Why the American Aborigines are called Indians

I have often wondered how the aborigines of America came to be called Indians; and for a considerable time I presumed it to be a popular appellation arising from their dark colour. Lately, however, I fell in with a copy of *Theatrum Orbis Terrarum*. Antwerp, 1583, by Abraham Ortelius, geographer to the king; and, in the map entitled *Typus Orbis Terrarum*. I find America called *America, sive India Nova*. How it came to get the name of *India Nova* is of course another question, and one which at present I cannot answer.