Lightning, 451, 454; effects of, 456;
ascending, 436; conductor, 458, 506;
globe, 454
Light, 309; absorption of, 311; de-
composition of, 356; diffused, 320;
dispersion of, 356; electric, 477;
intensity of, 316; propagation of,
312; recomposition of, 363; reflec-
tion of, 318; scattered, 320; sources
of, 310; velocity of, 315
Lighthouses, 355
Limit of magnetisation, 408, 495
Line wire, 500; neutral, 399
Litre, 106
Lodestone, 398
Long sight, 395
Loops, 194
Liquefaction of gases, 262; of va-
pours, 258
Liquids, 5; buoyancy of, 82; con-
ducting power of, 223; equilibrium
of 86, 89; expansion of, 231; fixed,
243; level of, 87; pressures from,
80; specific gravity of, 105; super-
posed, 91; volatile, 243
Luminiferous ether, 309
Luminous point, 310; globe and tube,
434; jar, 445; effects, 477
MACHINE, 32; weighing, 52
Mackerel sky, 289
Magdeburg hemispheres, 118
Magic lantern, 382; pane, 433
Magnetic attraction and repulsion,
400; batteries, 409; dip, 407;
equator, 407; effects of electrical
discharge, 450; fluids, 401; in-
duction, 402; meridian, 405; needle,
398, 400, 485; poles, 401, 407;
stone, 398; substances, 402
Magnetisation of the earth, 408; by
currents, 488; limit of, 408, 495;
by magnets, 408; by touch, 408
Magnetism, Ampère's theory of, 495;
and electricity, 482
Magnetoelectrical machines, 511
Magnets, action of current upon, 483;
of the earth on, 404; consequent
points of, 399; distribution of mag-
netic force in, 399; in the earth,
485; induction by, 509; influence
of, in magnetic substances, 402;
natural and artificial, 398
Major chord, 178; semitone, 178
tone, 178
Malleability, 75
Manhole, 274
Manometer, 137; compressed air,
137; open air, 137
Mares' tails, 289
Mariner's card, 295; compass, 406
Mariotte's law, 136
Marloye's harp, 188
Mason's apparatus, 83; hygrometer,
Pedal, 187
Pendulum, 57; application of, to clocks,
62; compensation, 230; compound,
58; electrical, 412; simple, 58; laws
of, 59; verification of laws of, 60
Penumbra, 314
Percussion, heat due to, 301
Periscopic glasses, 395
Permanent gases, 262
Permeable strata, 96
Perturbations, 405
Phantasmagoria, 383
Phantoms, 383
Phenakistoscope, 364
Phial of four elements, 91
Phosphorescence, spontaneous, 310
Photoelectrical microscope, 385, 386
Photography, 390
Photometer, 316; Bunsen's, 317
Physics, definition of, 1.
Physiological effects of the electric
discharge, 444, 475, 514
Piano, 183, 187
Piezometer, 77
Pisa, tower of, 47
Pitch, 174; concert, 181; pipe, 196
Plane, inclined, 54; mirrors, 324
Plante's battery, 511c
Plumb line, 41
Pluviometer, 291
Pneumatic syringe, 301
Points, power of, 421
Polar Aurora, 459
Polarity, austral and boreal, 404
Poles, flattening of the earth at, 31; of
the magnet, 399,400; magnetic, 407
Poles and electrodes, 468
Polyorama, 384
Positive electrical fluid, 412; on glass,
391; plate, 467
Pound avoirdupois, 106
Powers, 20
Presbyoptic, 395
Presbytism, 395
Press, hydraulic, 85
Pressure, atmospheric, 116; conden-
sation by, 258; equality of, 78;
heat due to, 301; horizontal, 80;
of an atmosphere, 134, 250; on a
liquid, 251; on a body in a liquid,
97 supported by a man, 135
Primary coil, 509; tones, 183
Prism, 343; paths of rays in, 344
Proof plane, 421
Propagation of light, 312; of sound,
161, 164
Pseudoscopes, 397
Psychrometer, 281
Pumps, 141, 145, 150, 151.
Pupil, 394
Pyrheliometer, 302
Pyrometers, 210
UADRANT electrometer, 424
Quadrant of the meridian, 106
RADIANT heat, 211-213
Radiating powers, 220
Radiation, laws of, 212; solar, 302
Radius of the earth, 31
Rain, 291; gauge, 291
Rainbow, 369
Ramsden's electrical machine, 423
Rarefaction, measurement of, 142
Ray, incident, 215, 318, 335; re-
flected, 318, 335
Real expansion, 231
Real image, 332; in double convex
lenses, 351; and virtual images,
324, 332
Réaumur degree, 205; scale, 205
Receiver, 141, 142, 262; air-pump, 141
Recomposition of white light, 363
Reed instruments, 190, 192
Reflected ray, 318, 335
Reflecting telescopes, 377
Reflection, angle of, 215; of heat,
215, 216; internal, 340; of light,
318; from transparent bodies, 326;
regular, 319; irregular, 319; of
sound, 167; specular, 320
Refracting substances, 337
Refraction, 335; angle of, 335;
change of, to reflection, 340; ex-
perimental proofs of, 338; of heat,
341, 354; laws of, 336; limit of, 340;
various effects of, 339; through
prisms and lenses, 342-350
Refractive index, 336
Refractory substances, 236
Refrangibility, aberration of, 370
Refrigerating rooms, 307
Regulator, 267, 270
Reis's telephone, 516
Relay, 507
Repulsion, magnetic, 400
Resin electrophorus, 425-
Resinous electricity, 413
Resistance, electrical, 417, 488
Resistances, 20, 33
Resonance, 168; box, 181; globes,
183; of air, 182
Resultant forces, 24-25-27
Simple microscope, 379
Single-action machine, 267
Sirocco, 297
Sleet, 293
Slide valve, 269
Slow discharge, 438
Snow, 293
Solar microscope, 386; radiation,
302; spectrum, 356; time, 354
Solenoids, 491, 493, 494
Solids, 5; conductivity of, 223; ex-
pansion of, 227, 228; specific gravity
of, 103. 105
Solidification, 239
Solution, 241
Sonometer, 186
Sonorous body, 160
Sound, 160; intensity of, 169; limit
of, 176; post, 187; in pipes, 190;
propagation of, 161; reflection
of, 167; transmission of, 170;
not propagated in vacuo, 163;
velocity of, 165; in gases, 165;
waves, 161
Sounder, 504
Spark, electrical, 427
Speaking trumpet, 171; tubes, 170
Specific gravity, 103; tables of, 106
Specific gravity, 235; bottle, 105;
flask, 104, 105; of liquids, 105;
properties of bodies, 6; of solids,
104, 105
Specific heat, 264; of solids and li-
quids, 265; table of, 265
Spectacles, 381
Spectroscope, 361, 362
Spectrum, 356; analysis, 360; colours
of, 357; effects of, 358; dark lines
of, 359
Specular reflection, 320
Spherical aberration, 372; mirrors,
328
Spiral thermometer, 229
Spirit-level, 93
Springs, 95; intermittent, 154
Stable equilibrium, 46, 47
Standard candle, 317
Staubbach, 53
Steam boiler, 274; engine, 266, 272
Steel, 408
Steelyard, 23, 51
St. Elmo's fire, 460
Stereoscope, 397
Stethoscope, 170
Stills, 261
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