OCTOBBR 31, 1902.] 



SCIENCE. 



693 



grees 55 minutes, Washington is admirably 

 situated for. mailing observations intended 

 to supplement the work of the European 

 observatories and at the same time that of 

 the observatories of the southern hemi- 

 sphere. It is twelve and one half degrees 

 south of Greenwich, twenty degrees south 

 of Pulkowa and seven and one half degrees 

 south of the new branch of the Pulkowa Ob- 

 servatory at Odessa. Stars of thirty de- 

 grees south declination are observed on the 

 meridian at Washington at an altitude of 

 twenty-one degrees and very near, the 

 zenith at Cordoba and the Cape of 

 Good Hope. Being ten to fifteen de- 

 grees south of the observatories of central 

 Europe, and yet far enough north for ac- 

 curate observation of the circumpolar stars, 

 perhaps no location better in this respect 

 could be found for extending the accurate 

 star places of the northern hemisphere 

 thirty degrees or more south of the equator 

 for comparison with the results of observa- 

 tions made in the southern hemisphere. 



The value of the great work on the posi- 

 tions of the stars which has been carried 

 on at Greenwich during the two hundred 

 years which have elapsed since Flamsteed's 

 time is recognized by every astronomer. As 

 an example of continuous activity directed 

 toward a definite end it is perhaps without 

 a parallel in the history of science. Until 

 1850 a transit instrument of five inches 

 aperture and a mural circle six feet in 

 diameter, both by Troughton, were used. In 

 that year the present Greenwich transit 

 circle of eight inches aperture and twelve 

 feet focal length was mounted by Airy. The 

 axis is six feet long and the divided circle 

 is six feet in diameter. While one of the 

 most powerful instruments of its kind in 

 the world, its construction is such as to 

 make it liable to systematic error. No 

 meridian mark is provided, although the 

 north collimator was at one time used as 

 such, and the spirit level is not used. Fur- 



thermore, the instrument cannot be re- 

 versed. 



The great value of the fundamental work 

 which the Pulkowa Observatory has done 

 during the past sixty years is generally 

 recognized. The instruments used have 

 been of the best quality and their construc- 

 tion has been improved from time to time. 

 The methods of observation are of the high- 

 est class and the systematic errors of the 

 results have been found to be very small. 

 But at the extreme north latitude of Pul- 

 kowa, the altitude of the sun on the meri- 

 dian at the winter solstice is only seven 

 degrees, and stars at the celestial equator 

 are observed at an altitude of only thirty 

 degrees. As a consequence the best work of 

 that observatory is limited to stars of north 

 declination. With the good judgment and 

 enterprise which have from the first charac- 

 terized the management of the Pulkowa 

 Observatory, the branch observatory, men- 

 tioned above, was established in 1898 at 

 Odessa, thirteen degrees further south, 

 where valuable work is no doubt being 

 done. 



But all instruments . and all methods of 

 observing have their peculiar forms of 

 error, and it seems clear that the establish- 

 ment of a third center in the northern 

 hemisphere for continuous fundamental 

 observations of the stars is very desirable. 

 Milton Updegraj'f. 



U. S. Naval Obsekvatoky, 

 Washington, D. C, 

 •June 15, 1902. 



THE CARNEGIE INSTITUTION. 

 The provision for research constitutes a 

 supremely important part of the intellec- 

 tual organization of a great nation. A 

 profound recognition of this fact has 

 brought into existence the Carnegie Insti- 

 tution. I have elsewhere recorded (The 

 Dial, February 16, 1902) my appreciation 

 of the general aims and purposes of this 



