138 Sioux City Academy of Science and Letters. 



ists respecting the origin, constitution and destiny of 

 the sun and solar system. The progress of knowledge in 

 solar physics during the past half century has been, as 

 we have seen, one of marvelous development, but the 

 knowledge so attained only suggests the greater possi- 

 bilities and triumphs with which the future abounds. 



"Not in vain the distance beacons, 

 Forward, forward, let us range! 

 Let the great world spin forever 



Down the ringing grooves of change." 



REFERENCES CONSULTED. 



(a) The Sun, by C. A. Young, page 335; see also Popular Astronomy, 



Northfield, Minn. April, 1904. 



(b) The Sun, by Young, page 88. 



(c) Proc. Royal Society, 1901, December. 



(d) The Sun, Young, page 113. 



(e) The Solar Surface During the Past Twelve Years, Hadden, Proc. 



Iowa Academy Sciences, Vol. X, page 86. 



(f) Ibid, pages 74-93. 



(g) Monthly Notices Royal Astron. Society, June, 1903. 

 (h) Astrophysical Journal, January, 1904. 



(j) Manual of Astronomy, Young, page 246. 



(k) Problems in Astrophysics, Gierke, chapter XIV. 



(m) The Sun, Young, page 144. 



(n) Popular Astronomy, April, 1904. 



(p) Die Strahlenbrechung auf der Sonne, 1891. 



