And David McCullough is not typing on a computer. He’s using the pre-digital dinosaur that requires a considerable force of those digits called fingers: the typewriter. Not even a zippy electric version, but a 1940s vintage Royal manual typewriter that he bought second-hand in the 1960s. So if you want to know how it is that David McCullough’s books always hit the New York Times bestseller lists, capture Pulitzers, and have never gone out of print, it just may be this old machine.