THE GRAVITY OBSERVATIONS OF 1 895 COMPARED 



297 



average elevation anomalies of 1895 show substantially as great an im- 

 provement over the two older methods, judged b} r the accordance and 

 range of the anomalies, as do the Hayford anomalies of 1912. 



Different constants were used in these two latter reductions, and, to 

 obtain a more direct comparison between them, constant corrections are 

 applied, -|-.008 to the 1895 anomalies and +-002 to the 1912 anomalies, 

 to make the algebraic sum of the anomalies for the 25 United States sta- 

 tions zero for each group respectively. This is equivalent to the custom- 

 ary procedure of adding a constant term on the assumption that gravity 

 in the United States, as determined by the stations considered, is normal. 

 The results are given in Table II. 



II. Comparison of Anomalies in the Force of Gravity by the 1895 and the 1912 

 Reductions, Gravity normal in the United States 



Anomalies (in dynes), g observed, — g 

 computed. 



Station. 



For 25 stations in United States, observa 

 tions in 1894 and 1895 : 



Washington, D. C. ( Smithsonian) 



Ithaca, New York 



Charlottesville, Virginia 



Deer Park, Maryland 



Colorado Springs, Colorado 



Denver, Colorado . 



Pikes Peak, Colorado 



Gunnison, Colorado 



Grand Junction, Colorado 



Green River, Utah 



Grand Junction, Colorado 



Norris Basin, Wyoming , 



Lower Geyser Basin, Wyoming 



Pleasant Valley, Utah 



Salt Lake City, Utah 



Austin, Texas (capitol) 



Austin, Texas (university) 



Laredo, Texas , 



Galveston, Texas 



New Orleans, Louisiana , 



Calais, Maine 



Cambridge, Massachusetts , 



Boston, Massachusetts , 



Princeton, New Jersey , 



Philadelphia, Pennsylvania 



r 



Average elevation 

 reduction (Put- 

 nam, 1895). 



New method 



(Hayford, 



1912). 



Dynes. 



Dynes. 



+ .023 



+ .039 



— .021 



— .023 



—.011 



— .013 



+ .003 



+ .010 



+ .011 



— .007 



+ .008 



— .016 



+ .014 



+ .021 



+ .043 



+ .020 



+ .041 



+ .024 



+ .005 



— .021 



—.002 



— .002 



+ .024 



+ .021 



+ .007 



—.001 



— .005 



+ .004 



+ .010 



+ .010 



—.028 



— .008 



— .030 



— .010 



.043 



— .020 



— .027 



— .009 



— .025 



— .013 



— .007 



— .008 



+ .005 



+ .005 



+ .007 



+ .005 



— .024 



— .019 



+ .019 



+ .022 



