14 CARNEGIE INSTITUTION 



with this project and equally commended to favorable attention was 

 another project for the construction and maintenance of a large re- 

 flecting telescope to be used in stellar researches. 



In the domain of astrophysics there appears to be no direction 

 in which there is a more hopeful prospect of a marked advance in 

 knowledge to follow a large investigation wisely planned. 



It is not surprising that the nature of the sun should have been 

 an object of speculation from the earliest times. In the estimation 

 of mankind generally the sun seems to be obviously the most impor- 

 tant of the celestial bodies. From the astronomer's point of view, 

 however, the sun has another interest which is not less intense and 

 not less impressive. 



The sun is a star. It is the only star near enough to us to permit 

 of detailed study into its physical constitution. The next nearest 

 star of whose existence we are now aware is nearly three hundred 

 thousand times more distant than the sun. It should not be difficult 

 to understand that if we wish to study the physical condition and 

 history of stars under such difficulties of distances, it would be an 

 immense gain if we could attain detailed knowledge as to any one 

 of them which might happen to be near. The sun offers this oppor- 

 tunity. 



It is already known that a great variety of successive stages of 

 development seem to be illustrated in the analysis of the spectra 

 which the stars present. There appears to be no link missing from 

 the hottest and brightest to the coldest and least luminous. In the 

 study of this development, then, it is manifest that we should gain 

 a great advantage — the key to the position — if we could thoroughly 

 know the physical constitution and tendencies of one in this series 

 of stars. The sun is the one which offers this opportunity. 



But astronomers have sought to take advantage of this opportu- 

 nity during three centuries. For the last fifty years an immense 

 total of effort has been expended on this research. For more than 

 forty years the spectroscope has been in the hands of astronomers as 

 an effective weapon of solar research. There are numerous institu- 

 tions where solar research is now actively carried on. Where, then, 

 is the field which would justify a special eft'ort on the part of the 

 Carnegie Institution to enter upon solar research at the present time ? 



The expanding record of our knowledge relating to the physical 

 constitution of the sun is parallel with that of increase in the power 

 of the appliances used in this research. 



