5<D LIGHT SCIENCE FOR LEISURE HOURS. 



THE ECLIPSE OF 1870. 



ASTRONOMERS have passed yet another of those stages 

 which mark their progress towards a fuller knowledge 

 of solar physics. That strange peculiarity of the 

 celestial phenomena presented to us inhabitants of 

 earth, by which our satellite is able just to blot out 

 from view the great central luminary of the planetary 

 system, has yet once more served us in good stead. 

 The few brief seconds during which the sun remained 

 concealed on December 22 last have supplied the means 

 of testing those rival theories which had been pro- 

 pounded respecting the solar corona, and, as it seems 

 to me, of arriving at definite conclusions as to the 

 general nature of this interesting object. 



In passing, it may be well to notice how important 

 an influence that peculiarity respecting the apparent 

 dimensions of the sun and moon, to which I have 

 just referred, has exercised on the progress of astro- 

 nomy. We are so accustomed to the near equality 

 of the sun and moon as respects their apparent size, 

 that we are apt to overlook^the factUhat this apparent 

 equality must be regarded rather in the light of a 

 fortunate accident than as in any way an essential 

 attribute of the orbs which rule the day and the night. 

 In the whole range of the solar system there is no 

 other instance of so remarkable an association. In 

 Mercury and Venus of course no eclipses of any sort 

 can occur, because these planets have no moons. 



