Now, one day this star-fish set out on a summer journey,—­not to the seaside where you and I went last year:  of course not, for he was there already.  No; he thought he would go to the mountains.  He could not go to the Rocky Mountains, nor to the Catskill Mountains, nor the White Mountains; for, with all his accomplishments, he had not yet learned to live in any drier place than a pool among the rocks, or the very wettest sand at low tide:  so, if he travelled to the mountains, it must be to the mountains of the sea.

Perhaps you didn’t know that there are mountains in the sea.  I have seen them, however, and I think you have, too,—­at least their tops, if nothing more.  What is that little rocky ledge, where the lighthouse stands, but the stony top of a hill rising from the bottom of the sea?  And what are the pretty green islands, with their clusters of trees and grassy slopes, but the summits of hills lifted out of the water?

In many parts of the sea, where the water is deep, are hills and even high mountains, whose tops do not reach the surface; and we should not know where they are, were it not that the sailors, in measuring the depth of the sea, sometimes sail right over these mountain-tops, and touch them with their sounding-lines.

The star fish set out one day, about five hundred years ago, to visit some of these mountains of the sea.  If he had depended upon his own feet for getting there, it would have taken him till this day, I verily believe; but he no more thought of walking, than you or I should think of walking to China.  You shall see how he travelled.  A great train was coming, down from the Northern seas; not a railroad train, but a water train, sweeping on like a river in the sea.  Its track lay along near the bottom of the ocean; and above you could see no sign of it, any more than you can see the cars while they go through the tunnel under the street.  The principal passengers by this train were icebergs, who were in the habit of coming down on it every year, in order to reduce their weight by a little exercise; for they grow so very large and heavy up there in the North every winter, that some sort of treatment is really necessary to them when summer comes.  I only call the icebergs the principal passengers, because they take up so much room; for thousands and millions of other travellers come with them,—­from the white bears asleep on the bergs, and brought away quite against their will, to the tiniest little creatures rocking in the cradles of the ripples, or clinging to the delicate branches of the sea-mosses.  I said you could see no sign of the great water train from above:  that was not quite true, for many of the icebergs are tall enough to lift their heads far up into the air, and shine with a cold, glittering splendor in the sunlight; and you can tell, by the course in which they sail, which way the train is going deep down in the sea.