This heaping helping of information (2,318 pages) may not be the most affordable ($125) or up-to-date reference going ('Mars,' for instance, is lacking information on the controversial fossil-microbe meteorite), but it is nonetheless comprehensive (7,800 articles and 1,200 biographies), authoritative (19 Nobel Prize winners are among the hundreds of contributors), attractive and easy to use. McGraw-Hill has crunched its most recent 20-volume science encyclopedia into a single volume, its 4th-edition Concise Encyclopedia of Science & Technology. Although Bridging has the feel of a self-published summer-vacation photo album and contains little about how bridges work, it does document a stunning diversity of designs while delivering tons of, pardon the expression, drop-dead gorgeous spans such as Italy's Treponti (circa 1634). Robert Cortright offers his second collection of bridge photography titled Bridging, this one distinguished from his 1994 work by the subtitle Discovering the Beauty of Bridges (Bridge Ink, $29.95). Check Odenwald's superb Web site for a preview of the question-and-answer format of the book.

It's also an honest career guide for anyone considering astronomy as a profession.

Odenwald, a scientist who loves his work. The Astronomy Cafe (Freeman, $14.95) is bedtime reading for stargazers from Sten F. Such now-classics as Basin and Range and Rising from the Plains are assembled here with more recent material on the midcontinent and together constitute a literary geological record that echoes the grandeur of McPhee's subject. For a whole that is greater than the sum of its parts, see John McPhee's latest, Annals of the Former World (Farrar, Straus & Giroux, $35), an epic compilation of McPhee's writings over the past 20 years on the North American continent's formation.

Impossibility by John D. Barrow