It is only in a country where newness and change and brevity of tenure are the common substance of life," wrote Henry James, "that the fact of one's ancestors having lived for a hundred and seventy years in a single spot would become an element of one's morality." Newness and rootedness are the twin poles of Sight-Readings, Elizabeth Hardwick's brilliant new collection of essays. (Her first, Seduction and Betrayal, was nominated for the National Book Award.) Hardwick's focus here is on American writers, at home and abroad, and especially women, as writers and as characters: Edith Wharton, Djuna Barnes, Gertrude Stein, Mary McCarthy, Elizabeth Bishop, Katherine Anne Porter, and Joan Didion, among others.        In sections on Old New York, Americans Abroad, and Fictions of America, Hardwick considers writers and their landscapes, real and imagined. Her essays on Edith Wharton and Henry James illuminate aspects of their inventions of New York. From there she takes us to the Paris of Gertrude Stein and Djuna Barnes, into the hermetic world of Boston Transcendentalism, and on to the suburbs of John Cheever, the America of Philip Roth and John Updike, and the restless expanses of Richard Ford and the Prairie poets.         Elizabeth Hardwick has achieved a permanent place in American letters for her sharp and elegant criticism. Her essays on American writers are them-selves a work of literature. Read Less