On a summer's day in 1858, in a garden behind Christ Church College in Oxford, Charles Dodgson, a lecturer in mathematics, photographed six-year-old Alice Liddell, the daughter of the college dean, with a Thomas Ottewill Registered Double Folding camera, recently purchased in London. Simon Winchester deftly uses the resulting image--as unsettling as it is famous, and the subject of bottomless speculation--as the vehicle for a brief excursion...