None
426 Eeactions, Armature, 399 Eeduction Factor, 228 Eelation of Charge and Potential, 54 Eeluctance, magnetic, 347 Eeplenisher, the, 77 Eesistance, unit of, 213 ; specific, 216, 277 ; of galvanometer, 274 ; of a battery, 275 Eesistance Boxes, 240 Eesistances, comparison of, 264 Eesultant Electric Force, 47, 48; at a point, 47 Eesultant Magnetic Force, 125 Eontgen Eays, 426 Eotation of a magnet, 339 Secondary Batteries, 205 Secular variations of the Earth's magnetism, 178 Self-induction, 378 Sensitive Galvanometers, 232 Shells, Magnetic, 325 Shunts, 242, 364 Shuttle wound Armature, 394 Sine Galvanometer, 229 Sine and Tangent Laws, 148 Single fluid cells, 200 Solenoid, 330 Spark, the Electric, 72 Specific Eesistance, 216, 277 Square, Law of the Inverse, 155 440 INDEX Standards of electromotive force, 204 Storms, magnetic, 179 Strength of the Pole of a Magnet, 130 Surface Density, 24 Surfaces, Equipotential, 31, 53 ; and lines of force, 34 Survey, Magnetic, 174 Susceptibility, 129 Tangent Galvanometer, 227 ; con- struction of, 230 Tangent Laws, 148 Telegraph, the electric, 406 Telegraphy, wireless, 416 Telephone, the, 408 Temperature, 29 ; influence of, 130 Tensions and Pressures in Magnetic Field, 118 Theories of Electrical Action, 23 Theory, of Magnetisation, 130, 355; Volta's, 309 Theory of Potential applied to Electrical Attraction, 41 Thermal effects of a Current, 191 Thermo-electricity, 293 ; observa- tions on, 294 Thermometer, the Platinum, 300 Thermopile, the, 299 Thomson effect, the, 298 Torsion Balance, Coulomb's, 87 Total Magnetic Charge, 124 Tracing lines of Force, 114 Transformations in electrolysis, 304 ; in a Voltaic cell, 306 ; of energy in a motor, 402 Transformers, 391 ; principles of, 388 Transmission of magnetic force, 414 Tubes of Force and Electric Cur- rents, 186 Two fluid batteries, 202 Uniform Field, Magnet in a, 135 ; measurement of the strength of a, 163 Unit of Capacity, 285 Unit of Current, practical, 225 Unit of Inductance, 379 Unit Magnetic Pole, 123 Unit of Potential, 51 Unit of Resistance, 213 Units of Measurement, 46 Vacuum, contact experiments in, 313 Variations, secular, 178; daily, 178 ; annual, 178 Voltaic Cell, the, 182, 197 ; chemical theory of, 219; contact theory of, 221 ; transformations in, 306 Volta's Theory, 309 Voltmeters, 254,366; electrostatic and multicellular, 97 Voss Machine, the, 85 Water-dropping Accumulator, the, 85 Waves, Electric, 414 Weston Cell, the, 205 Wheatstone's Bridge, 268 Wimshurst's Machine, 79 Wireless Telegraphy, 416 Zero of Potential, 29 oambuidoe: ruiNTici) by j, b. T. 