Guiding lights, 81 Gyroscope, the, 93, 100 H Half-tone illustrations, 181 "Hard-pan," 14 Harris, Sir W. S., 36 _Hawke_ and _Olympic_, collision between, 198 "Head" of the torpedo, 99 Heat and electricity, 37 Heat of the electric arc, 123 Heat, testing by, 205 Helium, 33, 75 Hertz, 154 Howitzers, 241 Hughes, Prof., 159 Humphrey Gas Pump, 231 Hydraulicing, 112 "Hydro-carbons," 45 Hydrogen, liquid, 73 Hydrometer, the, 65 Hydrostatic valve of torpedo, 101 "Hyper-radial" apparatus, 88 I Ice, machine-made, 71 Indigo, synthetic, 44 Inductance, 154 Induction coil for wireless, 162 Induction furnaces, 129 Insulating ink, 177 "Interference" of light waves, 159 Ionisation of the atmosphere, 172 Iron, 109 J Jupiter's moons, 150 K Kelvin, Lord, 28 Kerosene, 46 Kieselguhr, 12 Kilowatt, the, 25 Kinematograph in coal mine experiments, 146 Korn, Prof., 183 Krypton, the gas, 75 L Leclanche cell, the, 23 Leyden jar, the, 153 Light, speed of, 151 Light waves, 151 Lighthouse, the, 78 Lighthouse lamp, the, 83 Limit gauges, 209 Liquid air, 73 Lodge, Sir O., 159, 161 Lumière autochrome process, 216 M Magnetic detector, the first, 168 Magnetic pole, the, 90 Magnetism, 25 Magnets, 25 "Making" light, the, 79 Maltster, the, 50 Mansfield Rescue Station, the, 224 Marconi, 161 Marshy ponds, to remove by dynamite, 17 Mash tun, the, 50 "Master compass," the, 97 "Master" records, 60 Maxwell, J. C., 152 Measuring by electrolysis, 62 Mendeluff's table, 74 Mercury, 114 Metallographic testing, 205 Metals, testing, 204 Methane gas, 10, 124 Methyl alcohol, 49, 53 Microbes, their use, 43 Mine-laying, 105 Mine-sweeping, 107 Molecules, 56 Morris, William, 233 Mud, gold from, 122 Muirhead, Dr, 167 Murette or pedestal of lighthouse lamp, 85 N Naphtha, 45 National Physical Laboratory, 199 Natural frequency, 161 Neon, the gas, 75 Nickel chrome gun steel, 239 Nitric acid, 11 Nitro-cotton, 12 Nitro-glycerine, 11 Nitrogen gas, 9 Nobel, inventor of dynamite, 12, 135 Nodes, 157 O Ohm, the, 22, 24 Ohmmeter, the, 27 Ohm's law, 27 Oil, mineral, 44 Oil-producing countries, 47 Optical apparatus of lighthouse, 86 "Orders" of lighthouse apparatus, 88 Ores, 110 Orthochromatic plates, 212 Oscillations, electrical, 36 Oscillatory circuit, 154 Oscillograph, Duddell's, 39 Oxide of iron, 133 Oxyacetylene flame, the, 131 Oxygen gas, 10 Oxyhydrogen jet, 130 P Paraffin wax, 45 Patents, 174 "Periodicity," 36 "Personal equation," the, 207 Petrol, 45, 52 Petroleum, 44 Phonograph, the, 60 Plans of a ship, 199 Plates of the secondary battery, 64 Platinum, 184 Plumbago in plating, 59 Poulsen arc, the, 173 Poulsen, Valdemar, 165