Milestones: Oct. 1, 1965

Divorced. Alan Jay Lerner, 47, Broadway lyricist (Camelot, the upcoming On a Clear Day You Can See Forever); by Micheline Lerner, 37, his fourth wife; on grounds of mental cruelty; after nearly eight years of marriage, one child; in Las Vegas. Settlement: a reported $1 million.

Divorced. By Joan Bennett, 55, movie siren of the 1930s (Careless Lady): Walter Wanger, 71, veteran film producer (Joan of Arc, Cleopatra), who in 1952 served 15 weeks in jail for jealously shooting her agent, Jennings Lang, in the groin; on grounds of incompatibility; after 25 years of marriage, two children; in Juarez, Mexico.

Died. Michael Charles Boyer, 21, only son of Actor Charles Boyer, promotion director for his father's Valiant Record Company; by his own hand (.38-cal. pistol), in a game of Russian roulette after his fiancée broke off their engagement; in West Los Angeles.

Died. John Augustus Larson, 72, Canadian-born psychiatrist who, while doing research with the Berkeley, Calif., police force in 1921, correlated medical devices measuring skin temperature, blood pressure and breathing rate to develop the first lie detector; of a heart attack; in Nashville, Tenn.

Died. Arthur Holmes, 75, foremost British geologist, author of the classic textbook, Principles of Physical Geology, whose pioneering use of radioactivity as early as 1913 in determining the age of rocks paved the way for the geological time scale, which places the origins of the earth at 4.5 billion years; of uremic poisoning; in London.

Died. Othmar Hermann Ammann, 86, master bridge builder, a Swiss-born engineer who pursued a lifelong vision of graceful suspension bridges linking major U.S. arteries, designed and built New York's George Washington, Triborough and new Verrazano-Narrows bridges and played a major role in the construction of San Francisco's Golden Gate and Delaware's Memorial bridges; after a brief illness; in Rye, N.Y.

Died. John William Elmer Thomas, 89, long-term Democratic Senator from Oklahoma (1926-1950), and vociferous spokesman for the Senate's pro-inflation bloc who early in the Depression vainly waged a campaign to force unlimited currency upon the nation, thereafter remained a cantankerous critic of Administration policies from public power to Marshall aid, was finally defeated in the 1950 primary by Congressman Mike Monroney shortly after being exposed for trading in the cotton commodities market; of pneumonia; in Lawton, Okla.