Cor- 
responding Member of the Imperial Institute of France. He died 
at Berlin in 1865, in the seventy-fifth year of his age. 
Sir John Eichardson, the distinguished Arctic traveller and 
navigator, was born at Dumfries in 1787, and was educated at the 
grammar school of that town. He entered the University of Edin- 
burgh in 1801, with the view of following the medical profession. 
After obtaining the diploma of the Eoyal College of Surgeons, he was 
appointed assistant-surgeon to the Nymphe, one of Sir Eichard 
Keats’ squadron, which accompanied Lord Grambier to the bombard- 
ment of Copenhagen. In 1807 the Nymphe was employed in the 
blockade of the Tagus ; and Mr Eichardson was present, as a 
volunteer, in two unsuccessful attempts to cut out vessels anchored 
higher up the river. After serving in different ships in various parts 
of the world, he returned to Edinburgh to pursue his medical studies; 
and in 1817 he took the degree of doctor of medicine. In 1819 
he was appointed surgeon and naturalist to the expedition under 
Lieutenant Franklin, which was sent to survey the northern coast 
of North America. He returned to England in 1822, and in 1824 
he was appointed surgeon to the royal marines at Chatham, In 
