160 ABSTEACTS: PHYSICS 



2. In the United States there was found a decided relation between 

 the sign of the gravity anomalies and the coast, but there was not found 

 any apparent relation between the anomalies and any other class of 

 topography. 



3. In the United States there was found a decided relation between 

 the gravity anomalies and the Pre-Cambrian geologic formation. In 

 both the United States and in India there was found a decided rela- 

 tion between the gravity anomalies and the Cenozoic formation. No 

 relation between the gravity anomalies and the geologic formations 

 was found in Canada. 



4. It was found from certain computations and investigations that 

 the local distribution of compensation of the topographic feature is in 

 general nearer the truth than regional distribution of the compensa- 

 tion out to a distance from the station of 167 kilometers. It was not 

 proven whether local distribution is more probable than a regional dis- 

 tribution out to a distance of 59 kilometers from the station. 



5. The best formula, resulting from this investigation, by which 

 theoretical gravity may be computed for any latitude at sea level was 

 based upon 348 stations; it is 



To = 978.039 (1+ 0.005294 sin 2 - 0.000007 sin 2 2 0) in which y 

 is the value of gravity sought and 4> is the latitude of the station. 



6. From the constants of the above gravity formula, was derived 

 the value of 297.4 for the reciprocal of the flattening of the earth. 

 This value of the flattening is very close to other values recently derived 

 from gravity data in the United States and elsewhere. 



7. The cause of the greater part of the anomalies is believed by the 

 author to be in general the deviation from normal in the densities in 

 the outer portion of the earth's material and probably not far below 

 sea level. 



The titles of a number of articles dealing with isostasy or related 

 subjects are given. W. B. 



PHYSICS. — A specific gravity balance for gases. J. D. Edwards. 

 Bureau of Standards Technologic Paper No. 89. Pp. 20. 1917. 

 The need of an accurate method for determining gas densities has 

 been especially urgent in the natural gas industry. To supply this 

 need the apparatus described in this paper was designed. The balance 

 is enclosed in a gas tight chamber and consists of a beam which is sup- 

 ported on 2 needle points, and which carries on one end a relatively 

 large globe and on the other a small counterweight. The gas to be 



