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LIGHT SCIENCE FOR LEISURE HOURS. 



delineation caused many men of science to be long led 

 astray, till photography finally came to their rescue, is 

 that of the solar corona. The pictures of the corona 

 which used to be drawn by different observers of the 

 same eclipse, often by observers stationed within a few 

 yards of each other, showed such discrepancies as to 

 suggest to some the theory that the corona is not 

 really a solar appendage, but an optical phenomenon, 

 caused by the passage of the sun's rays through our 

 own atmosphere ; and although a very slight knowledge 

 of mathematics sufficed when applied (for many mathe- 

 maticians, failing to apply their knowledge, were long 

 misled) to show the erroneous nature of this theory, it 

 was not until photography had been employed to 

 delineate the corona, that the groundlings were con- 

 vinced on this comparatively simple point. A singular 

 illustration of the inferiority of the unaided vision in 

 this matter was given once at a meeting of the 

 Astronomical Society. ' Two people,' said Mr. Stone, 

 referring to the eclipse of 1875, which he had witnessed 

 in South Africa, ' were asked to make drawings of the 

 corona, and at the end of the time one man had drawn 

 it in one shape, and the other as different as it could 

 possibly be.' Considerable amusement was caused by 

 Mr. Stone's sketching two absurdly dissimilar pictures 

 on the blackboard. The person who drew one picture 

 was an engineer, and was sitting side by side with the 

 other. Before the eclipse was over he turned round to 

 look at the other's drawing, and said, ' What on earth 

 are you doing here ? ' He replied, * I am drawing the 



