_Brilliancy._—Her brightness is such as to lead her to occasionally become a conspicuous object to the naked eye in daytime, and at night she casts a perceptible shadow. This is specially the case near the epoch of her maximum brilliancy, which is attained when the planet is in a crescent form, with an apparent diameter of about 40″, and situated some 5 weeks from inferior conjunction. Though only a fourth part of the disk is then illuminated, it emits more lustre than a greater phase, because the latter occurs at a wider distance from the Earth and when the diameter is much less. Her appearance is sometimes so striking that it is not to be wondered at that people, not well informed as to celestial events, have attributed it to causes of unusual nature. When the planet was visible as a morning star in the autumn of 1887, an idea became prevalent in the popular mind that the “Star of Bethlehem” had returned, and there were many persons who submitted to the inconvenience of rising before daylight to gaze upon a spectacle of such phenomenal import. And they were not disappointed in the expectancy of beholding a star of extreme beauty, though altogether wrong in surrounding it with a halo of mystery and wonder. At intervals of eight years the elongations of Venus are repeated on nearly the same dates as before, and the planet is presented under very similar conditions. This is because five synodical periods (nearly = 13 sidereal periods) of Venus are equal to eight terrestrial years. Thus very favourable E. elongations occurred on May 9, 1860, May 7, 1868, May 5, 1876, and May 2, 1884; and on April 30, 1892, there will be a similar elongation. _Period &c._—Venus moves round the Sun in an orbit of slight eccentricity, and completes a revolution in 224^d 16^h 49^m 8^s. Her mean distance from that luminary is 67,000,000 miles. The apparent diameter of the planet varies from 9″·5 at superior to 65″ at inferior conjunction, and it averages 25″ at elongations. Her real diameter is 7500 miles. The polar compression is very slight—in fact, not sufficiently decided for measurement; this is also true of Mercury.