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Popular Science Monthly 



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-►DIRECTION OF SUN 



EARTH 



MOO;N 5 SHADOW 



MOON 



This diagram, drawn to scale, shows the earth, the moon and the moon's shadow during 

 the echpse. The distance of the sun is 390 times the distance between earth and moon 



have had the privilege of welcoming 

 scores of astronomers from Europe. One 

 large American observatory — the Cham- 

 berlin Observatory, at Denver — will not 

 need to send out an expedition, as it is 

 situated right in the path of totality. 

 The unusual length of this path within 

 accessible territory is a particularly 

 favorable circumstance, for the reason 

 that observers at western stations, after 

 viewing the eclipse, will have ample time 

 to telegraph to those at eastern stations, 

 calling attention to any features that 

 especially demand further observation. 



By hiding the sun and cutting off the 

 glare of sunlight in our atmosphere, an 

 eclipse makes it possible for us to see the 

 envelope of incandescent gases by which 

 the sun is surrounded, known as the 

 chromosphere. Beyond the chromosphere, 

 and extending millions of miles into 

 space, is a pearly white glow, of irregular 



outline, known as the corona. By means 

 of a marvelous instrument called the 

 spectroscope astronomers are able to 

 see and to photograph the chromosphere 

 and its prominences at any time; but the 

 corona can never be observed except 

 during a total eclipse. The spectroscope 

 is also applied, while an eclipse is in 

 progress, to a study . of the chemical 

 composition and the movements of these 

 solar envelopes or atmospheres. 



In past eclipses eager search was made, 

 by photography and otherwise, for a 

 possible planet, or planets, lying within 

 the orbit of Mercury — the nearest to the 

 sun of the planets now known — and ob- 

 servations of an "intramercurial planet" 

 were occasionally reported. These ob- 

 servations were, however, undoubtedly 

 erroneous and astronomers the world 

 over have generally given up hope of find- 

 ing such a planet. 



About eighty-five towns are directly in the path of the total eclipse. Since we are 

 saving daylight add an hour to the times on the map. The track of totality extends 

 from Washington to Florida. Outside of this track, in a belt varying in width from seventy 

 miles at its western end to forty-five miles at its eastern, a partial eclipse will be visible 



