OCCULTATIONS.

Elements for facilitating the Calculation of Occultations which may be visible in the United States in 1851.

Visible in the United States, Mean Time, Washington Observatory.

A Table showing the Illuminated Portions of the Disks of Venus and Mars.

THE numbers in this table are the versed sines of that portion of the disks which, to an observer on the Earth, will appear to be illuminated, the apparent diameters of the planets at the time being considered as unity.

To a spectator on the Earth, Venus appears most brilliant when her elongation is about 40°, and she is approaching her inferior conjunction, or receding from it; in the latter of which positions she will be on the 21st of January. Mars is most brilliant about the time of his opposition to the Sun,

being then also nearest the Earth; in which position he will not be this

Position and Magnitude of the Rings of Saturn, according to Bessel and Struve, for every Fortieth Day in the Year, at 7 hours in the Morning.

a denotes the outer semi-transverse axis of the outer ring.

"outer semi-conjugate axis of the outer ring, positive when the
northern surface is visible, negative when the southern.
"inclination of the northern semi-conjugate axes of the rings
to the circle of declination; when East, when West.
angle of elevation of the Earth above the plane of the rings,
as seen from Saturn; + when North, when South.
angle of elevation of the Sun above the plane of the rings, as
seen from Saturn; + when North, when South.

The inner semi-transverse axis of the inner ring is two thirds of a, diminished by 0.07. The inner semi-conjugate axis of the inner ring is two thirds of b.

The Opposition will take place on the 24th of October.