It stands a mile from the Capitol, in the city of Albany, upon the crest of a hill, so difficult of approach, as to be in reality a Hill of Science. There are two ways of getting to it. In both cases there are rail fences to be clambered over, and long grass to wade through, settlements to explore, and a clayey road to travel; but these are minor troubles. The elevation of the hill above tide-water is, perhaps, 200 feet; its distance from the Capitol about a mile and a half. The view for miles is unimpeded; and the Observatory is belted about with woods and verdant lawns. There could not be a finer location or a purer air. The plateau contains some fifteen acres. The Observatory is constructed in the form of a Latin cross. Its eastern arm is an apartment 22 by 24 feet, in which the meridian circle is to be placed. The western arm is a room of the same dimensions, intended for the transit instrument. From the north and south faces of both rooms are semi-circular apsides, projecting 6 feet 6 inches, containing the Collimator piers and the vertical openings for observation. The entire length of each room is, therefore, 37 feet. In the northern arm are placed the library, 23 feet by 27 feet; two computing rooms, 12 feet by 23 feet each; side entrance halls, staircases, &c. The southern arm contains the principal entrance, consisting of an arched colonnade of four Tuscan columns, surrounded by a pediment. A broad flight of stone steps leads to this colonnade; and through the entrance door beneath it to the main central hall, 28 feet square, in which are placed (in niches) the very beautiful electric clock and pendulum presented by Erastus Corning, Esq. The center of this hall is occupied by a massive pier of stone, 10 feet square, passing from the basement into the dome above, and intended for the support of the great heliometer. Directly opposite the entrance door is a large niche, in which it is proposed to place the bust of the late Mr. Dudley. Immediately above this hall is the equatorial room, a circular apartment, 22 feet 6 inches in diameter, and 24 feet high, covered by a low conical roof, in which and in the walls are the usual observing slits. The drum, or cylindrical portion, of this room is divided into two parts--the lower one fixed, the upper, revolving on cast-iron balls moving in grooved metal plates, can command the entire horizon.