102 SCIENCE. [1899.
exists a residue of atmosphere which may yet be detected ; that there is no surface liquid and no sign of erosion by water ; and that there is no coating of ice in sight, not even at the poles, although some may exist in the circumpolar depressions.
Messrs. Lowell and Drew confirm Schiaparelli's observation that Mercury rotates once during his revolution round the sun, and they record the appearance of lines and dark patches on the planet's disc. The yellowish colour of Venus they ascribe to an atmosphere, and they consider that she always presents to the sun the same aspect. Mars was found in possession of a number of new canals and lakes. The white South Polar cap was observed to diminish as the equinox approached. At the same time a dark line formed round it, and the grey tint of the south temperate zone assumed a distinct bluish green, suggestive of a growing vegetation. Later this colour changed through brown to a slowly brightening yellow. The projections often seen on the terminator of this planet are due, in Professor Pickering's opinion, to clouds in the Martian atmosphere. He had already suggested that the orb's mean temperature was high, and such a fact would help to explain the dis- appearance of cloud during the orb's day. The value of Mars' period of rotation is given by Professor Bakhuyzen as 24h. 37m. 22*66s. ± 0-01328- Mr. Denning puts it at 24h. 37m. 2270s.
Vesta was found to have a polar compression of T V, the major diameter being almost in the direction of its orbit. Its rotation was completed in less than thirty hours.
Herr Fauth has observed on several occasions a brilliant white spot, about 4" in diameter, on the north-eastern belt of Jupiter. The great red spot has become somewhat faint. Its motion, which had been accelerated, fell off to the extent of l a 4s. ; but this change was irregular. Mr. Denning has recorded many markings moving at different rates. The quickest was a small dark spot in longitude 145°, which had a period about twenty-seven seconds less than that of the great red spot. The period of rotation of Satellite I. is 12h. 24m., and its orbital ellipticity is found to be greater than in 1892. Professor Barnard reports the periodic time of Satellite V. to be llh. 57m. 22«647s.
On March 18 Professor Pickering discovered by the photographic method that Saturn has a ninth satellite, which he has named Phoebe. Its period of revolution is about seventeen months, and so it must be the outermost of its companions. Its distance from Saturn may be about 7,500,000 miles, and its diameter may be between 100 and 200 miles.
A spectroscopic examination of Saturn's rings has led Professor Hale to confirm the general opinion that they possess no atmosphere.
Dr. Witt, exercising a discovers right, has named the new planet Eros, thus rejecting Professor Chandler's proposal to call it Pluto. An examination of photographs taken during 1893-6 shows that on a large proportion of the plates the planet had left traces. Its eccentricity is extreme, On approaching the sun it traverses in 322 days a distance of 61,000,000 miles, or 200,000 miles a day.
The chief comets of the year were Brooks and Chase left over from 1898, a new one, discovered March 3 by Professor Swift, Tuttle in March,
