270 



ON THE MAGNETIC DIP AT SEVERAL. 



These observations were made between the hours of twelve and two, 

 P. M.j the mean temperature being 86° F. In the experiments made 

 at the same place by Captain Ross, as quoted by Professor Lloyd in 

 the Fifth Report of the British Association, 



« Needle B" gave the dip 69° 01 -'5, 

 "Needle P", " " « 69 42-0, 



and these were the extremes; from the mean of which my mean 

 result differs only two minutes. It differs, however, from the mean of 

 all Captain Ross's experiments, with eight different needles, near six 

 minutes of a degree. 



The follovi^ing results were obtained at the garden of N. Long- 

 worth, Esq., in Cincinnati, latitude 39° 6' N., longitude 84° 27' W., 

 November 26, 1837. 



No. of Needle. 



Polarity. 



Limb of In- 

 strument. 



Face of 



Needle. 



Indication. 



Mean. 





f 



E 



E 



70° 32' 







A 



E 



W 



70 56 







W 



E 



70 39 









^ w 



W 



70 53 





1. 

















E 



E 



71 20 







B 



E 



W 



70 25 







W 



E 



71 21 







^ 



. w 



r E 



W 

 E 



70 10 



71 20 



70° 47' 







A 



E 



W 



70 20 







W 



E 



71 15 









. w 



W 



70 14 





2. 



1 















r E 



E 



70 33 







B < 



E 



W 



70 51 







W 



E 



70 33 







'- 



L, W 



W 



70 50 



70° 44'-5 



70° 45'-75 



At Dayton, in the state of Ohio, latitude 39° 44' N., longitude 

 84° 11' W., March 26, 1838, the dip • 



