October 20, 2002 'American Ground': Reverse Engineering at Ground ZeroBy JEFFREY GOLDBERG t the very end of William Langewiesche's slim but powerful account of the dismantling of the wreckage of the World Trade Center comes a story that served, at least for me, as an antidote to the overwhelming saccharinity of the recent Sept. 11 commemorations -- that great ''emotional bath,'' as one television anchor put it. William Langewiesche AMERICAN GROUND Unbuilding the World Trade Center.By William Langewiesche. 205 pp. New York: North Point Press/ Farrar, Straus & Giroux. $22. Langewiesche tells of a visit he paid this spring to...