32 CARNEGIE INSTITUTION 



pletion of this one quarter would greatly enhance the value of what 

 has been already accomplished. 



The demand for this work may be stated under three principal 

 heads : 



1 . The primary utility of this work would rest upon its immense 

 importance in studies relating to the stellar system. The work 

 mentioned already under ( i ) would enable us to study the structure 

 and motions of the sidereal system so far as this is represented by 

 stars to the seventh magnitude. The extension of this work b)^ 

 means of (2) would take us to stars of the ninth magnitude, for 

 which the older records of observations contained observed positions 

 of the greater part. We should then be able to extend our studies 

 upon the sidereal problem to stars ten times as numerous and more 

 than six times fainter than those of the seventh magnitude. The 

 feasibility of reaping the full fruits of this undertaking through the 

 present generation of astronomers is not so great as for the brighter 

 stars, but that which would be demonstrably attainable now in this 

 direction fully warrants the enterprise. Furthermore, the comple- 

 tion of this monumental work, so that the accurate position of every 

 star from the north to the south pole, down to the ninth magnitude, 

 would be known for epochs near the beginning of the century, would 

 be an achievement upon which the entire civilized world could look 

 with pride. 



2. The positions of these stars determined in this work would 

 possess very great value as reference points in all micrometric work 

 upon faint stars, nebulae, comets, and planets observed by means of 

 •extra-meridian telescopes. This alone was originally looked upon 

 as fully warranting the labor of the entire enterprise. 



3. This M^ork would furnish the reference stars needed in the 

 work of the Astrographic Chart, which has for its aim the determi- 

 nation of accurate positions for all stars down to the eleventh mag- 

 nitude. This forms the third step in a series of investigations which 

 seek to determine the accurate positions of stars at successive epochs 

 in order that we may ultimately learn their motions. The accuracy 

 of which this third step is capable depends upon the accuracy of its 

 basis, which must be the meridian observation of telescopic stars. 

 The only difficulty is that the accuracy of the observ^ations hitherto 

 made under the program of the AsUvnomische Gesellschaft is not re- 

 garded as sufficient for the purposes of the Astographic Chart, as 

 Director L,oewy has pointed out. He recommends as a substitute 

 for (2) the special determination of the star positions required for 



