But Columbus finally removed any lingering doubt, yes? Well, as the rest of the book shows, there have been people who thought the world was flat even in recent times, in fact the idea had something of a resurgence in the 19th Century. We hear of the publications of 'Parallax' and of the wager between John Hampden (who argued for a flat earth) and Alfred Russell Wallace - Wallace won, but still found himself hundreds of pounds out of pocket. Into the 20th century there was Lady Blount, Zion City and even into the space age there were those who seriously believed the earth was flat (as well as many who weren't so serious).
The book is well researched and a entertaining read. I found that it gives a valuable insight into some people fixate on an idea and won't recognise any evidence against it - and of the problems of trying to argue with such people.