astronomical tables would be equally perfect; and Delambre, when delivering an _éloge_ on Maskelyne before the Institute of France, remarked, that if by some grand revolution in the moral or physical world, the whole of the monuments of existing science should be swept away, leaving only the Greenwich observations and some methods of computation, it would be possible to reconstruct from these materials the entire edifice of modern astronomy. A few years ago it was resolved by the Lords of the Admiralty, that the time should be shown at Greenwich once in every day of the year. This is done by means of a large black ball which surmounts the north-western turret of the observatory. The ball, seen in the vignette, is elevated by machinery to the index, showing the four cardinal points; and, the instant it begins to descend, marks the mean solar time to be 1 P.M. Being plainly observable from the Thames, the arrangement affords a convenient opportunity for seamen to regulate their chronometers and clocks. [Illustration: =Greenwich Observatory.=] The fame of Flamstead, the first astronomer royal, does not rest upon any brilliant discovery, but upon an enlightened view of the importance of accurate observation, and the unwearied zeal and industry with which he pursued it. A better representation of him cannot be given than by supposing Tycho Brahe in possession of a telescope, and the adaptation of it to other instruments. Laplace calls him “one of the greatest observers that has ever appeared,” and Delambre remarks, “his name will be eternally cited like those of Hipparchus and Tycho, both of whom, as an observer, he surpassed.” Born in the neighborhood of Derby, and brought up in limited circumstances in that town, he wrought his way to a station at the head of practical astronomy, and established a continental reputation by dint of strong natural genius and unremitting application, in the face of great discouragements. Bad health was a frequent attendant upon him all his days. The patronage of the crown did not screen him from the want of adequate resources, while from several of his scientific contemporaries he encountered dishonorable treatment. The salary attached to his office, then a hundred a year, was often in arrears. Instruments were promised him by the government, but he had to find his own, commencing his duties in 1676 with an iron sextant of seven feet radius, two clocks, and a quadrant of three feet radius, with two telescopes, which he brought with him from Derby. With these instruments he could only measure the relative positions of the stars, and it was not until 1689 that he succeeded in constructing at his own expense a mural arc to determine their absolute places. From this period, through an interval of thirty years, his time was spent in valuable labors, the fruit of which appears in the formation of a catalogue of three thousand stars, and a vast collection of lunar and