334 TRANS. ST. LOUIS ACAD. SCIENCE. 



-with the upper face (into which a cross is cut) level with the ground. 

 Polaris obs. 



Station 35— Cef/rtr Co., /owa. Lat. 41° 42' . . ; Lon. 91° i4'.2. Farm 

 of Philo Mead, and near the centre of the S.W. qr. of sec. 25, tp. 79, r. 4 

 W. About 250 ft. S. of the house and in the prolongation of the front 

 drive just where it curves eastward. Polaris obs. 



Station 36 — nenr Atabssa, Muscatine Co., loiva. Lat 41° 38'. 4; 

 Lon. 91° 13' • 8- About 60 rods N. of the centre of sec. 2, tp. 78. r. 3. W. 

 About 60 yds. from the road. Observations in a cornfield, 50 rods N. of 

 the house of John Cope. Polaris obs.* 



Station 37 — Luiesville, Bollinger Co., Mo. Lat. 37° 2o'.(,; Lon. 89° 

 58'. g. On the crest of the hill S. of town on open common. The school- 

 house (S.W. corner) lies 200 ft. nearly due E. and the Greenville road lie. 

 W. 100 ft. The first star observation was spoiled by rain ; the second was 

 successful, but a morning fog prevented a morning reading of the marks 

 A sun observation (equal altitudes) was also taken, but the first mark 

 reading was forgotten in the hurry of work. The two observations dif- 

 fered o'.g, and were given equal weight. 



Station 38— Charleston, Mississippi Co., Mo. Lat. 36° 55' .g ; Lon. 

 89° 19' 2- I" the yard of the Fletcher House, 140 ft. N. of the N.W. cor- 

 ner of the building. Polaris obs. 



STkTios ^g — Poplar Bluffs. Butler Co., Mo. Lat. 36° 44'. 4; Lon. 

 90° 21'. g. In a vacant lot on the crest of the hill in front of the house of 

 S. M. Chapman. The centre of the court house dome bears S. 42° 13 '.9 

 W., and the S.W. corner of Mr. Chapman's house bears N. 5° 32'. 7 E. 

 Polaris obs. 



Station 40 a—Dotiifkan, Ripley Co., Mo. Lat. 36° 37'.a ; Lon. 90° 

 46'. g. In the court-house yard. 15 ft. from the E. fence and 18 ft. from the 

 S. fence. Polaris obs. for meridian. The magnetic meridian was deter- 

 mined by a single reading of the magnetic axis at 7 : 19 a.m., and intensity 

 was determined by oscillating magnet Cg. in Declin. No. 3. This deter- 

 mination was reduced to absolute measure by calculating the magnetic 

 moment for that day from the formula expressing its value for successive 

 days, as deduced from the work of the summer. The magnet was oscil- 

 lated in Declinometer No. 3. with the new leveling screw as used in 1879. 

 This station was reached Jjy wagon from Poplar Bluffs, and the roads were 

 so heavy that we were obliged to leave behind all our instruments except- 

 ing Declin. No. 3. 



Station 40 b — Dotiip/iati. This station was 50 ft. W. of S. from the 

 previous station and in line of the mark. A single declination reading 

 was taken at S : 15 a.m. as a check on the previous determination. 



* In all observations thus far made the instrument was covered by a cloth, as we had no 

 tent. The instrument used was Dfclinator No. < and Maj^net Cr,, arranged as in S79. See 

 Trans, iv. i, p. 134. Unless ftherwise stated, intensity observations were hereafter made 

 "with the University Magnetometer. 



