Vili CONTENTS. 
PERIODS AND AMPLITUDES. : 
During the Preliminary Tremors . : 
During the Long Waves and the Principal Part : 
In the Megaseismic District 
Beyond the Megaseismic District . 
MAGNETOGRAPH ReEcorps . 
CoNCLUSIONS 
Time 5 
Undamped Teeuommente 5 
Damped Instruments 
Period of the Pendulum 
Magnifying Power for Short Periods 
Time-scale : : 
Identification of the Bier on aes (Beiamnooracas : 
APPENDIX. 
THEORY OF THE SEISMOGRAPH. 
INTRODUCTION 
RoTATIONS DUE TO EARTH WAVES . 
ForMs OF SEISMOGRAPHS 
REGISTRATION 
THe MATHEMATICAL THEORY 
Tue HorizontaL PENDULUM 
Determination of the Constants 
Interpretation of the Record . 
Magnification of Harmonic Disturbances 
Maximum Magnifying Power : 
Suspensions of Horizontal Pendulums . 
THE VERTICAL PENDULUM 
THe INVERTED PENDULUM 
SEISMOGRAPHS FOR VERTICAL MOVEMENTS 
SEPARATION OF LINEAR DISPLACEMENTS AND TILTS 
DEFINITIONS . 
UsreruL ForMULz 
PLATES. 
PLATE 
1. Map showing Distances and Directions from the Origin of the Shock . 
2. Hodographs of the California Earthquake 
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