Rumors of Demise Not So Greatly Exaggerated.

It was here in the third-floor billiard room where America's greatest humorist used to hole up when the bustle of his house, and the nursery one flight below, became too great, leaving strict orders not to be disturbed. Seated at a desk tucked behind the billiards table, he wrote and rewrote in longhand such masterpieces as ''Huckleberry Finn,'' often beseeching his editors to stop cleaning up his language and restore the earthier vernacular he preferred. [ABSTRACT FROM PUBLISHER]