He admits outright to his own surprise at a researcher's exclamation over a "beautiful" experiment. The novelty of the assertion led him to query many scientists on which experiments might be so considered. The responses both surprised and gratified him. The result of his survey is this excellent book. The ten selected range from the means to first measure the earth to the realization that electrons can be in two places at once. A combination of good science and fine writing, coupled with an astute historical sense make this book a treasure.

What makes an experiment "beautiful"? Crease sets three criteria: depth, efficiency and definitiveness. "Depth" implies something fundamental about the world is revealed by the experiment. Certainly, measuring the globe using shadows in sunlight qualifies that criterion. "Efficiency" means the result is general enough to preclude having to do the experiment in a different manner to gain the same results. "Definitiveness" suggests that anyone can understand both the experiment and its value. Clearly, his ten choices show how these criteria work. Following the descriptive essay, Crease then explains the "beauty" aspect of it in the appropriate scenario, whether music, graphic art or theatre.

Of the ten, the two of the title are symbolic: Newton's breakdown and recombination of sunlight with prisms and Foucault's use of a pendulum to verify the Earth's rotation. Newton's demonstration has probably been castigated by the humanities more than anything else in science. "Unweaving the Rainbow" was the causus belli of the Victorian Romanticists their assault on science. Crease readily dismisses such obscurantism in explaining how valuable an exercise Newton's analysis of light proved. By extending the experiment from breaking down light to recombining it, Newton showed how research, like creating a painting, must reach beyond first results. There is, Crease notes, even a moral lesson in the exercise.

Foucault's pendulum conveys a reality about our world we cannot perceive otherwise. Awed by the realization that only our planet's rotation can force the pendulum to describe a circle while swaying from its mount, Crease applauds the teachers who bring their students to observe it. The experience is so profound, Crease describes it as a manifestation of "sublime beauty". It is clearly an experiment beyond an exercise in either pure mechanics or reasoning. Seeing the swinging orb successively tumbling a set of pegs forces a reconsideration of how we perceive the universe. What else, he asks, might greater perception have in store? This book challenges all who feel their perception of either science or beauty is complete. It is a worthwhile read for anyone asking, at any level, about the world they inhabit. [stephen a. haines - Ottawa, Canada]