Palmer, Col. H. S., on earth tremors, 307 Palmieri, on clock stopping, 36, 62 Paul, H. M., on earth tremors, 308 Perrey, A., on the influence of the moon on earthquakes, 251 Perrey on the periodicity of earthquakes, 8 Perry, J., on position of openings in walls, 111 Physicists, on the interest of earthquakes to, 2 Planets, influence of, on earthquakes, 260 Plantamour, M., on earth pulsations, 328 Pleistoseists, definition of, 10 Poly, M. A., on earthquakes and sun spots, 263 — on earthquakes and revolving storms, 294 Prost, M. le Baron, on earth tremors, 316 Pulsation, on earth, 4, 326–343 Records, on receivers of, 33 Rivers, on disturbances in, 154 Rockwood, Prof., on American earthquakes, 6 Ronaldson, T., on San Francisco houses, 129 Rossi, M. S. di, on an eruption of gas in the Tiber, 153 — aurora and earthquakes, 264 — earth tremors, 317, 320 — earth oscillations, 346 — earth pulsations, 327 — microseismograph of, 318 — microphonic observations of, 319, 323 — normal tromometer of, 317 Schmidt, on the influence of barometric pressure on earthquakes, 267 Sea waves, on nature of, 165 — on cause of, 171 — seldom produced by earthquakes which originate inland, 175 — on velocity of propagation of, 177 — examples of, 179 Seasons, frequency of earthquakes at different, 254 Seebach, on the determination of origins, 211 — on the focal cavity, 224 Seismic vertical, definition of, 9 Seismic and volcanic phenomena, relation of, 270 — — conclusions regarding, 275, 295 Seismology, definition of, 9 Seismometers, on various forms of, 17–40 Seismoscopes, on various forms of, 13–20 Serpieri, P. A., on distribution of seismic movement, 231 Shadows, on earthquake, 137 Spring, on frequency of earthquakes during, 156 Stukeley, on earthquake motion, 42 — earthquakes and aurora, 265 Succussatore, definition of, 10 Sun, on the effect of, on earthquakes, 253, 285 Temperature, effect of changes of, on earthquakes, 268, 294 Terremoto, definition of, 10 Thomson, Sir W., on the rigidity of the earth, 285 Time, on recording apparatus for, 35 Travagini, F., on earthquake motion, 42 Trembelores, definition of, 10 Tremors, on earth, 3, 306–325 Understanding, effects of earthquakes on, 2 Verbeck, on the ball and plate seismometer of, 31 Vibration, on the nature of earthquake, 12 Vorticose motion, on, 70 — definition of, 10 Wagener, on the pendulum seismometer of, 25 — vertical motion seismometer of, 33 — list of earthquakes, 76 Wave paths, definition of, 9 Waves, on the nature of earthquake, 55 — on the interference of, 138 Wells, on the effect of earthquakes on, 156 Wenthrop, on the New Zealand earthquake of 1855, 79 West, on the parallel motion seismometer of, 28 Winslow, on pulsations of the ocean, 334 Wolf, R., on earthquakes and sun spots, 263 Woodward, on earthquake motion, 42 Young, Dr. T., on earthquake motion, 43