Earthquakes on Pacific Coast.— Holden, 



Plate III. 



=^^^1 



Complete Three-Component Seismograph, for Motions in all Directions. 



The three pens are steady during a shock, while the glass plate moves to and fro 

 with the earth, and at the same time is made to rotate by the clock (at the left hand 

 in the cut). The steady pens mark the components of the earth's motions on the 

 smoked surface of the revolving plate. 



