BULLETIN 



ESSEX IIsrSTITTJTE. 



Vol. 11. Salem, Apr., May, June, 1879. Nos. 4, 5, 6. 



The Solar Udijpse of 1878; a lecture hefore the Institute, 



By Winslow Upton, 

 Assistant at Harvard College Observatory. 



Ladies and Gentlemen: — A well known astronomer, 

 who devotes much of his time to studying the appear- 

 ance of the sun, recently remarked that in his opinion the 

 sun was the most important sul)ject for scientific study. 

 Its position as the centre and controlling power of so 

 many celestial bodies places it at the centre also of astro- 

 nomical science, while its intimate connection with life 

 upon the earth renders especially iuiportant any knowl- 

 edge that we ma}^ acquire of its physical constitution. 

 The great interest taken in this study during the last 

 twenty years has added much to our knowledge, and it is 

 a singular fact that this advance has been largely due to 

 observations made during eclipses of the sun, when that 

 bod}^ has been wholl}^ concealed from view. Thus, the 

 spectroscopic discoveries made in the eclipse of 1868 and 

 immediately after, greatly modified the prevailing theo- 

 ries of its constitution. The mere passage of the moon 



ESSEX INST. BULL. XI 5 (53) 



J^- U./^j<j 



