In his previous books, Henry Petroski has initiated us into the hidden mysteries of such everyday artifacts as the lead pencil, the paper clip, the zipper, and the Post-it note.

Now, with Engineers of Dreams, he makes a jump in scale to contemplate those "dry paths" across the rivers and inlets of our cities, those "hard crossings" over the gulches and ravines of our countrysides, those eminently practical but inescapably aesthetic edifices that persist in taking our breath away (when we're not taking them for granted): bridges.

The great era of American bridge building - which from the 1870s through the 1930s gave us such landmarks as the Eads Bridge across the Mississippi, the Hell Gate Bridge across the East River, the George Washington Bridge across the Hudson, and the Golden Gate Bridge at the mouth of San Francisco Bay - called for a special breed of engineer: equal parts dreamer, inventor, and entrepreneur.

Since the building of any bridge is necessarily a collaborative effort, engineers of dissimilar philosophies and all-too-similar egos were thrown together on project after project, making for an ongoing, interwoven human and technological drama.