110 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



Francisco to San Diego. Its results may be stated in general 

 to show that along the entire coast of California a depth of 

 fifteen hundred fathoms or more is reached as soon as we go 

 westward to a distance of from twenty to seventy miles 

 from the shores. The greater part of this sudden fall occurs 

 in the last ten to fifty miles. At one hundred miles west of 

 San Francisco the bottom is over twenty-five hundred fath- 

 oms deep. The bed of the ocean continues of a uniform 

 depth greater than fifteen hundred fathoms until we reach 

 the Sandwich Islands, the greatest depth being three thou- 

 sand fathoms at a distance of about four hundred miles east 

 of Honolulu, which great depth is maintained until we reach 

 within ninety miles of Honolulu. At fifty miles from that 

 town the depth is fifteen hundred fathoms. The calcula- 

 tions made by Professor Bache in 1854, based on the move- 

 ments of the earthquake waves, gave an average depth of 

 from twenty-two hundred to twenty-five hundred fathoms. 

 The average depth of the present sounding is about twenty- 

 four hundred fathoms. The bottom is generally a soft yel- 

 lowish-brown ooze, and the temperature was every where 35 

 Fahrenheit. In all these soundings the steel wire recom- 

 mended by Sir William Thomson has been used, and, won- 

 derful to relate, the same wire has been used in the entire 

 work, and the apparatus still works excellently. The sound- 

 ings were made at an average distance of forty miles apart. 



CAEBONIC ACID IN ATMOSPHERIC AIR. 



In a paper by Truchot upon the proportion of carbonic 

 acid existing in atmospheric air, and its variation with alti- 

 tude, it is stated, first, that the proportion is a little greater 

 during the night than the day, amounting to about four vol- 

 umes in the ten thousand by day, and four and three tenths 

 by night, according to one determination, and to a little less 

 by another; second, that the proportion of carbonic acid is 

 not decidedly greater in the city than in the country, away 

 from the direct influence of vegetation ; third, that in the vi- 

 cinity of plants with green leaves in continual vegetation 

 the proportion of carbonic acid varies notably, whether the 

 green portion is illumined by the sun, or is in the shade, or 

 entirely in obscurity. 



In reference to variation with altitude, it is found that the 



