Leaving the Ball Turret, and the old building which it surmounts, the new Observatory, where the chief work of the establishment is done, claims our notice. This attention would scarcely be given to its outward appearance for it is a long low building, scarcely seen beyond its own boundaries. The Greenwich Observatory is not a _show_ place, but an eminently practical establishment. St. Petersburg and other cities have much more gorgeous buildings devoted to astronomical purposes, and Russia and other countries spend much more money on astronomy than England does, yet the Greenwich Tables have a world-wide reputation, and some of them are used as the groundwork for calculations in all Observatories at home and abroad. The astronomer does not want marble halls or grand saloons for his work. Galileo used a bell-tower at Venice, and Kepler stood on the bridge at Prague to watch the stars. The men, not the buildings, do the work. No disappointment need be felt, then, to find the modern Observatory a range of unadorned buildings running east and west, with slits in the roof, and in some of the walls. Within these simple buildings are the instruments now used, displaying almost the perfection of mechanical skill in their construction and finish—beautifully adapted to the object they have to fulfil, and in perfect order. They are fixed on solid piers of masonry, deeply imbedded in the earth, to secure freedom from vibration—a quality better obtained when the foundations are on sand or gravel than when on rock. To describe the instruments by their technical names, and to go into any particulars of the instruments they have superseded, would take space, only to do the work of a scientific treatise. Enough, therefore, to say that there are the telescopes best adapted to the chief duty of the place, which is, watching the moon whenever she is visible; watching the _clock-stars_, by which the true time is calculated more exactly than it could be from observations of the sun alone; and watching other planetary bodies as they pass the meridian. Eclipses, occultations, and other phenomena, of course, have their share of attention, and add to the burden of the observer’s duties.