63 



sunlight in the corona ; if it passes beyond the sun but 

 not through it, it shows that the polarization is caused by 

 light passing through the corona, which must, then, con- 

 tain substances capable of producing the phenomenon, 

 unless polarization can be produced in other ways than 

 those now known. Most of the polariscopic observations 

 of the corona show reflected light. 



Besides these that have been mentioned there are other 

 minor sul)jects of study in an eclipse, such as the changes 

 in temperature, the changes in the color of the sky and 

 earth, the shadow as it sweeps over the earth with a veloc- 

 ity of half a mile each second, the effect of darkness upon 

 living creatures — and we must not forget the search for 

 new planets near the sun, which, as we shall see later, 

 will render the eclipse of 1878 especially memorable. 



The day of the eclipse was favorable at all the observ- 

 ing stations. To those in Colorado the clear weather 

 was a glad surprise, for there had been no day for two 

 weeks in which the eclipse could have been successfully 

 observed. The preliminary observations and adjustments 

 had in consequence been but partially made. The ob- 

 servers on the summit of Pike's Peak were obliged to 

 abandon some of their plans, as there was not time to 

 adjust the instruments. At our station, we worked in 

 the early morning hours till daylight and to a late hour 

 in the evening following the eclipse to complete the aux- 

 iliary observations. As the day advanced the linal prep- 

 arations were completed, and in the early afternoon, a 

 few moments before the predicted time, the expectant 

 observers took their appointed stations. No one would 

 have imagined that a wonderful event was at hand. No 

 trace of the moon could be seen. The face of Nature 

 bore its accustomed aspect. But almost upon the ex- 

 pected moment, a little notch upon the sun's western limb 



