TIME AFTER TIME

We probably won't be the only ones to feel disappointment when the subject of animals ""inner clocks"" gives way to the rotation of the earth and moon, and a short history of measuring time from the simple shadow stick we can make ourselves to today's atomic clock. But like Berger's Storms and Stars, this presents very basic explanations in the context of some more challenging, but unanswered, observations and some mind-stretching questions (""When did time begin? . . . what is the smallest unit of time?""). A likely first step beyond telling time.