Page:Physical Geography of the Sea and its Meteorology.djvu/31

Rh first shocks of an earthquake were felt on board the Russian frigate "Diana," as she lay at anchor in the harbour of Simoda, not far from Jeddo, in Japan. In fifteen minutes afterwards (10 o'clock), a large wave was observed rolling into the harbour, and the water on the beach to be rapidly rising. The town, as seen from the frigate, appeared to be sinking. This wave was followed by another, and when the two receded—which was at 10h. 15m.—there was not a house, save an unfinished temple, left standing in the village. These waves continued to come and go until 2.30 P.M., during which time the frigate was thrown on her beam ends five times. A piece of her keel 81 feet long was torn off, holes were 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 harbour fell, it is 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 inland—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 58°; 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. The propagation of leaves by it.—In a few hours afterwards, at San Francisco and San Diego, the tide-gauges showed that several well-marked and extraordinary waves had arrived off the coast of California. The origin of these waves, and those which destroyed the town of Simoda, in Japan, and wrecked the "Diana," was doubtless the same. But where was their birthplace? Supposing it to be near the coasts of Japan, we may, with the tide-gauge observations in California and Mr. Airy's formulæ, calculate the average depth of the sea along the path of the wave from Simoda both to San Francisco and San Diego.

15. Their breadth and velocity.—Supposing the waves to have taken up their line of march from some point along the coast of Japan, the San 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. Average depth of the North Pacific.— Admitting these premises—which are partly assumed—to be correct, then, according