Dip and Variation of the Magnetic Needle. 113 



Central position lat. 32° 48' N., Ion. 84° 19' W., ^=-l°.0443, 

 i. e. -5° 2'.7, a;= + . 000795, ?/= + .006077. Mean of the dif- 

 ferences at the seven most northern stations, +3'.0; nine most 

 southern, — 2'.3 ; four stations having the greatest computed va- 

 riation, — 1'.7; five least, — 2'.2; seven intermediate, -f2'.6. 



Central position, latitude 32° 6' N., longitude 91° 8' W., d= 

 -l°.958l, i.e. - 7° 57'.5,a; = + .000911,?/=+. 005797. Mean 

 of the differences at five northern stations — 2'. 8 ; four southern 

 + 3'.7; two eastern +1'.0; three western +1'.7; four interme- 

 diate -r.7. 



Central position, latitude 39° 12' N., longitude 89° 22' W., 

 5=-l°.58465, i.e. -7°35'.l, a;=-.000S99, y= + .008730. 

 Mean of the differences at five northern stations — O'.S; five 

 southern +0'.8 ; three having greatest computed variation — 9'.6,- 

 three least +3'. 6; four intermediate +4'.5. 



Vol. XLiii, No. 1.— April-June. 1342. 15 



