On the desktop is a charming photo sent by a reader. It shows former House speaker Joseph Cannon, then still an active member of Congress from Illinois, celebrating his 84th birthday on May 7, 1920, with a half dozen old congressional friends. And we do mean old. All were in their seventies or eighties. All but one were in their eighties upon later retirement or death.

It's a far cry from both houses of today's remarkably youthful Congress, in which just one octogenarian serves -- Rep. Claude Pepper of Florida, who recently turned 85. Pepper first came to Washington as a 36-year-old senator in 1936.

On noting the milestone in Pepper's life, we asked readers if they knew who was the oldest person to serve in Congress. Our guess was Sen. Theodore Francis Green of Rhode Island who, still spry, retired at age 93 years 3 months (in numerical shorthand, 93-3) in 1961.

That query brought a reply from L. Robert Davids of Washington, who confirmed Green's record and sent along an article he wrote on congressional longevity in 1964 for Roll Call, the Capitol Hill weekly newspaper.

Green was 87-1 when elected to his final term on the Hill. But one of Cannon's birthday party companions, Rep. Charles M. Stedman of North Carolina, was eight months older when he ran for his 10th and final House term in 1928. He died in 1930 at the age of 89-8, the oldest member of Congress to die in office.

Cannon retired at 86-10 in 1923, having served since 1873, with two interruptions.

Here, courtesy of reader Davids, are the top 15 elders ever to have served in Congress, with states, ages and the years they left office:

Sen. Green, 93-3, 1961; Rep. Stedman, 89-8, died 1930; Rep. Isaac Sherwood, Ohio, 89-7, 1925; Rep. Robert Doughton, North Carolina, 89-2, 1953; Sen. Justin Morrill, Vt., 88-8, died 1898; Sen. Carter Glass, Va., 88-5, died 1946; Rep. Brent Spence, Ky., 88-0, 1963; Sen. Rebecca Felton, Ga., 87-5, 1922; Rep. Clare Hoffman, Mich., 87-4, 1963; Sen. Andrew Houston, Texas, 87-0, died 1941; Rep. Cannon, 86-10, 1923; Sen. Carl Hayden, Ariz., 86-8, 1969; Rep. Adolph Sabath, Ill., 86-7, died 1952, and Rep. Joseph Mansfield, Texas, 86-5, died 1947.

A footnote: Sen. Felton, the wife of a former House member, was the first woman to serve in the Senate, by appointment to fill an unexpired term. She attended only two days of sessions before her elected successor claimed the seat.