986 



SUBJECT INDEX 



Moment : 



electric -, 672, 697 



magnetic - (see Magnetic moment) 

 Monacite sand, 55 

 Moon, effect of, on gravitational field, 



162-164 

 Motor generator {see Generator) 

 Muaslira series, 678 

 Mud: 



density of -, 74 , 



drilling - (see Drilling mud) 



- volcanoes, 886, 887 

 Muscovite, dielectric constant of, 666 



N 



Nacatoch formation, 432 



Nagelflue, heat conductivity of, 849 



Nagyagite, density of, 77 



Naphthalenes, 889 



Naphthenes, 889, 890 



Natural density, 76, 77 



Natural earth currents and potentials 

 (see Spontaneous potential) 



Natural frequency (see Frequency) 



Navarro shale, 285 



Navigation, 9, 64, 940, 942, 949, 951 



Near-surface interference, 31, 745, 763, 

 764, 808, 809, 815, 817 



Negative potential center, 26, 27, 668, 

 669, 671, 675, 677 



Nephelite, density of, 80 



Nephelite basalt: 

 density of -, 80 

 susceptibility of -, 314 



Nephelite-syenite, density of, 81 



Nephrite, susceptibility of, 313 



Neutron, 872 



Newtonian potential, 145 



Newton's law, 16, 85, 87, 89, 144, 145 



Nickel : 

 damping resistance of -, 482 

 magnetostrictive properties of -, 317, 

 318, 947 



Nickel ores, 50, 73, 289, 310, 385, 415, 416 



Nicollite, resistivity of, 657 



Nitramon, 485, 486, 490, 571 



Nitrates, 54 



Niveau surfaces of gravity (see Equipo- 

 tential surfaces of gravity) 



Noise : 

 detection of -, 9, 35, 58, 59, 63, 64, 

 935, 938, 941, 942, 948, 951, 958, 

 960-962 

 prevention of -, 36, 37, 935, 943 



Nomographs, 202, 203 



Nonastatic gravimeters (see Gravi- 

 meters, unastatized) 



Nonmetallic mining, geophysical ex- 

 ploration in, 52-56 



Nonpolarizable electrode (see Elec- 

 trode) 



Norite : 



coercive force and remanent magneti- 

 zation of -, 316 



density of -, 80 



elastic moduli of -, 467 



radioactivity of -, 874 



Rayleigh wave velocity of -, 473 



susceptibility of -, 313 



transverse wave velocity of -, 473 

 Normal : 



- electrical field, 683, 693, 694, 697 



- electromagnetic field, 766, 770-773, 



776-779, 801 



- equipotential lines, 682, 683, 693, 

 697, 699 



- geothermal gradient, 847 



- gravity, 141 



- gravity gradient, 210 



- magnetic field, 377 



- potential differences, 670, 678 



- ratio (P.D.R.), 746, 747, 754, 756 



- travel-time curve, 499, 500 

 Northern hemisphere, 211, 212, 293, 295, 



375, 416 

 Nucleus, 870-873 



O 



Observatory, magnetic, 2, 3, 362, 366-369 

 Obsidian: 



density of -, 81 



elastic moduli of -, 467 



heat conductivity of -, 849 

 Oceanography, 3, 42 

 Oerstedt unit, 298 

 Oertling balance, 193 

 Ohm-centimeter, 633 

 Ohm-foot, 633 

 Ohm-inch, 633 

 Ohm-meter, 633 

 Ohm's law, 632, 633, 683 

 Oil: 



composition of -, 890 



direct location of -, 5, 9, 33, 45, 47, 

 825, 831, 837, 856, 884, 886-888, 

 894, 902-910. 



- exploration, 4, 5, 19, 25, 33, 43-48, 



70, 157-161, 272-286, 422-433, 439, 

 441, 498, 499, 503, 623, 736-739, 

 755, 761, 805, 817, 825, 835-837, 

 856-858, 862, 864, 867, 884, 886- 

 888, 892-906 



cost of -, 47, 48 



reconnaissance and detail methods 

 in -, 45 



- formations, resistivity of, 665, 830 

 geothermal effects of -, 842, 848, 



856, 858 

 radioactivity of -, 35, 864, 876, 884 



- in rock pores, 76, 830 



- sand: 



radioactivity of -, 864, 876, 884 

 resistivity of -, 665, 830, 831, 837 



- seepages, 886, 887 



