148 PROCEEDINGS OF THE CALIFORNIA 



Dr. Cooper -wished to know why an imported species of oyster 

 should grow so large when those native to this coast, planted under 

 the same conditions, were no larger than in an uncultivated state. 



Prof. Davidson said that true diamonds had been recently found 

 in Arizona. The specimens had been brought by prospecting 

 miners, among a great variety of minerals, including rubies, gar- 

 nets, etc. The miners, not knowing the diamond in the rough, had 

 thrown aAvay some large and valuable specimens. The largest 

 brought to this city will cut three carats, and according to the ex- 

 perience of Frontier, Pohlman and Bellemere, lapidaries, will be 

 worth about $500 when cut. This discovery developes another in- 

 dustry in our country. 



Prof. Davidson said, in making some computations of recent as- 

 tronomical and geodetic observations, large deflection of the plumb 

 line had been detected. Numerous instances were cited, from the 

 Straits of Fuca to Los Angeles, where the deflection ranged from 6 

 to 12 seconds of arc. But no prediction of the direction of the 

 deflection could be made from the position of adjacent mountains, 

 for although the Santa Barbara mountains evidently deflect the 

 plumb line li seconds, the deflection at Santa Cruz is 10 seconds 

 towards the deep submarine valley of Monterey Bay, although the 

 hills rise high to the northward of the station. At the Straits of 

 Fuca station, the error of deflection of the plumb line was 6 seconds ; 

 at San Francisco, 6 seconds ; at Santa Cruz, 10 seconds, not 

 towards the north line of mountains, but south, towards a submarine 

 valley in Monterey Bay, showing a powerful submarine attracting 

 power. 



Dr. Blake said that observations showed a connection between 

 our meteorology and that of the Sandwich Islands. A gale oc- 

 curred at the Islands on the 20th of October. The barometer in 

 San Francisco commenced falling on the 21st, and reached the mini- 

 mum on the 24th, in the morning. On the 27th a gale at the 

 Islands began, Avhich lasted three days. The barometer in San 

 Francisco fell 0.25 from the 29th to the 30th, the minimum being 

 reached November 2d. A gale blew at the Islands from October 

 30th to the 6th of November. The barometer in San Francisco 

 began to fall on the 4th, and reached its minimum on the 6 th. 



Dr. Le Plongeon read a lengthy paper on the origin of earth- 

 quakes. 



