SCIENCE. 



[N. S. Vol. IX. No. 210. 



observations. The wordiug of the bill 

 which accompanied the report and became 

 a law August 31, 1842, was as follows : 



" Be it enacted by the Senate and House of Repre- 

 sentatives of the United States of America in Congress 

 assembled : That tlie Secretary of the Navy be and lie 

 is hereby authorized to contract for the building of a 

 suitable house for a depot of charts and instruments 

 of the Navy of the United States on a plan not exceed- 

 ing in cost the sum of twenty-five thousand dollars. 



"And be it further enacted : That the sum of ten 

 thousand dollars be and is hereby appropriated of any 

 money in the Treasury not otherwise appropriated 

 towards carrying this law into effect. 



"And be it further enacted: That the said estab- 

 lishment may be located on any portion of the public 

 land in the District of Columbia which the President 

 of the United States may deem suited to the purpose. ' ' 



The Secretary of the ISTavy immediately 

 placed the preparation of the plans for the 

 new observatory in the hands of Lieuten- 

 ant Gilliss, who, after consulting with as- 

 tronomers in America, visited Europe to 

 obtain the views of those competent to 

 advise in these matters. In March, 1843 

 he returned home, having ordered the 

 instruments under authority from the Sec- 

 retary of the Navy. Only eighteen months 

 were consumed in the erection of the 

 buildings, the mounting of the instruments 

 and the procuring of a library, and on the 

 7th of February, 1845, Gilliss presented a 

 detailed report of his labors (Senate Docu- 

 ment, No. 114, 28th Congress, 2d session. 

 Vol. VII.) which contains a careful de- 

 scription of the buildings and instruments, 

 illustrated by accurate drawings. The site 

 selected for the building was a reservation 

 between 23d and 25th Streets west, extend- 

 ing from E Street north to the Potomac 

 river. The area of the plot was 17.85 

 acres. The elevation of the ground on the 

 building site was about 100 feet above the 

 Potomac. Gilliss stated that the new 

 equipment was as follows : 1st, an achro- 

 matic equatorial telescope by Merz and 

 Mahler, Munich, of 9.6 inches' aperture. 

 2d, a meridian transit instrument of 6^ 



inches' aperture by Ertel, of Munich. 3d, 

 a prime vertical transit instrument of 4.9 

 inches' aperture by Pistor and Martins, 

 Berlin. 4th, a mural circle by Troughton 

 and Simms, London, with a telescope of 

 4.1 inches' aperture, and a circle 5 feet in 

 diameter divided to 5' and read by six 

 micrometer microscopes. 5th, a comet 

 seeker of 4 inches' aperture by Utzschneider 

 and Fraunhofer, Munich. 6th, magnetic 

 instruments. 7th, meteorological instru- 

 ments. 8th, books. In addition to those 

 items purchased, there belonged to the 

 ' Dej)ot of Charts and Instruments ' a port- 

 able transit and two clocks, purchased by 

 Lieutenant Wilkes for the Exploring Expe- 

 dition, and a 30-inch transit circle and two 

 clocks ordered by Gilliss for the ' Depot.' 



At the close of September, 1844, Gilliss 

 reported the observatory completed, with 

 the instruments mounted and ready for use. 

 On the 1st of October, 1844, Lieutenant M. 

 F. Maury was ordered to take charge of 

 the institution, and directed to remove to it 

 all the nautical books, charts and instru- 

 ments of the then-existing depot. 



In reviewing the history of the Naval Ob- 

 servatory during Maury's administration, 

 we shall first notice the instrumental equip- 

 ment, in the selection of which it is probable 

 that Gilliss was principally influenced by 

 English advisers. Instrumental construc- 

 tion was just then passing through a crit- 

 ical period. The Observatory of Pulkowa, 

 which was completed in 1838, following the 

 German school of construction, rejected the 

 mural circle, and supplied its place with 

 the celebrated Ertel vertical circle. An 

 Ertel transit instrument and a Repsold 

 meridian circle completed the outfit of Pul- 

 kowa for meridian work, and these instru- 

 ments were amply provided with horizontal 

 collimators and azimuth marks distant 550 

 feet, which were rendered visible by the in- 

 terposition of lenses of corresponding foca 

 length. In contrast with this, the Naval 



