(3) 4-6 Illustrated by Raúl Allén. Though it was commonly believed to be true, scientists couldn't prove with certainty that the earth turned on its axis--until Léon Foucault revealed his astonishing pendulum in 1851 Paris. Mortensen describes not only Foucault's early life and scientific work, but also the history of the physics question at hand. Allén's illustrations, by turns shadowy and luminous, amplify the drama of the biographical tale.

Reviewer: Katrina Hedeen