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Figure 17.4 Ocean bottom trawl 181 



Figure 17.5 Precision depth recorder 182 



Figure 17.6 Magnetometer 183 



Figure 17.7 Gravity meter 185 



Figure 17.8 Data generator 185 



Figure 17.9 Seismic refraction 186 



Figure 17. 10 Reflection technique 188 



Figure 17. 11 Sparker record 188 



Figure 17. 12 Puerto Rico Trench 189 



Figure 17. 13 Ocean bottom seismograph 191 



Figure 17. 14 Ray paths in deep-sea sound channel 192 



Figure 17.15 Acoustic position keeper 194 



Figure 17. 16 Thermal probe 195 



Figure 17. 17 Large-volume water sampler 195 



Figure 17. 18 Sound velocities in sediments 196 



Figure 18. 1 Phytoplankton 198 



Figure 18.2 Zooplankton 199 



Figure 18.3 Modified Van Dorn water sampler 201 



Figure 18.4 Submarine photometer 202 



Figure 18.5 Three -qixarter meter quantitative plankton net. 203 



Figure 18.6 High speed plankton sampler 204 



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