On the Meteors of 13th November, 1833 



145 



Although these elements indicate a parallax in the right direction, 

 yet there is some want of correspondence between the amount of par- 

 allax and the differences of latitude in the several cases. Between 

 New Haven and Worthinglon, the parallax in Dec. is only 1° 3(y, the 

 difference of Lat. being 1° 14/, while between New Haven and Em- 

 mittsburg, the parallax is 3° 45', the difference of Lat. being 1° 38/ 



Owing to the want of correspondence between these elements, we 

 shall form a different estimate of the distance, according as we derive 

 our data from one pair or another of these observations. The appa- 

 rent radiant being stationary, we may suppose the Dec. taken by each 

 observer, at the moment when that point was on his meridian. The 

 difference of Lat. will represent the distance corresponding to the par- 

 allax. Neglecting for the present all considerations of the earth's 

 spherical figure, and of refraction, we may in a very simple man- 

 ner, obtain an approximate expression for the distance as follows. 



Let AB represent a horizontal line, and the angle BCD, the alti- 

 tude of the radiant point, 74° 5', as seen at Emmittsburg, in Lat. 

 39° 40', C being the place of observation. Let A be the place of 

 observation at New Haven, in Lat. 41° 18' ; then the angle at D will 

 represent the parallax in Dec, namely, 3° 45', and the angle 74° 5'- 

 3° 45'=70° 20'=CAD; and the side AC = 1° 38'= 112.7 miles. 



Hence, Sin 3° 45 



Sin 74° 5' 



112.7 



J 657 



8.815599 

 9.983022 

 2.051924 



12.034946 

 3.219347 



That is, the observations at Emmittsburg, compared with those at 

 New Haven, give the distance from New Haven to the source of the 

 Meteors, sixteen hundred and fifty seven miles. 



Fig. l . 



Fig. 2 

 B 



3° 45 



D 



B 



Vol. XXVI.— No. 1. 



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