The cards in this book were inspired by the discovery in the New York Library of a set of playing cards made by Thomas Tuttell In the 17C. He was an English mathematical instrument maker, who designed the cards as a trade catalogue, each card describing a tradesman at work, a particular instrument or tool. They also served to advertise his workmanship and broad scientific knowledge. These pages describe scientists and some of their most important discoveries, all of which have in some way changed the world we live in.