This accessible reference presents the evolution of concepts of time and methods of time keeping, for historians, scientists, engineers, and educators. The second edition has been updated throughout to describe twentieth- and twenty-first-century advances, progress in devices, time and cosmology, the redefinition of SI units, and the future of UTC.

Astrologers worldwide made the late Neil F. Michelsen's American Ephemeris series best sellers. In 2006, Rique Pottenger revised and updated Michelsen's earlier work with The New American Ephemeris for the 21st Century 2000-2100 at Midnight, complete with newly named planets Ceres and Eris, plus much more. Now, following the debut of the big full century book, astrologers will find this new, lightweight 14-year version a "must have!" In easy -to-scan 8.25 x 11 format, it has all the new features of its forerunner and even more. For each month you'll also find a daily Declination and Latitude Table and a detailed Daily Aspectarian. Both Ceres and Chiron are included in daily longitude positions, and in the aspectarian. In Declination and Latitude, Sun through Saturn (including Ceres) are given daily, with Chiron, Uranus, Neptune, Pluto, Pallas, Juno, Vesta and Eris in 5 day increments.