2 E. DEGOLYER 
instrument was completed by 1890. Various determinations were 
made in the laboratory and in the field, and the instrument was 
modified and refined both as to mechanical system, insulating housing, 
and recording until, in 1902, E6tvés introduced the double-beam 
instrument which is essentially the instrument of today. 
The first exhaustive field investigation by Edtvés was carried out 
in rgor on the ice of Lake Balaton, in order to avoid the computation 
of terrain effects, but surveys were soon extended into the Great 
Hungarian Plain where such corrections were necessary. 
E6tvoés designed and built his instrument for geodetic research; 
geodesy and physics being his main interest in the instrument, the 
methods, and the field surveys throughout his entire life, except that 
during the first decade of the present century, he demonstrated the 
possibility of interpreting buried regional geological structure from 
a consideration of gravity anomalies. He apparently believed that 
the precision of his instrument was great enough and the gravity 
expression of smaller structures such as anticlines and domes was 
sufficiently definite for them to be mapped by torsion balance surveys. 
The more definite understanding of the possibilities of the instru- 
ment as a geological tool was mainly the realization of the geologist 
Hugo V. Boeckh who, in 1917, first called attention to the fact that 
anticlines and domes with light or heavy cores could be located by 
means of the torsion balance, citing surveys and the existence of such 
anticlines at Gbely (Egbell): The American geologist, Eugene Wesley 
Shaw, suggested the possibility of using gravity anomalies in a search 
for salt domes in the same year. In 1918, Schweydar, with the advice 
of Boeckh, employed the method to delineate the boundary of an 
explored German salt deposit. 
The possible use of the balance was again discussed in early 1919 
with the late Dr. Th. Erb, when in charge of exploration throughout 
the world for the Dutch-Shell group. Dr. Erb said that his group 
had investigated the method and that it appeared to be theoretically 
sound but that they had not yet made a practical test. 
In 1920, I learned that one could then purchase or contract tor 
the construction of torsion balances. After lengthy consideration, a 
joint field research was arranged between the Amerada Petroleum 
Corporation and the Mexican Eagle Oil Company. Two instruments 
were contracted with Ferdinand Siiss, Budapest, and construction 
was commenced in August, 1921. Donald C. Barton was sent to 
Budapest in May, 1922, to receive the finished instruments, which 
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