How to Measure a Cheshire Grin?

John Allen Paulos in the New York Times Book Review:

Charles Lutwidge Dodgson, better known as Lewis Carroll, was a mathematician at Oxford University for most of his life. His fanciful “Alice’s Adventures in Wonderland” and “Through the Looking Glass” are quite familiar to us, as, to a lesser extent, are his photographs of young children. In “Lewis Carroll in Numberland,” the distinguished British mathematician Robin Wilson has filled a perceived gap in the writings about Carroll by describing in a straightforward, jabberwocky-free fashion the author’s mathematical accomplishments, both professional and popular.

Wilson begins this fine mathematical biography with an account of Dodgson’s idyllic North England childhood. Born in 1832, the eldest son in a large family, Dodgson was mathematically gifted like his clergyman father. He read widely, wrote amusing pamphlets for his siblings and dazzled his teachers. As Wilson documents, some of Dodgson’s later concerns with logic, time and puzzles were already apparent in his pamphlets and letters.

Proceeding linearly through Dodgson’s life, Wilson pays particular attention to his early career at Oxford, including the sometimes tedious details of exams, classes and the tutoring of fellow students. But even at the beginning of his career, Dodgson demonstrated a playful approach to mathematics, frequently injecting little puzzles into his lessons. (One of his classics: A cup contains 50 spoonfuls of brandy, and another contains 50 spoonfuls of water. A spoonful of brandy is taken from the first cup and mixed into the second cup. Then a spoonful of the mixture is taken from the second cup and mixed into the first. Is there more or less brandy in the second cup than there is water in the first cup?)

More here.