338 TRANS. ST. LOUIS ACAD. SCIENCE. 



STArios SO— I^owell Co., Mo. Lat. 36° 56' .q ; Lon. 91° 55' -a- This 

 station is on the farm of Thomas Pottles, which is on the N.E. qr. of the 

 N.E. qr. of sec. 16, tp. 26, r. 9 W. of 5th pr. meridian. The house is situ- 

 ated just at the base of the hill and at the junction of the Houston and 

 Salem roads. The observations were made 23 ft. N. and 25 ft. W. of the 

 N.W. corner of the (log) house. The determinations were made in the 

 same manner as at Houston. 



Station si—Beardsiown, Cass Co., Ills. Lat. 40° cC; Lon. 90° 29'.o. 

 Complete observations were made on the N. side of Main st. at its inter- 

 section with Adams st. and a few rods from the shore of the Illinois river. 

 Pole-star observation. 



At this station on the 9th of August, beginning at 7 : 20 o'clock a.m., a 

 remarkable disturbance was noted. Between 7 :20 and 7 :35 the easterly 

 variation increased 7' .3, and by 7 :49 it had diminished an equal amount. 

 At this time the needle did not oscillate over a greater arc than o'.g, and 

 the single fibre of silk on which the needle was suspended had been used 

 since July 28, so that no part of this disturbance could have been due to 

 torsion. The needle could at times be seen to move, and eight readings 

 were taken during the disturbance. 



This disturbance does not seem to have been noticed elsewhere, al- 

 though they were generally observed on the nth. 



Station 52 — JVeiv AiAens, Si. Clair Co., Ills. Lat. 36° 10'. 3; Lon. 

 89° 55' .^. Observations were made in order to locate the 6° line, which 

 enters S.E. Missouri at some point not yet accurately determined. Obser- 

 vations were made on a vacant lot owned by Aug. Kirchner, and distant 

 50 ft. from the W. fence on Kaskaskia st. and 80 ft. from the N. fence. 

 Polaris observation at -western elongation. No evening mark reading. 



Station 53— O'Fallon, St. Charles Co., Mo. Lat. 38° 46' .g ; Lon. 

 90° 43' •2- I" the yard of Dr. W. C. Williams, 53 ft. from the front fence 

 and 52 ft. from the line of the S. side of the house. A polaris observation 

 was made at eastern and also at western elongation. Intensity was deter- 

 mined by an oscillation series with Cg in Declin. No. 3, in which Prof. H. 

 S. Pritchett, of Morrison Observatory, observed the magnet scale, the 

 watch being read by myself The moment of Cg was calculated for Aug. 

 9th, although the observations were made Oct. 31, as the magnet remains 

 quite constant when not in use, as is shown by the determinations of 1879 

 and 1880. 



Station 54 — i?<?//«, Phelps Co., Mo. Lat. 37° 57'. g-, Lon. 91° 45'. q. 

 The observations at this station were made by Prof. Emerson, of the Rolla 

 School of Mines. The instrument used was a solar compass. The obser- 

 vatipns were made in the spring of 1880 and were continued over 8 or 9 

 days, observations having been made at 6 and 9 a.m., 12 m., and 3 and 5 

 P.M. The mean value is given as 6° 53' , which agrees very well with the 

 Salem observations. The true meridian was determined four or five years 



