33^ TRANS. ST. LOUIS ACAD. SCIENCE. 



A solar compass determination of declination was made here by Pum- 

 pelly and Moore in 1872, the resulting value being 11° 30'. A polaris 

 observation was made here. Mr. J. deGoncer, engineer for the Pilot Knob 

 Iron Co., made the transit observations for oscillation, in a most efficient 

 manner. 



Station 43 c — Top oi Pilot Knob. This station was also occupied by 

 Pumpelly and Moore, their value for declination being 4° 30' E. The 

 station is marked by a drill-hole cut into the porphyry, at the centre of a 

 white cross which is painted on the rock. Observations on this cap rock, 

 which overlays the hematite, show that it is filled with magnetic poles 

 within a few inches of each other, and sufficiently strong to reverse the 

 position of the needle of a pocket compass. When raised upon the tripod, 

 Pumpelly and Moore found the deviation from the normal direction to be 

 on the average 2° to 3°, and the greatest deviation from the normal value 

 in the Pilot Knob region was 7° 30' to 8°. In our determination the 

 needle was 50 inches above the face of the rock. The meridian here was 

 deduced from the observations at station " b." 



Station 44 a — De Soio, Jefferson Co., Mo. Lat. 38° 06'. g ; Lon. 90° 

 34'. 3. On the crest of the hill almost due W. of the railway depot. The 

 meridian was determined by a sun observation. The result of the declina- 

 tion determination gave a value greater than was expected by more than 

 a degree. The result obtained the next day was 12' more. The reason 

 for this difference is not known, although it is known that it was not an 

 error in reading, and there was no part of the work which did not seem 

 satisfactory excepting perhaps the sun observations, and this does not 

 account for the difference, which was due to a change in the determination 

 of magnetic meridian. The record of the sun observations was made by 

 Mr. Jno. L. Downer of De Soto, in the absence of Mr. Woodward. Mr. 

 Downer also made the telescopic determinations in the oscillation series. 

 The declination determination having been unsatisfactory here, it was 

 repeated at 



Station \\ b, which is about a mile E. of the former, on the farm of 

 Chas. Fitch, not far from the middle of the N. line of the S.W. qr. of sec. 

 I, tp. 39, r. 4 E. Observations made in the edge of the meadow N.E. of 

 the house. Polaris observation. 



Station 45— ^/>«;«5w/c-t, Jefferson County, Mo. Lat. 38° 19'. g*, Lon. 

 90° 25'. g. On the grounds of the Montesano Springs Co., 250 ft. from the 

 south road fence, and 525 ft. S.W. of the S.W. corner of the hotel. Sun 

 observations. 



Station 46 — Pac^/fc, Franklin Co., Mo. Lat. 38° 28' .2 ; Lon. 90° 

 43'. g. Observations 1250 ft. N. of the depot, and 95 ft. and 180 ft. from 

 the E. and W. elms, and 135 ft. from the oak, all large trees standing 

 alone. Sun observations. 



In this region the declination changes very rapidly to the S. 



