190 PROCEEDINGS OF THE CALIFORNIA 



bluish white ; muscular scars large, the anterior triangular, posterior a third the 

 largest, broadly suboval. 

 A single fresh valve was found on the beach at Santa Cruz, Cal., by Dr. Cooper. 



Earthquakes in California during 1§64. 



BY DR. JOHN B. TRASK. 



Feb. 26th, h. 40 m.— A light shock of earthquake at San Francisco. At 

 5 h. 45 m. a smart shock, having three distinct vibrations. On the day previous, 

 an " Electric Storm " prevailed between Visalia, Tulare Co., and Los Angeles, 

 which was very violent in its effects on the telegraph lines. 



On the 27th, a heavy "Norther " commenced and continued till the eve of the 

 28th. 1 his earthquake was felt at San Jose, fifty imles south, at the same hour, 

 and was marked by tvvol very smart shocks following each other in quick succes- 

 sion. 



March 5th, 8 k. 49 m. — A smart shock of earthquake at San Francisco. The 

 earthquake began at the above hour. The first wave was in a direction north 

 and south, and lasted one and three-fourths seconds. Nearly one and a half 

 seconds elapsed before the second shock, which occured at forty-nine minutes, 

 three seconds past eight o'clock, and had a duration of one and one-half seconds. 

 The motion in this shock was rotatory. 



Magnetism was not suspended in this nor either of the other shocks, this year. 

 The total length of time included in this earthquake, was nearly 5 seconds These 

 observations were made at the height of 20 feet 4 inches above the ground, 

 but persons situated at a greater height felt the vibrations longer and more 

 severely. 



We have brief details of this earthquake from Santa Rosa, at the north, to Santa 

 Cruz at the south, and from Stockton at the east, for which we acknowledge our 

 obligations to the Telegraph Company, At Santa Rosa it occurred at 8 h. 50 m. 

 the shock was light. At Petaluma 8 h. 50 m., also light. At Stockton about 9 h., 

 shock was severe. At Santa Clara 8 h. 40 m., the shocks were very severe. The 

 church spires waved to and fro, and the earthquake is reported to have continued 

 over two minutes, with light vibrations between the heavier waves. At Santa 

 Cruz no time is given. 

 March 10th, 14 h. 8 m. — A light shock was felt in San Francisco. 



" " 16 h. 30 m. — Another shock at San Francisco, marked by two 

 distinct vibrations and lasting three and one-half seconds. 



March 20th, 23 h. 45 m. — A light shock of earthquake having four distinct 

 tremors, and occupying a little more than three seeonds. 



March 22d, 13 h. m. — A smart shock was felt at Stockton, causing some 

 little commotion. 



May 20th, 18 h. 1 m.— A light shock of earthquake at San Francisco. At 

 Stockton the shock was quite severe and occurred nine minutes later. At San 

 Jose it also was very sharp. At Napa the earthquake, which was quite severe at 



