Circular slide rule with case, Shot Point Indicator, plastic. designed by Input/Output Inc, Houston, Texas, United States of America, made by Fearns Calculators, England, 1960-1980
Slide rule, Shot Point Indicator, four concentric disks in white plastic with numbers engraved onto edges/surfaces, with case, plastic.
Probably used in Seismology
The outer disk - 7.25" Disk shows data for the Ground Station
Middle Disk - 6.70" Disk shows data for RLS Input
The Inner Disk - 5.87" Disk shows Recording Channel data
Input/Output Inc, Houston, Texas - Shot Point Indicator
Made in England by Fearns Calculators, Dunston, Gateshead,