ASTEOXOMY A:N^D METEOEOLOGY. 



THE OBSERVATIONS OF THE MATTOON EXPEDITION ON THE 

 GREAT ECLIPSE OF 18C9. COMMUNICATED FROM THE DUDLEY 

 OBSERVATORY, AT ALBANY. 



The niglit preceding the day of the eelipse was one of unusual 

 anxiety to the observers, from tlie faet that about G oVloek it be- 

 gan to rain, and eontinued ahiiost witiiout intermission until 11 

 P.M. In onler to learn the worst, we went to the telegraph offices 

 and asked for weather reports from west and east. At nearly all 

 the stati<ms from which reports had been received, extentiing 

 from Omaiia to Cincinnati, it was rainy or cloudy. These reports 

 led us to expect a storm extending over a large area of territory. 

 And it^was presumed that il would l)e a day or two in passing 

 over. But fortunately our prognostics were in error, for at 11 

 o'clock P.M. the rain ceased, and stars began to make their ap- 

 pearance. The morning of the 7th was perfectly clear, with not 

 a cloud to be seen, and it so continued during the whole day and 

 subsequent night. It was one of those rare days but seldom seen 

 in this climate ; the atmospheric disturbance being at a minimum. 



One hour before the beginning of the eclipse, observations 

 were made on the solar spots, and their position and magnitude 

 mapped on a diagram prejiared for the purjiose. As the time 

 drew near for the lir^t contact of the moon's limb, each observer 

 examined carefully the region wlnne the moon was expected, to 

 see whether it would be visible before contact with the solar disc. 

 Tiie closest scrutiny of five observers failed to discover it. 



At 10 seconds before the true contact of the limbs, a lunar 

 mountain, distant 8 or 10 degrees north of the contact-point, 

 plunged into the solar disc, and was recorded on the chronograph. 

 The true contact of the limbs was well observed by all, and at 

 nearly the same instant. The moon's limb, instead of appearing 

 round, as it should, was nearl}' Hat and a liitle notched, siiowing 

 a mountainous region. As the eclipse advanced, observations 

 were made by means of the micrometer and chronograph for 

 measuring the relative position of the two bodies. When the sun 

 w;/S about one half eclipsed, a red band of light was seen sur- 

 rounding the limb of the moon over the solar disc. Later, during 

 the progress of the phenomenon, tails of light were seen project- 

 ing out tangent to the moon's limb, and extending 15 or 20 de- 

 gi'ees along the edge. 



As the crescent of solar light grew less and less, every eye was 

 intently watching for an unusual appearance. Nearly a minute 



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