He had seen the sailors running up and down, and it looked as easy as mounting a ladder; but the slackness of the ratlines--which, as the sailor told him, was the name of the pieces of rope which answered to the rounds of a ladder--made it at first awkward.

When they reached the main top the sailor told him to sit down, and look round quietly, till he became accustomed to the height.
"It looks unnatural and risky, at first," he said; "but when you get accustomed to it, you will feel just as safe, when you are astraddle the end of a yard, and the ship rolling fit to take her masts out, as if you were standing on the deck." As Reuben had heard the sailors laughing and joking aloft, as they hauled out the earrings of the sails, he had no doubt that what the sailor said was true; but it seemed, to him, that he should never accustom himself to sit at the end of a spar, with nothing but the water at a vast depth below.

It would be bad, even with the ship lying quiet, as at present.

It would be terrible with the vessel in a heavy sea.
The sailor now told him the names of the masts and stays, giving him a general idea of the work aloft, and presently asked him whether he would like to return to the deck now, or to mount a bit higher.

Although Reuben was now becoming accustomed to the position, he would, had he consulted his inner feelings, have rather gone down than up; but he thought it was better to put a good face on it, and to accustom himself, at once, to what he would probably have to do sooner or later.
Holding on tight then, and following the instructions of his companion, he made his way up until he was seated on the cap of the top-gallant mast, holding tight to the spar, which towered still higher above him.