§ 14-18. THE SEA AND THE ATMOSPHERE. 5 



knocked in her by striking on the bottom, and she was reduced 

 to a wreck. In the course of five minutes the water in the harbor 

 fell, it it said, from 23 to 3 feet, and the anchors of the ship were 

 laid bare. There was a great loss of life ; many houses were 

 washed into the sea, and many junks carried up — one two miles 

 — and dashed to pieces on the shore. The day was beautifully 

 fine, and no warning was given of the approaching convulsion ; 

 the barometer standing at 29.87 in., thermometer 68° ; the sea 

 perfectly smooth when its surface was broken by the first wave. 

 It was calm in the morning, and the wind continued light all 

 day. 



14. In a few hours afterward, at San Francisco and San Diego, 

 The propagation of ^hc tide-gaugcs showcd that several well-marked 

 Its waves. ^^^^ extraordinary waves had arrived off the coast 

 of California.* The origin of these waves, and those which de- 

 stroyed the town of Simoda, in Japan, and wrecked the Diana, 

 was doubtless the same. But where was their birthplace? Sup- 

 posing it to be near the coasts of Japan, we may, with the tide- 

 gauge observations in California and Mr. Airy's formulae, calcu- 

 late the average depth of the sea along the path of the wave from 

 Simoda to both San Erancisco and San Diego. 



15. Supposing the waves to have taken up their line of march 

 Their breadth and ^^^m somc poiut aloug the coast of Japan, the San 

 velocity. Francisco wave, having a breadth of 256 miles, had 

 a velocity of 438 miles an hour; while the breadth of the San 

 Diego wave was 221 miles, and its rate of travel 427 miles an hour. 



16. Admitting these premises — which are partly assumed — to 

 Averagedepthofthe ^^ corrcct, thcu, according to Airy's formula, the 

 North Pacific. avcragc depth of the North Pacific between Japan 

 and California is, by the path of the San Francisco wave, 2149 

 fathoms, by the San Diego, 2034 (say 2 J miles). 



17. At the temperature of 60°^ the specific gravity of average 

 Specific gravity of sca-watcr is 1.0272,f and the weight of a cubic foot 



sea-water. -g g^ QQ3 ^^^g^ 



18. With the barometer at 30 in. and the thermometer at 32°, 

 Of air. the weight of a cubic foot of dry atmospheric air is 



* Ex. Doc. No. 22, Senate, 1st sess. Sith Congress, p. 342. 



t Maury's Sailing Directions, vol. i. Sir John Herschel quotes it at 1.0275 for 



G2' 



