332 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 52 



that a more effective use of available funds might have been found. 

 But the aim of the Solar Observatory differs essentially from that 

 of any other American institution. Hitherto the study of the Sun 

 has been conducted at a disadvantage, partly for lack of suitable 

 instrumental means and partly because of the obstacles arising from 

 unfavorable atmospheric conditions; yet it would be easy to demon- 

 strate that no other star in the heavens is so w^ell worthy of our in- 

 vestigation. As the central body of the solar system, controlling the 

 motions of the planets, and making life possible upon the Earth, the 

 Sun has always been an object of admiration, and sometimes even 

 of worship, to mankind. A permanent decrease of one hundred de- 

 grees (about 0.6 per cent) in the effective temperature of the Sun 

 is considered by good authorities to be sufficient to produce another 

 Ice Age on the Earth. So great a change could hardly occur; but 

 smaller variations, due to internal causes, or to modifications in the 

 absorbing power of the Sun's atmosphere, are very probable. Since 

 solar phenomena follow more or less definite cycles of change, a bet- 

 ter understanding of them might conceivably permit variations in 

 its radiating power, sufficient to determine seasons of good or bad 

 harvest, to be in some degree anticipated. The importance of solar 

 research from this standpoint is thus sufficiently obvious. 



But if the Sun commands our attention as the source and support 

 of terrestrial life, it must appeal no less strongly to every intelligent 

 person as the unique means of opening to us a knowledge of stellar 

 development; for the student who would untangle the secrets of the 

 universe recognizes in the Sun a typical star, placed conveniently 

 within reach and exemplifying the physical and chemical conditions 

 which are repeated in millions of other stars so far removed that 

 they appear to us only as minute points of light. If we are to form 

 a true estimate of the nature of these distant stars, and find the means 

 of tracing out the progressive stages in their development from the 

 nebulze, we must base our investigations upon solar research. 



The great disk which the Sun exhibits in our telescopes would 

 shrink to the size of a needle point if removed to the distance of the 

 other stars. This may be made clearer through a simple comparison. 

 Consider the dimensions of the solar system so reduced that the 

 diameter of the Earth would be one foot and that of the Sun 109 

 feet. The distance between them would then diminish from 

 95,000,000 to 2.2 miles, but the proportionate distance of the nearest 

 fixed star would be 600,000 miles. This illustrates the comparative 

 nearness of the Sun and the great advantages thus aft'orded of ob- 

 serving its various phenomena. 



