734 



SCIENCE 



[N. S. Vol. XXX. No. 777 



of its relative size and position witli regard to the 

 other planets, to the sixth or seventh satellite of 

 Jupiter. The inclinations of the orbits of these 

 two bodies are 28° and 26°, respectively. The 

 region already covered in the photographic search 

 extends along the ecliptic for 25°, and reaches to 

 a maximum distance of 10° to the north and 

 south of it. It is expected therefore to make an 

 examination of the higher latitudes next year. 

 The number of stars already examined in the 

 search is estimated at about 300,000. 



The Spectrum of a Meteor: Williamina P. 



Fleming. 



On August 14, 1909, while examining a ship- 

 ment of plates recently received from Arequipa 

 the spectrum of a meteor was found on a photo- 

 graph taken with the Bruce 24-inch telescope on 

 May 18, 1909. This must have been an unusually 

 bright object, since its trail is very intense, con- 

 sisting of twenty-three bright lines or bands. As 

 the photograph has so recently been received at 

 Cambridge no study of the spectrum has as yet 

 been attempted. 



Graduation Errors of the Circles of the Six-inch 

 Transit Circle of the U. S. Naval Observatory : 

 J. 0. Hammond. 



This consisted of a description of the methods 

 and results of a thorough examination of the 

 circles that is still in progress. The circles were 

 graduated by the Warner and Swasey Company, 

 of Cleveland, and seem to be quite as accurate 

 as those of the best foreign makers. The exam- 

 ination brought to light a periodic error that 

 repeated itself in every ten minutes of arc. This 

 was traced to a slight eccentricity of a ratchet- 

 wheel and has been corrected for circles subse- 

 quently graduated with this engine. 



The Clock Vault of the V. S. Naval Observatory: 



Edqae Tillyee. 



In this paper, which was read by Professor 

 Updegraff in the absence of the author, Mr. Tillyer 

 described the devices adopted for maintaining 

 constant temperature in the vault in which are 

 mounted three Riefler clocks. 



On the Construction of Astronomical Photographic 

 Objectives at the U. 8. Naval Observatory: 

 George H. Peters. 



Mr. Peters first described the various attempts 

 that had been made to install a photographic 

 instrument at the observatory with the use of 

 material already at hand, the most noteworthy 

 of these being the reassembling of the parts of the 

 old mounting of the 26-inch equatorial to serve 



as a mounting for various cameras. Mr. Peters 

 has now undertaken the construction of two 10- 

 inch objectives of about 110-inch focus. These 

 are of the type in which three lenses are employed 

 with large separations. The curves were com- 

 puted Ity Mr. Tillyer and the grinding is being 

 done with a machine constructed in the observa- 

 tory shop. 



At the annual meeting of 1908 the society had 

 appointed a committee on luminous meteors. This 

 committee presented a detailed report written by 

 its chairman, Professor Cleveland Abbe, giving a 

 r6sum4 of what had previously been done toward 

 securing photographs of meteor trails. The vari- 

 ous methods and instruments that have been em- 

 ployed or proposed were critically examined from 

 the point of view of the astronomer as well as 

 from that of the meteorologist. The report 

 strongly urged the establishment of a network of 

 photographic stations about one hundred miles 

 apart for the purpose of obtaining a tolerably 

 complete record of all the meteors appearing 

 within the network. Automatic instruments of 

 as simple and inexpensive a type as practicable 

 were recommended. 



The committee on comets, also appointed at the 

 1908 meeting, reported orally through its chair- 

 man. Professor Comstock. Its attention had been 

 given mainly to the approaching return of Hal- 

 ley's comet. In order that this comet may be 

 adequately observed it will be necessary, on ac- 

 count of its close approach to the sun at the 

 time of maximum brilliancy, to have stations 

 widely distributed in longitude. To secure such 

 stations correspondence has been had with ob- 

 servatories in the eastern hemisphere. The Pacific 

 Ocean prasents a wide gap in which no available 

 station exists and the committee has assumed the 

 task of securing funds for the establishment of a 

 temporary station, presumably in the Hawaiian 

 Islands. Such funds are now assured in case the 

 circumstances of the comet's return render it 

 desirable to send out a party. The appearances 

 that the comet will present depend so much upon 

 Lne exact date of its return to perihelion that no 

 definitive program of observation can be framed 

 before the rediscovery of the comet. It appears, 

 however, advisable to separate the observing pro- 

 gram into three classes of observations, viz., pho- 

 tographic, photometric and spectrographic, and 

 the preparation of a detailed program of these 

 divisions has been entrusted, respectively, to Pro- 

 fessors Barnard, Pickering and Frost. It is the 



