Masterpieces of Science 



the planets, " adds this observer, "is in an almost 

 hopeless condition at present; yet much may be 

 expected when an increased sensitiveness of the 

 plates has been secured." No plate as yet pro- 

 duced is fully responsive throughout the whole 

 range of the telescopic eye. Clearly enough, 

 the draughtsman has not been ousted from 

 every corner of the observatory as yet, although, 

 in most of its tasks, his services have long ceased 

 to be required ; in one of them the embarrassment 

 of the camera is not a lack but an excess of light. 

 Professor Janssen of the observatory at Meudon, 

 near Paris, long ago succeeded in making the 

 best photographs of portions of the sun's 'surface; 

 he has always used the wet-plate process, which, 

 from its slowness, gives the best results with the 

 intense solar beam. 



Just at the turning point between old and new 

 methods of recording the phenomena of the sky, 

 there was a contrast between them which was 

 decisive. On July 29 1878, a total solar eclipse 

 was so widely observable throughout the United 

 States that forty to fifty drawings were made 

 of the corona, duly published by the United 

 States Observatory, Washington, two years 

 afterward. Says Professor Barnard: "On ex- 

 amination scarcely any two of them would be 

 supposed to represent the same object, and none 

 of them closely resembled the photographs taken 

 at the same time. The method of registering 

 the corona by free-hand drawing under the con- 

 ditions attending a total eclipse received its 

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