vi PREFACE. 
discussion of the theory of the seismograph, which is the first to appear in English. 
Accompanying this volume are many seismograms of the earthquake, which appear 
in the general atlas. These seismograms are records of the shock as registered at 
almost all the seismological stations the world over, and are published at the sug- 
gestion of the International Seismological Association for purposes of comparison with 
one another, to the end that the best recording devices may be generally adopted, 
and also for comparison with the similar series of seismograms of the Valparaiso earth- 
quake of August 16, 1906, which has been published by the Association. 
ANDREW C. LAWSON, 
Chairman State Earthquake Investigation Commission. 
BerkKELEY, May 31, 1908. 
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