Enough sail had to be carried to give the ship ample steerage way when the walls of rushing water passed us, for incredible as it may seem to those who have not had the experience, the waves of the sea run at a speed far greater than anything afloat that sails. The tidal wave, theoretical at least, must have a speed of one thousand miles per hour in order that the tides may follow the attraction of the moon and girdle the earth each twenty-four hours; some speed even in these days of rapid travel. Here we have a vertical translation of motion and not a horizontal shifting of water at that terrific speed. In the sea waves caused by wind friction, there is also simply a translation of up and down motion, except for the rearing crest; if the sea waves moved bodily it would be extremely dangerous to live near the seashore and the coasts would soon be worn away; also, ships would not dare venture upon the ocean.
This statement about the possible destructive effect of the sea waves were they to move bodily started one of the hottest arguments ever contested in the fo'c'sle of the Fuller. Tired and worn as we were, the greater part of an afternoon watch below was taken up in assailing my position. Australia could not see that I was right; even my staunch pal Frenchy doubted it. Finally I brought out my trusty "Wrinkles in Practical Navigation" by that sailor's friend, the late Captain S. T. S. Lecky, who added laurels to the name of the English merchant sailor that will never fade, and put them all to rout. The passage on Great Sea Waves is worth giving, and I here include it.
"The term 'Great Sea Wave' is used in contradistinction to 'Great Earth Wave,' which latter is the name given to the disturbance experienced on land.
"An earthquake may have its center of impulse either inland or under the bed of the ocean. In the first case, when the 'Great Earth Wave,' or superficial undulation, coming from inland, reaches the shores of the sea (unless these be precipitous, with deep water) it may lift the water up, and carry it out on its back, as it were; for the rate of transit of the shock is sometimes so great that the heap of water lifted up has not time to flow away toward the sides.
"At Arica, in Peru, and other places, this sudden going out of the sea has made bare the bottom of the bay, and left ships aground which only a few minutes before were riding quietly at anchor in several fathoms of water.
"As soon as the shock is over, the body of water thus forced out to sea returns as a huge wave, and, on approaching a sloping shore, rears up like a wall, and breaks with overwhelming force. Sometimes, however, its volume, height, and velocity are so great that it comes ashore bodily, and breaks far inland, causing even greater destruction to life and property. At Arica, the Wateree—a 'double-ender' belonging to the United States Navy—was carried inland quite a distance by the reflux, and remained as evidence for many years. If the writer's memory is not at fault, she was carried clean over the railway embankment.
"When the seat of the disturbance is beneath the ocean, the 'Great Sea Wave' rushes in upon the land as before—with this difference, that it is not preceded by the water retiring from the foreshore, as in the first case....
"About the most notable instance of a 'Great Sea Wave' occurred during the stupendous and ever-memorable eruption in August, 1883, which had for its center the Island of Krakatoa, in the Straits of Sunda. On this occasion the loss of life amounted to 37,000, caused chiefly by the sea waves, one of which attained the almost incredible height of 135 feet. Its effects were traced to all the principal tide gauges of the world, and were even observed at Havre, some 11,000 miles from the source of origin.
"A full account of this eruption, which was investigated in detail by committees and sub-committees of the Royal Society, comprising many of the leading scientists of the day, has been published in a volume of nearly 500 quarto pages, under the editorship of Mr. G. T. Symons. In this book every branch of the phenomenon and its effects have been most thoroughly dealt with, and is consequently well worth perusal."
What Captain Lecky has said may well cause us to pause and wonder how a "Great Sea Wave" would affect Coney Island of a hot Sunday in midsummer.