The next day Pauline and her brothers visited the wreck, and here new difficulties met them, for although the vessel lay hard and fast on the rocks, there was a belt of water between it and the main shore, which was not only broad, but deep.

 

“I can easily swim it,” said Dominick, beginning to pull off his coat.

 

“Dom,” said Otto, solemnly, “sharks!”

 

“That’s true, my boy, I won’t risk it.”

 

He put his coat on again, and turned to look for some drift-wood with which to make a raft.

 

“There’s sure to be some lying about, you know,” he said, “for a wreck could hardly take place without something or other in the way of spars or wreckage being washed ashore.”

 

“But don’t you think,” suggested Otto, “that the men whose graves we have found may have used it all up?”

 

Otto was right. Not a scrap of timber or cordage of any kind was to be found after a most diligent search, and they were about to give it up in despair, when Pauline remembered the bay where they had been cast ashore, and which we have described as being filled with wreckage.

 

In truth, this bay and the reef with its group of islands lay right in the track of one of those great ocean currents which, as the reader probably knows, are caused by the constant circulation of all the waters of the sea between the equator and the poles. This grand and continuous flow is caused by difference of temperature and density in sea-water at different places. At the equator the water is warm, at the poles it is cold. This alone would suffice to cause circulation—somewhat as water circulates in a boiling pot—but other active agents are at work. The Arctic and Antarctic snows freshen the sea-water as well as cool it, while equatorial heat evaporates as well as warms it, and thus leaves a superabundance of salt and lime behind. The grand ocean current thus caused is broken up into smaller streams, and the courses of these are fixed by the conformation of land—just as a river’s flow is turned right or left, and sometimes backward in eddies, by the form of its banks and bottom. Trade winds, and the earth’s motion on its axis, still further modify the streams, both as to direction and force.

 

It was one of those currents, then, which flowed past the reef and sometimes cast vessels and wreckage on its shores.

 

Hastening to the bay, they accordingly found enough of broken spars and planks, to have made half a dozen rafts, twice the size of that required to go off with to the wreck; so to work they went at once with eager enthusiasm.

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