James Freeman Gilbert ( August 9 , 1931 -- August 15 , 2014 ) was an American geophysicist , best known for his work with George E. Backus on inverting geophysical data , and also for his role in establishing an international network of long-period seismometers .
J. Freeman Gilbert ( August 9 , 1931 -- August 15 , 2014 ) was an American geophysicist . He was best known for his work with George E. Backus on inverting geophysical data and also for his role in establishing an international network of long-period seismometers .