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CARNEGIE INSTITUTION 



plored region of the ultra-violet. For these reasons astronomers 

 are agreed that the construction of a large reflecting telescope at the 

 present time would open up many fields of investigation, in which 

 results of great value would undoubtedly be obtained. 



Such a telescope, which would greatly surpass all existing instru- 

 ments in power, should be used first in the northern hemisphere, 

 and subsequently south of the equator, where the southern heavens, 

 as yet unexplored with comparable optical power, offer limitless 

 possibihties of discovery and research. With it there could be ob- 

 tained a series of large scale photogi^aphs of the nebulge, which 

 would serve as standards of reference in years to come for the de- 

 tection of evidences of motion or development. In conjunction 

 with spectrographs of moderate and high dispersion, the latter 

 mounted on fixed piers in constant-temperature laboratories, it 

 would be possible to stud}^ stellar spectra and to trace the evidences 

 of stellar evolution in a manner qrate beyond existing means. 

 Variable stars, which at their period of minimum are too faint to 

 be seen in the most powerful instruments, could be followed through 

 all their phases. The .spectra of variable stars, which have been 

 but little studied, could be investigated to the greatest advantage. 

 Another important use of a large reflector would be in the measure- 

 ment of the heat radiated from the stars. For this work a refracting 

 tele.scope is useless, but the researches on stellar heat by Nichols at 

 the Yerkes Observatory with a small reflector shows that much 

 could be done with a large instrument of this type. 



Respectfully submitted. 



George E. Hale. 



Appendix D to Report of Committee on Astronomy. 



THE QUANTITY AND NATURE OF SOEAR RADIATION.* 



By S. p. Eangley. 



The study of the Sun may be pursued from two standpoints, in a 

 measure distinct from one another. On the one hand we may re- 

 gard it as the nearest and therefore most readily studied of the stars, 

 and seek to know its materials and their arrangement and reactions, 

 in order to apply the results so gained to enlarge our views of the 



* Prepared in answer to request from Advisory Committee on Astronom:,- of 

 tbe Carnegie Institution, May, 1902. 



