The part of the Observatory so conspicuous from without is the portion least used within. When it was designed by Christopher Wren, the general belief was that such buildings should be lofty, that the observer might be raised towards the heavenly bodies whose motions he was to watch. More modern science has taught its disciples better; and in Greenwich,—which is an eminently practical Observatory,—the working part of the building is found crouching behind the loftier towers. These are now occupied as subsidiary to the modern practical building. The ground floor is used as a residence by the chief astronomer; above is the large hall originally built to contain huge moveable telescopes and quadrants—such as are not now employed. Now-a-days, this hall occasionally becomes a sort of scientific counting-house—irreverent but descriptive term—in which, from time to time, a band of scientific clerks are congregated to post up the books, in which the daily business of the planets has been jotted down by the astronomers who watch those marvellous bodies. Another portion is a kind of museum of astronomical curiosities. Flamstead and Halley, and their immediate successors, worked in these towers, and here still rest some of the old, rude tools with which their discoveries were completed, and their reputation, and the reputation of Greenwich, were established. As time has gone on, astronomers and opticians have invented new and more perfect and more luxurious instruments. Greater accuracy is thus obtainable, at a less expenditure of human patience and labour; and so the old tools are cast aside. One of them belonged to Halley, and was put up by him a hundred and thirty years ago; another is an old brazen quadrant, with which many valuable observations were made in by-gone times; and another, an old iron quadrant, still fixed in the stone pier to which it was first attached. Some of the huge telescopes that once found place in this old Observatory, have been sent away. One went to the Cape of Good Hope, and has been useful there. Another of the unsatisfactory, and now unused, instruments had a tube twenty-five feet long, whose cool and dark interior was so pleasant to the spiders that, do what they would, the astronomers could not altogether banish the persevering insects from it. Spin they would; and, spite of dusting and cleaning, and spider-killing, spin they did; and, at length, the savans got more instruments and less patience, and the spiders were left in quiet possession. This has been pleasantly spoken of as an instance of poetical justice. It is but fair that spiders should, at times, have the best of astronomers, for astronomers rob spiders for the completion of their choicest instruments. No fabric of human construction is fine enough to strain across the eye-piece of an important telescope, and opticians preserve a particular race of spiders, that their webs may be taken for that purpose.