In order to obtain a valid comparison of the results obtained by the group at the University of Wisconsin using the Gulf pendulums with the the results of other observers using other types of modern pendulums, it was necessary to see if tares and systematic effects were present in the other results. The author feels that the tares and systematic effects should be removed from the results of other observers in order to obtain a valid estimate of error. It is felt that the simplest interpretation is probably best in each case.
The pendulum results of other investigators studied include the magnetically compensated Brown invar pendulums of the U. S. Coast and Geodetic Survey, the Cambridge invar pendulums, the GSI quartz pendulums, the Dominion Observatory bronze pendulum apparatus developed by Thompson (1959), and the CGI molybdenum pendulums.
It was important to use the same method of analysis for the results of all observers to test the validity of the method adopted in this paper of station sequence gravity result computation and estimation of variance from re-occupation closures after removal of systematic effects.
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International Gravity Measurements
“Originally established to test reliability of the world network of firstorder international gravity bases, the program was expanded to include establishment of a series of reliable pendulum gravity control measurements in North America to assure a potential accuracy of 1 mGal or better on any global series of measurements. Studies also expanded and standardized existing gravity surveys of the United States for reliable gravity anomaly maps, and evaluated reliability and gravity standards used for global work.”