WHAT IF Amerigo Vespucci had been named Ralph?

Except for the name on the money and the songs ("Ralph the Beautiful?") and a few other details, it probably wouldn't have made much difference, because Vespucci and Columbus were by no means the only Italians involved with the invention of America.

A new show of 79 early maps and rare books -- "The Italians and the Creation of America" -- has opened at the Museum of American History, to run through March. It's worth spending some time with.

One reason so many early explorers were Italians was that their city-republics had piled up considerable investment capital in the 12th and 13th centuries, the exhibit explains, and that the hazards of doing business outside their own independent cities had developed a particularly sharp type of person. Businessmen and others were trained to calculate quickly, observe and balance elements, judge shrewdly.

"These skills, the genius of Italy, permeated all levels of culture: They were as much a part of the manner in which Italians looked at paintings as they were of Italian methods of looking at new lands and new maps."

An interesting insight. You sense the alert, speculative mentality behind many of these maps. There is an Italian-made 1440 map based on Ptolemy, but it breaks with Ptolemy's beliefs on several points. It shows the Indian Ocean as an open sea, and it has Africa surrounded by water, a radical idea to hold even before Vasco Da Gama sailed the Cape of Good Hope.

It is fascinating to contrast the maps of the New World made through the 16th century Some earlier ones seem closer to reality than later ones. Knowledge had a way of "receding," as in the case of a Scandinavian map, which showed a much cruder understanding of the western North Atlantic than was common in Italy at the time. And this despite the Norse explorations.

Unknown lands and seas in this charming 1572 fantasy by Olaus Magnus are populated by mythical beasts and sea serpents. Even Britain, which surely would be well known to Scandinavians, one would suppose, turns up as an inchoate bunch of roundish islands. Some other map makers too seem to have had trouble with the craggy coast of Britain.It couldn't have been much fun to sail around.

One of the most elegant maps in this show loaned by the John Carter Brown Library in Providence is Vesconte Maggiolo's 1511 version of the world taken from a portolan atlas. These are sailors' atlases that show only the coastlines, with the port names written in perpendicularly. This one, an important early picture of America, does make a few little errors: It identifies North America with eastern Asia, and it has a terrible time with England, trying to run the Thames clear through to the Devon coast. But it does get the two Americas rather well. And the Red Sea is bright red.

There are other rarities and curiosities -- a heart-shaped map, for instance, and a 1493 edition of Columbus' story of his first voyage: the first instant book.

And then there is Zacharias Lilio, Bishop of Florence, whose book, published (in Latin, of course) hardly three years after Columbus came back, was decidedly skeptical about the whole thing "... unless anyone believes very extraordinary news that the King of Spain, so they say, is sending ships these days to explore new shores."