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Sometimes the earth strata lie horizontally with little irregularity. There we may hope to ignore the effects of migration. Seismic rays should fit a simple model with large reflection angles occurring at wide offsets. Such data should be ideal for the measurement of reflection coefficient as a function of angle, or for the measurement of the earth acoustic absorptivity $1/Q$. In his doctoral dissertation, Einar Kjartansson reported such a study. The results were so instructive that the study will be thoroughly reviewed here. I don't know to what extent the Grand Isle gas field typifies the rest of the earth, but it is an excellent place to begin learning about the meaning of shot-geophone offset.