Out of Plato it is gathered that America is an island.

Homer, Strabo, Aristotle, Dionysius, Mela, Pliny, Pius, affirm the continent of Asia, Africa, and Europe, to be environed with the ocean.

I may therefore boldly say (though later intelligences thereof had we none at all) that Asia and the West Indies be not tied together by any isthmus or strait of land, contrary to the opinion of some new cosmographers, by whom doubtfully this matter hath been brought in controversy.

And thus much for the first part of my answer unto the fourth objection.
The second part, namely, that America and Asia cannot be one continent, may thus be proved:--"The most rivers take down that way their course, where the earth is most hollow and deep," writeth Aristotle; and the sea (saith he in the same place), as it goeth further, so is it found deeper.
Into what gulf do the Moscovian rivers Onega, Dwina, Ob, pour out their streams?
northward out of Moscovy into the sea.

Which way doth that sea strike?
The south is main land, the eastern coast waxeth more and more shallow: from the north, either naturally, because that part of the earth is higher, or of necessity, for that the forcible influence of some northern stars causeth the earth there to shake off the sea, as some philosophers do think; or, finally, for the great store of waters engendered in that frosty and cold climate, that the banks are not able to hold them.