Il8 CARNEGIE INSTITUTION 



In other words, we strive to determine with reference to some fixed 

 system of imaginary circles upon the sky the location of the brighter 

 stars. This results in the determination of the positions and mo- 

 tions of the stars — the practical outcome. These positions, so deter- 

 mined, become the basis of reference for planetary astronomy, for 

 the tables of the nautical and astronomical almanacs, and for the 

 extension of the work of precision by mere differential processes to 

 the great multitude of fainter stars. Thus, the fundamental obser- 

 vation of the principal stars is the real foundation upon which rests 

 the entire structure of the astronomy of position. 



The leadership in extent and importance of work in this line 

 must be accorded to the observatory at Pulkowa and to the two 

 English Royal observatories, respectively at Greenwich and the 

 Cape of Good Hope. Good work of this kind has been accom- 

 plished at various other observatories in Europe, but none in the 

 United States up to the present time. 



There is, however, a class of observations of precision falling 

 little short of those which are really fundamental, in respect to 

 which the instances of successful accomplishment are more numer- 

 ous. Some of the notable contributors in this line have been the 

 observatories at Dorpat, in Russia ; Konigsberg, Berlin, Bonn, and 

 Strassburg, in Germany ; Paris, in France ; Leiden, in Holland ; 

 Oxford, Cambridge, and Edinburgh, in Great Britain ; Melbourne, 

 in Australia ; Madras, in India ; Cordova, in the Argentine Re- 

 public, and the observatories of Washington, Mount Hamilton, 

 Cambridge, Cincinnati, Madison (Wis.), and Albany. 



After these, upon a scale of precision scarcely inferior in many 

 instances and on a par in importance, rank the observations of the 

 positions of faint stars by secondary methods, either with the me- 

 ridian circle or through astronomical photography. This is dis-' 

 tinct from the general or exploratory charting, which has been 

 described and which is the step naturally preliminary to measure- 

 ment of precision. The historic zone observations by Lalande, 

 Bessel, L,amont, Argelander, and Gould are examples of this class. 

 To observations of this class we owe a large share of the exact 

 knowledge which has hitherto been acquired as to what is happen- 

 ing in the stellar universe. Some thirty years ago the German 

 Astronomical Society assumed leadership in an undertaking to ob- 

 serve all stars down to the ninth magnitude in the northern sky 

 (over 100,000 stars). The Harvard College Observatory and the 

 Dudley Observator)' were participants in this work. The former 



