NIPHER 5^*^ ANN. REP. MAGNETIC SURVEY OF MISSOURI. 523 



Pacific R.R. track measures 200 ft. Passing freight trains caused the nee- 

 dle to swing through 2'. Polaris obs. on elongation. 



Station ^46 — Warren ion, Warren Co. Lat. 38° 46' ; Ion. 91° 08' . 

 The station is at theW. end of town, about a mile from the station of 1881. 

 Starting at the creek bridge W. of the court-house, the station will be found 

 by going along the road westwardly 705 ft., thence southwardly at right 

 angles to the road a distance of 45 ft. The court-house spire bears S. 79* 

 14.5' E. Polaris obs. on elongation. 



Station 147— /a St. Charles Co. Lat. 38° 43'; Ion. 90° 40'. The sta- 

 tion is in the Booneslick road about midway between the track and the S. 

 fence, and almost due south of O'Fallon.* The O'Fallon road is 250 ft. E. 

 The house of D. Heald lies a few rods to the W. Polaris observation on 

 elongation. 



Station 148—/// St. Louis Co. Lat. 38° 41'; Ion. 90° 21'. On the St. 

 Charles rock road. The station was in a gap in the fence opposite the 

 grounds of J. B. Lucas. From the station to the centre of the road the 

 distance is 30 ft. From thence along the road to a point opposite the gate 

 is 165 ft., while the distance in the opposite direction to a point opposite 

 the S.E. corner of the Lucas grounds is 158 ft. Polaris observation on 

 elongation. 



Station 149— A^e«/- Atah'ssa, Muscatine Co., Iowa, on the farm of Mrs. 

 Grace Aikins, on the N.E. qr. of the N.W. qr. of sec. 3, tp. 78, r. 3 W. 

 The station is on the front path, exactly between the front gate and the 

 house. This station is a mile west of station 33 in the report of i88o.t 

 Polaris obs. 



Station 34 — This station was occupied in 1880, and is described in the 

 report for that year. Polaris obs. on elongation. 



At six of the stations of the summer deflection determinations 

 were made with the University magnetometer, with magnet Cg 

 deflecting and Cj^ deflected, and these observations have been 

 used in determining the value of P, and in calculating the mag- 

 netic moment of Cg for the summer. The latter was sensibly 

 constant, the observed difterence between the extreme value 

 observed and the mean of all being about o-oo^j, of the average 

 moment. In the reduction of the work the magnetic moment 

 was therefore assumed to be constant. The calculations for P 

 and for the magnetic moment are given in the adjoining tables. 



* In the report for 18S0 the Ion. of O'Fallon should be 99' 40'. 



t Station 33 is on the N.E, qr. of the N.W. qr. of sec. 2, and not N.E. qr. of N.E, qr. 

 as was given in the report of iSSo. 



iv 3 Q [April 2, 1844. 



