All obstacles to further progress being happily overcome, plans for erecting a Naval Observatory under the best available conditions were speedily made matter for diligent study. Visits were made to the Northern cities to obtain assistance, distinguished astronomers were consulted, and an accomplished architect secured to draught plans, the whole care being intrusted to Lieutenant Gilliss. The locality chosen for the observatory possesses an historic interest. The site assigned to it was known as "Reservation No. 4," on the original plan of the city. It lies on the north bank of the Potomac, in the southwestern part of the city. When General Braddock marched against Fort Duquesne in the colonial wars, his troops landed and encamped on this hill. Washington's letters show that he crossed at this point from Alexandria to join Braddock at Frederick. A large rock within the grounds of the observatory is pointed out as the spot on which these landings were made. It was here that the first President proposed to locate a national university, and at a later date it was suggested by President John Quincy Adams for the site of an observatory. The base of the observatory is the second highest eminence within the city limits, and is on a level with the floor of the Congressional Library.
In 1843 Lieutenant Gilliss reported to the Navy Department the adoption of a plan for an observatory, and also the progress of the erection of a building in accordance with the plan. In 1844 the new building was ready for occupancy, and the instruments adjusted for the commencement of active work. The central building is about fifty feet square, raised on a firm foundation, and built of brick in the most thorough manner. It is two stories and a basement high, with a parapet and balustrade of wood around the top, and is surmounted by a revolving dome resting on a circular wall. The roof is nearly flat, and so arranged as to form a level promenade for gazing observations. On the east and west sides of the building are wings, and also on the south. In 1870, an observing-room for the transit-circle was added, forming an extension of the west wing. A tower and dome, to accommodate the superb new equatorial telescope recently completed, was finished in October. The equipment of the observatory in astronomical, magnetic, and meteorological instruments is now in a fair way to become worthy of the institution and the country it represents, and the library is increasing rapidly in the number of volumes and their scientific value.
Among the influences that helped to bring about this auspicious result were, in the first place, the unswerving interest and indefatigable zeal of Mr. John Quincy Adams. Although his suggestions concerning the establishment of a national observatory were treated with neglect during the term of his presidency, he did not lessen his efforts in the cause dear to his heart. In 1838 he presented its claims before President Van Buren, and in 1842 in his place in the House of
