The whole of this establishment comprehends two principal buildings, one of which constitutes the obser vatory, and the other the dwelling-house of the astro nomer-royal. The observatory is a low oblong edifice, running east and wcst, and containing four principal apartments on the ground floor. Thc most easterly room has been lately fitted up for the reception of a very fine transit circle, by Troughton, and a valuable clock by Hardy.
The next apartment is the transit room, having a double sloping roof, with sliding shutters, opening both north and south, with great ease, by means of pulleys. The transit instrument is eight feet long, having an axis of three feet, and is suspended on two stone pillars. This instrument is rendered famous in the history of astronomy, as having been used by Halley, Bradley, and Alaskelyne. It was made by Bird originally, and has been successively improved by Dollond and Troughton. The astronomical clock, in the same room, attached to a stone pillar, was made by Graham, and has been im proved by Earnshaw.
The third apartment is at present the assistant ob server's library, and place for calculation. The most westerly apartment of the whole building is the qua drant room, in which is erected a stone pier, running north and south, to which are attached two mural qua drants of eight feet each. That on the eastern face. intended to observe objects on the southern part of the meridian, was made by Bird; and tbe other, for ob serving on the northern part of the meridian, was. made by the celebrated Graham. On the western wall is sus pended the famous zenith sector, with which Bradley made the observations at Kew, that led him to the dis coveries of the aberration of light, and the nutation of the earth's axis.
To the south of the quadrant room is a small wooden building for making occasional observations in any di rection, where the usc of a simple telescope, and an ac curate knowledge of time only, are required. It is fur nished with sliding shutters on the side and roof, to view any part of the hemisphere, from the prime ver tical down to the southern horizon. It contains some good telescopes, particularly a forty-inch achromatic, with a triple object-glass, and a five feet achromatic, by Dollond ; also a six feet reflector, by Sir William IIer schel.
To the north of the observatory, and east of the house, are two small buildings, covered with hemispherical sliding domes, in each of which is an equatorial sector by Sisson, and a clock by Arnold, which are chiefly used for observing comets. The lower apartments ot the dwelling-house are occupied by the astronomer-royal, over which is a large octagonal room, which contains a great variety of astronomical instruments, with a library consisting chiefly of scarce and scientific books. On the top of the house is a camera obscura, very well si tuated for exhibiting views of many interesting objects.
In Flamsteed's time a well was sunk in the south-east corner of what now constitutes the garden, behind the observatory, for the purpose of seeing the stars in the day time, and observing the earth's annual parallax. It was a hundred feet deep, with stone stairs down to the bottom ; but it has been long arched over, as the im provements in the telescope have rendered it unneces sary for astronomical purposes.
The observations which have, in general, been made at the Royal Observatory, in later times, are universally allowed to possess an unrivalled degree of accuracy, and the fine instruments executed by the celebrated Trough ton, now in the hands of Mr. Pond, will, we confidently expect, maintain their former character. Indeed, thc number of accurate astronomical observations which have been made here are enormous. " In shot t," it may be said, with Delarnbre, " of the four volumes of observations which NIaskelyne has published, that if, by a great revolution, the sciences should be lost, and that this collection only were saved, there would be found in it materials sufficient to rear almost an entire new edi fice of modern astronomy." One cannot indeed enter this place without being impressed with a feeling of re verence for it, as a temple dedicated to the noblest and most sublime of all the sciences.
Subjoined are the names of the astronomers who have officiated here in succession : Flamstced, 43 years ; Halley, 23 years ; Bradley 20 years ; Bliss, two ycars ; and Maskelyne 46 years.