Geophysical Instruments and Accessories-Namely, Borehole Logging Equipment, Consisting of Natural Gamma Radiation Logging Instruments; Nuclear Gamma Radiation Logging Instruments of the Gamma Gamma and Neutron Neutron Variety; Electric Logging Instruments which Measure Self Potential, Resistivity, Induced Polarization, and Borehole Fluid Conductivity; Sonic Logging Instruments; Borehole Flow Metering Instruments; Temperature Measuring Instruments; Hole Direction Determination Instruments, Surface Surveying Equipment, Consisting of Natural Gamma Radiation Surveying Instruments (Scintillation Counters); Electrical Surveying Instruments which Measure Self Potential, Resistivity, and Induced Polarization; Magnetic Surveying Instruments; Gravity Surveying Instruments