TWAIN, Mark (1835-1910). A onetime printer and Mississippi River boat pilot, Mark Twain became one of America's greatest authors. His 'Tom Sawyer', 'Huckleberry Finn', and 'Life on the Mississippi' rank high on any list of great American books. Mark Twain was born Samuel Langhorne Clemens on Nov. 30, 1835, in the small town of Florida, Mo. He was the fourth of five children.

His father was a hard worker but a poor provider. The family moved to Hannibal, Mo. , on the Mississippi, when young Clemens was 4 years old. It was in this river town that he grew up, and from it he gathered the material for his most famous stories. The character of Judge Carpenter is somewhat like his father; Aunt Polly, his mother; Sid Sawyer, his brother Henry; Huck Finn, a town boy named Tom Blankenship; and Tom Sawyer, a combination of several boys -- including himself. His father died when he was 12, and the boy was apprenticed to a printer.

An apprentice works for someone in order to learn a trade. This was the first step toward his career as a writer. In 1857 he apprenticed himself to a riverboat pilot. He became a licensed pilot and spent two and a half years at his new trade. The river swarmed with traffic, and the pilot was the most important man aboard the boat. He wrote of these years in 'Life on the Mississippi'.

The Civil War ended his career as a pilot. Clemens went west to Nevada and soon became a reporter on the Virginia City newspaper. Here he began using the pen name Mark Twain. It is an old river term meaning two fathoms, or 12 feet (4 meters), of water depth.

In 1864 he went to California. The next year he wrote his 'Jumping Frog's tory, which ran in many newspapers. He was sent to the Sandwich Islands (now Hawaii) as a roving reporter, and on his return he began lecturing. He was soon on a tour of the Mediterranean and the Holy Land. From this came 'The Innocents Abroad', which made him famous.

In 1870 he married Olivia Langdon. She modified Twain's exaggerations, sometimes weakening his writings, sometimes actually making them more readable. Twain began turning out a new book every few years. William Dean Howells, editor of the Atlantic Monthly and a highly respected novelist, became his close friend and literary adviser. Twain bought a publishing firm in Hartford, Conn. He earned much money writing, lecturing, and in his publishing house, but he spent it on high living and unsuccessful investments.

He lost a fortune promoting a typesetting machine. By 1894 his publishing company had failed and he was bankrupt. Twain set out on a world lecture tour to retrieve his fortune, and by 1898 his debts were paid. In his last years he traveled and spoke much but wrote comparatively little. He died on April 21, 1910. Twain was more than a humorist.

Behind his mask of humor lay a serious view of life. Tragedy had entered his own life in the poverty and early death of his father, the loss of a daughter, and his bankruptcy. His short story, 'The Man That Corrupted Hadleyburg', published in 1900, which showed greed at work in a small town, is an indication of Twain's dark side. The controversial 'Huckleberry Finn', which is periodically banned in schools or libraries because of alleged racial overtones, can be read by children, but it is not a child's book. It has elements of heartbreak and wisdom that can be appreciated best by adults.

On the other hand, 'Tom Sawyer' is primarily a juvenile book but one that can be read with pleasure by adults. Twain's chief works are: 'The Celebrated Jumping Frog of Calaveras County', a collection published in 1867; 'The Innocents Abroad' (1869); 'Roughing It' (1872); 'The Gilded Age' -- with Charles Dudley Warner (1873); 'The Adventures of Tom Sawyer' (1876); 'A Tramp Abroad' (1880); 'The Prince and the Pauper' (1882); 'Life on the Mississippi' (1883); 'The Adventures of Huckleberry Finn' (1884); 'A Connecticut Yankee in King Arthur's Court' (1889); 'The Tragedy of Pudd'n head Wilson' (1894); and 'Personal Recollections of Joan of Arc' (1896). Printed posthumously were: 'The Mysterious Stranger' (1916); 'Mark Twain's Notebook' (1935); and 'Autobiography' (1959). FURTHER RESOURCES FOR MARK TWAIN Blair, Walter.

Mark Twain and Huck Finn: 1855-1873 (Univ. of Calif. Press, 1974). Clemens, Cyril. Young Sam Clemens (Foxcroft, 1977). Clemens, Susy.

Papa: An Intimate Biography of Mark Twain by His Daughter Susy, Age 13 (Doubleday, 1985). De Voto, Bernard. Mark Twain's America (Univ. Press of Idaho, 1985).

Emerson, Everett. The Authentic Mark Twain (Univ. of Pa. Press, 1985). F revert, P.

D. Mark Twain, an American Voice (Creative Education, 1981). Hargrove, Jim. Mark Twain (Children's, 1984). Kaplan, Justin. Mr.

Clemens and Mark Twain (Simon & Schuster, 1983). Excerpted from Compton's Interactive Encyclopedia Copyright (c) 1994, 1995, 1996, 1997 The Learning Company, Inc. All Rights Reserved.