ASTRONOMICAL OBSERVATORIES. 225 



On his return from Europe, in 1840, Professor Bartlett\ 

 made a report to the Engineer Department at Washing- 

 ton on the observatories of Europe. In this report he 

 embodied the modern improvements in the construction 

 of instruments, as -well as the erection of observatories. 

 He afterward prepared a plan and estimates for an ob- 

 servatory at Washington, for Mr. Poinsett, then Secretary 

 of War. 



In 1842 was passed an Act of Congress authorizing the 

 erection of a depot of charts and instruments for the navy, 

 the expense being limited to $25,000. Lieutenant Gilliss 

 was instructed by the Secretary of the Navy to present a 

 plan of a building, after consultation with the principal 

 astronomers of the United States. The plan thus pre- 

 pared was afterward submitted to the most eminent as- 

 tronomers of Europe, and the model finally adopted em- 

 braced such improvements as they had recommended. 

 The observatory consists of a central building of brick, 

 with wings upon the east, west, and south sides. The 

 central building is 50 feet square, two stories high, with 

 a basement, and is surmounted by a revolving dome 23 

 feet in diameter, with an elevation of 18 feet from the 

 floor. Directly under the dome is the great pier, whose 

 diameter at the base is 15 feet, and tapers gradually to 

 the top, upon which rests the great equatorial. The cen- 

 tral building, except the dome, is employed exclusively 

 for official purposes. The west wing is 21 by 26 feet, 

 and 18 feet high, and is appropriated to the meridian 

 transit instrument. The east wing is 48 by 21 feet, and 



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