224 ASTRONOMY. 



given by the presence at Hong Kong of the United States surveying 

 ship Polos, with Commanders Green and Davis, U. S. X., who are 

 determining longitudes by telegraph throughout the China seas. 



The Etna Observatory. — The building is partially completed, and siir- 

 niounted by its revolving dome for the protection of the great Merz 

 equatorial of 35 centimeters aperture. The observatory will not be 

 ready to be opened until 1882. Great difficulties have to be surmounted 

 in the building ; all the materials have to be conveyed 3,000 meters above 

 the level of the sea, and the season when work is possible is only three 

 months out of the year. The mounting of the equatorial is finishetl, 

 and the construction of the meteorological apparatus is going on. 



Tabor College, in Southwestern Iowa, has just received a fine telescope, 

 the joint gift of theEev. Mark Hopkins, D. B., ex-i)resident of Williams 

 College, and the Eev. C. V. Spear, i)rincipal of Maplewood Seminary, 

 Pittsfield, Mass. 



Prof. C. A. Young has lately determined the position of the observa- 

 tory of the scientific school of Princeton College. The longitude was 

 determined by telegraphic exchange with Washington. It is 9™ 34^.538 i 

 0^021 (7 nights). The latitude observations were in 5 series. The re- 

 sults were: 



I. + 40O 20' 57".791 i 0",U8 

 II. 57 .763 ±0 .116 



III. 57 .815 iO .067 



IV. 57 .771 iO .173 

 V. 57 .775 ±0 .088 



Series 1 is 82 observatious on niue nights of 28 stars, with a transit 

 by Kahler used as a zenith telescope. This telescope has a brolen tube. 



II is 59 observations of 49 pairs on two nights, with same instrument. 



III is 114 observations of 49 i)airs on three nights. 



IV is 33 observations of 29 pairs on two nights, with a Fauth transit 

 used as a zenith telescope. 



V is a series of 37 prime vertical observations from 11 stars. 



The final value of the latitude has a probable error of i 0".044, 

 something less than 4 feet on the surface of the earth. These numbers 

 are worth quoting, as showing the accordant results which careful ob- 

 servers can obtain with small instruments. 



INSTKTJMENTS. 



A refractor of 21 inches. — A short time ago the largest refractor in 

 the world was successfully completed by Mr. Grubb, of Dublin, who has 

 just had conferred upon him by the university of that city the honorary 

 degree of master of engineering. This instrument has a steel tube 3^ 

 feet in diameter at the center, tapering toward each end, of course. In 

 length this tube is 33.5 feet, and the aperture is 27 inches. At first it 

 was thought that the disks could be finished in a year by M. Feil, of 



