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SCIENTIFIC SUMMARY. 
ASTRONOMY. 
Gold Medal of the Royal Astronomical Society. — At the General Meeting 
•of the Royal Astronomical Society, on February 11, the gold medal was 
presented to M. Delaunay, for his researches into the problem of the moon’s 
motion. 
The Imperial Observatory at Paris. — The same astronomer, well known 
as a skilful mathematician, has been appointed to the management of 
the Paris Observatory, in the place of M. Leverrier. The latter had given 
offence to his colleagues by the brusqueness of his demeanour and the 
■difficulties which he threw in the way of independent scientific research. 
Loewy, Wolf, Marie Davy, and Villarceau, astronomes adjoints, drew up a 
memorial, which was signed by all their subordinates, in which they addressed 
the Minister of the Interior, pointing out the defects in the superintendence 
of the Observatory, and laying stress on special grievances to which they 
had been subjected. They submitted to him the choice of dismissing 
Leverrier or accepting their resignations. lie adopted the former alterna- 
tive. If Delaunay is a less distinguished astronomer than Leverrier, as cannot 
indeed be questioned, it is yet certain that under his superintendence better 
work will be done at the Paris Observatory. All astronomers will, how- 
ever regret that the name of Leverrier, which has outshone all but a few 
in the galaxy of astronomical fame, should thus be temporarily clouded. 
Doubtless by fresh claims to the admiration of the scientific world he will, 
before long, rise stronger from his fall. 
Colour Changes in the Planet Jupiter. — We have mentioned, that last 
October Mr. Drowning noticed that the great equatorial belt of Jupiter, 
usually the brightest part of the planet’s disc, was of a greenish-yellow tint, 
resembling the colour known among artists as yellow-lake. Since then the 
belt has passed through other changes, appearing sometimes of an almost 
full orange-yellow, at others coppery-red, while its boundaries both on the 
north and south have exhibited the most surprising changes of figure. 
A etc Micrometer for Measuring the Position of Lines in Faint Spectra . — 
Mr. Drowning has contrived a bright-cross micrometer, by which the lines 
in faint spectra may be very conveniently measured. A small tube attached 
to the side of the star-spectroscope has at its outer part a glass plate, black- 
ened, with two fine cross-lines across the centre. A lens produces an image 
of the bright cross in the field of view, by reflection at the nearest face of 
