The New World in an old map, explained at Hingham library

At the heart of Toby Lester’s book “The Fourth Part of the World” is the Waldseemüller world map of 1507, which gave the New World the name of America and showed that it was a separate continent. Explaining how the map came into existence required Lester to move back five centuries.

Lester wrote about the map for the Boston Globe last fall, and this Sunday at 2 p.m., he’ll present a slide show and speech at the Hingham Public Library. A Belmont resident who lived in Scituate for several years as a child, Lester is a contributing editor to the Atlantic. He recently spoke with the Globe about writing the book.

I had been an editor and writer for the Atlantic about a decade and had written some substantial articles, but never anything on the history of maps. The Library of Congress has put out a press release in 2003 announcing they had bought the map for $10 million, and that got my attention. It got me interested in why I hadn’t heard about the map, and what the story of the map was. When I started looking into that, I got more and more interested in the subject, and it expanded and expanded.

It was an amazing multidisciplinary project. There was a stunning number of areas that I have to get up to speed on, pretty much from scratch: the history of cartography; the history of geographical exploration; the history of the Age of Discovery, the Middle Ages, the Renaissance and humanism; the history of the printing press and the diffusion of the book; it just goes on and on....

It’s like a spider at the center of a web. You can walk out along any one of the strands and find yourself in a completely new and interesting place, and then come back to the center.

One fun element of the story is the way America got its name. It was coined by two forgotten German humanists (Martin Waldseemüller and Matthias Ringmann) in the mountains of eastern France....They were also the first to understand, or guess, that the New World has not a part of Asia, which is what Columbus went to his grave believing, and others like Amerigo Vespucci thought.

At the Hingham library, I’m going to do a slide show of digital images, and I’m not going to focus just on the map. I’m going to go back in time and show a lot of Medieval and Renaissance charts and maps and diagrams, and gradually show how they came together in the one big Waldseemüller map.

There are people who like history, and there’s a subcategory of people who really love maps. But what I’ve learned from my book tour is that almost everybody loves old maps. They’re kind of mesmerizing.