Corbett's history of bridges and bridge builders, from the first felled trees and vine cables through the keystone arch, triangle truss, and record-breaking suspension spans, is a comfortable mix of apt anecdote, biographical sketch, engineering principle and progress, and suggestive commentary. (Regarding railroad bridge builder Robert Stevenson's creative problem-solving, ""It is always worthwhile to imagine the impossible and to consider it from all angles. . . ."") Corbett ranges smoothly between well-chosen incidentals--on the fashionable prefab Nonesuch House assembled on Old London Bridge, or the purchase in 1968 of New London Bridge by the developer of Lake Havasu City, Arizona, so the town (sporting an imitation English village) could have a ""focus""--and more central concerns such as the brilliant innovations and day-to-day problems of James Eads (who spanned the Mississippi) and the Roeblings (Brooklyn Bridge). And, for a historical handle on shoddiness, Corbett reports that in the 1870s ""America was a land of rickety bridges built by railroad companies more interested in profits than safety, or by shady contractors who cheated on the highway bridges they threw together. . . . One in every four eventually collapsed, an average of 40 per year. In most cases there was loss of life."" This, though, is solidly constructed, with no extra weight--and illustrated with flair.