320 OBSERVATIONS OF THE MAGNETIC DIP 



VII. Magnetic Dip at Washington city, D. C 

 Place of observation the garden of the Washington Observatory, on Capitol 

 hill, (about 300 yards N. N. W. of the preceding station. ?) 



Date. Hour. Needle No. 1. Needle No. 2. 



1841, Aug. 13, 1— 3i, P. M. Observed dip, Poles direct, 71° 17'. 50 71° 13'.00 



" " " Poles reversed, 11.52 17.80 



Mean dip, 71 14 .51 73 15 .40 



Mean dip of both needles, 71 14 .95 



Remarks. — Weather cloudy, light south wind. The temperature during 

 the observations from 78° to 81°. 



VIII. Magnetic Dip at Baltimore, Md. 

 Place of observation the second square north-east of the Washington monu- 

 ment, station of observation of Professor Bache, and occupied by myself and 

 Dr. Locke, on the 28th April, 1841. (See No. XL, above, in this paper.) 



Date. Hour. Needle No. 1. Needle No. 2. 



1841, Aug. 19, 9— lU, A. M. Observed dip, Poles direct, 71° 32'.40 71° 37'.22 



Poles reversed, 42 .00 32 .00 



Mean dip, 71 37 .20 71 34 .61 



Mean dip of both needles, 71 35 .90 



Remarks. — Sky clear, light south wind. The temperature during the ob- 

 servations from 73° to 79°. 



IX. Magnetic Dip at Baltimore, Md. 

 Place of observation the grove north of the Washington monument, (station 

 of observation of Professor Loomis, as pointed out to me by Mr. T. Green, 

 of Baltimore.) 



Date. Hour. 



1841, Aug. 19, 12—2, P. M. Observed dip, Poles direct, 



" " " , Poles reversed. 



Mean dip. 

 Mean dip of both needles. 



Remarks. — Sky clear, moderate south wind. The temperature during the 

 observations from 83° to 85°. 



X. Magnetic Dip at Baltimore, Md. 

 Place of observation the botanical garden of St. Mary's college. 



Needle No. 1. 



Needle No. 2. 



71° 55'.50 



7I°44'.95 



46.72 



53.10 



71 51 .11 



71 49.02 



needles. 



71 50.06 



