The Evolution of the Sciences 



The totality of the eclipse is reached at differ- 

 ent times at successive points of the zone, and 

 observers were obliged to establish their observa- 

 tories along the centre line and not near the 

 edges of the strip, because there the eclipse is 

 of maximum duration, varying from 2 minutes, 

 28 seconds in Labrador to 3 minutes, 45 seconds 

 in Spain. 



The previous total eclipse of 28th May 1900 

 had a duration of only i minute, 19 seconds; 

 thus the eclipse of 1905 presented much more 

 favourable conditions, enabling photographs to 

 be taken with the prolonged exposure necessary 

 for bringing out all the details of the external 

 corona. In addition, the longest eclipses are 

 also those in which the sun is most completely 

 hidden by the moon's disc, so that less light 

 from the photosphere is, in such cases, mingled 

 with the actual light of the corona. Spectro- 

 scopic investigation is greatly facilitated by 

 this condition. 



The eclipse of 1905 was also specially inter- 

 esting for another reason. The observation 

 of solar spots, which has been attentively 



pursued for a hundred and fifty years, has 



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