Tomalin (The Invisible Woman) solves the problem of preparing yet another biography of Jane Austen (1775-1817), a ""life of no event,"" by a familiar formula. At every turn, one meets ""may have,"" ""may be"" and ""might have."" A biographical boon is the large supporting cast. Tomalin takes 100 pages to get Austen to age 18 by filling in the pages with stories about her relatives and neighbors in Hampshire. An entire chapter is devoted to a single Austen letter--and because few of her letters survive, Tomalin suggests that in some years, in a letter-writing age, Austen wrote none whatsoever. Such apparent silences are suffused with hypotheses about her dreary existence during the long gaps between her teenage novelizing and her shrewd, mature works like Emma and Mansfield Park, which followed the much-delayed publication of Sense and Sensibility and Pride and Prejudice. Tomalin is strikingly sensitive, however, to Austen's life of social discomfort. In what is a very personal book, she often resorts to the first person, which fits the speculative approach. Photos not seen by PW. (Nov.) FYI: For reviews of two other Austen biographies published this year, see Jane Austen by Valerie Grosvenor Myer in Nonfiction Forecasts (March 10) and Jane Austen by David Nokes (July 7).