COMPARISON OF COMPENSATION RESULTS 



301 



III. Comparison of Differences in Anomalies for Pairs of Stations with local 

 and regional Compensation (all computed by Hayford Method) 



Station. 



Difference in anomaly (in dynes), sub- 

 tracting lower from higher station. 



Differ- , 



Elevation. ence Local 

 in ele- compen- 

 vation. sation. To 12 To 37 To 104 



Regional compensation. 



A 



Meters. 



Mauna Kea, Hawaii 3,981) 



Honolulu, Hawaii 6 ( 



Gornergrat, Switzerland 3,016) 



Saint Maurice, Switzerland.. 419 ( 



Pikes Peak, Colorado 4,293} 



Colorado Springs, Colorado . . 1,841 ( 



Yavapai, Arizona 2,179) 



Grand Canyon, Arizona 849 ( 



Mount Hamilton, California. 1,282} 



San Francisco, California . . . 114 ( 



miles. 

 Dyne*. 



miles. 

 Dynes. 



miles. 

 Dynes. 



Cloudland, Tennessee 

 Hughes, Tennessee 



1,890} 

 994 J 



Meters. Dynes. 



3,975 +.131 +.118 +.105 +.068 



2,597 +.046 +.041 +.023 +.016 



2,452 +.02S +.020 +.016 +.012 



1,330 +.011 +.010 +.010 +.012 



1,168 +.020 +.020 +.011 +.029 



896 +.033 +.031 +.031 +.031 



Means for 6 pairs + .045 + .040 + .033 + .028 



Means for 4 pairs in United States +.023 +.020 +.017 +.021 



The mean differences of anomaly show greater accordance for regional 

 compensation to 104 miles than for local compensation. The number of 

 pairs is too small, however, to more than indicate that this method should 

 also be considered in studying the question of regional compensation. 



It is of interest that these differences are all positive, as I previously 

 pointed out. 19 Bowie has studied this effect in the anomaly results on 

 comparing adjacent stations of materially different elevation. 20 His sug- 

 gested explanations do not appear to make these results the less useful in 

 considering the question of regional compensation. The effects men- 

 tioned would affect the groups of stations in much the same manner that 

 they do the results from the pairs. For 14 pairs of stations an average 

 difference of +.013 dyne is found, all the results but one being positive. 

 There is here fairly strong evidence of a systematic variation in the 

 gravity anomalies of about this amount as between stations so located. 

 This indicates the possibility of the existence of systematic effects in the 

 reductions not yet definitely located. 



19 Science. December 20. 1912, p. 869. 



20 Coast and Geodetic Survey Special Publication No. 40, p. 93. 



