by THOMAS GAVIN
398 pages. Random House. $10.
In 1826 a German flimflam man named Johann Nepomuk Maelzel appeared in the U.S. and began wowing the natives with his traveling show of mechanical marvels. His treasures included an automated trumpet player, a device called the panharmonicon that could duplicate the sound of a 40-piece orchestra (playing Beethoven) and an elaborate diorama showing the burning of Moscow. But Maelzel's star attraction was a hoax: a chess automaton nicknamed the Turk that took on all comersand was every bit as talented as the human player...