No. XXI. 

 OBSERVATIONS 



' On ihe Comet of 1811. 



By JEREMIAH DAY, Prof, of Math, and Nat. Philo. in 

 Yale College. 



ON the 9tli of September laft, I began a courfe of 

 obfervations, on the Comet which has lately withdrawn 

 from our view. They were continued, with confider- 

 able intervals of interruption, till the 1 3th of January. 

 Though I v/as poUefled of no inftrument, which would 

 give the place of the Comet, with the utmofl precilion ; 

 yet the obfervations were fufliciently correct, for a de- 

 termination of the elements of its orbit, with a near 

 approach to exactnefs. 



Few Comets have prefented themfelves to our view, 

 under circumftances more favourable, for obferving their 

 motions. Many have appeared for a few days, and 

 then, fuddenly retired. But this was vifible, for fev- 

 erable months, even to the naked eye. During this 

 period, it traverfed a fpace, of more than 1 30 degrees, 

 in the heavens. A s:eneral idea of the direction of its 

 motion may be obtained, by conceiving a great circle 

 to be drawn through the ftar », in the extremity of 

 the tail of the Great Bear ; and the bright ftar in the 

 Eagle. It was near the lirft of thefe, on the 2d of Oc- 

 tober ; and very near the latter, on the I ft of Decem- 

 ber, as Mr. Bowditch had predicted, two months be- 

 fore. It paiTed acrofs the conftellation of the Great 

 Bear, the head of Afterion, the right arm of Bootes, 

 the northern part of Hercules, the Eagle, and the bow 

 of Antinous ; and when I faw it laft, on the i Sth of 

 January, it was a little fouth of the head of Equuleus. 

 Clouds intercepted the view of it, one or two of the 

 following evenings ; then fucceeded a period of moon- 

 light ; and, when the moon had pafted the full, the 



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