'4 THE PHYSICAL GEOGRAPHY OF THE SEA. 



11. In very shallow pools, where the water is not more than a 

 Reirtfciou between ita few inches deep, the ripples or waves, as all of us, 



•depth and the waves . t -i i i i i -ii i • 



of the sea. when children, have observed, are small ; their mo- 



tion, also, is slow. But when the water is deep, the waves are 

 larger and more rapid in their progress, thus indicating the exist- 

 ence of a numerical relation between their breadth and their ve- 

 locity, and the depth of the water. It may be inferred, therefore, 

 that if we knew the size and velocity of certain waves, we could 

 compute the depth of the ocean. 



12. Such a computation has been made, and we have the au- 

 Airy's tables, thority of Mr. Airy,* the Astronomer Royal of En- 

 gland, that waves of given breadths will travel in water of certain 

 depths with the velocities as per table : 



13. Accident has afforded us an opportunity of giving a quasi 

 The earthquake of practical application to Mr. Airy's formulae. On 

 simoda. ^^^^ 23d of December, 1854, at 9.45 A.M.,t the first 



shocks of an earthquake were felt on board the Russian frigate 

 " Diana," as she lay at anchor in the harbor of Simoda, not far 

 from Jeddo, in Japan. In fifteen minutes afterward (10 o'clock), 

 a large wave was observed rolling into the harbor, 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 an- 

 other, and when the two receded — which was at lOh. 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 



* Encyclop. Metropol. 



t Notes of a Russian OflBcer, p. 97, No. 2 (Feb. 1856), vol. xxv., Nautical Maga- 

 zinCf London. 



