"You'll find me a curiosity," said the old man, standing up politely to greet a visitor. "I'm almost 100 years old. I can think well, If I could see well, I think I'd get married again."

David Pelton Moore, for decades a Washington patent lawyer and inventor, was born Nov. 5, 1877, in the family home just a few blocks from the White House on Pennsylvania Avenue NW. His father, a doctor, told him to used to chat with Abraham Lincoln on occasional strolls down the avenue.

The old home is going now. Moore has survived his 10 brothers and sisters, three wives, clients and old friends. Yet he remains lively, a natty dresser who sports a waxed moustache, a man of charm and wit, own initiative, typed out a $1 billion claim infringing his patent on an explosive and rocket propellent.

That is a story that spans three-quarters of a century and is continuing in the U.S. Court of Clains today. It has brought Moore once again into the fray of current events as he gathers about himself lawyers and new friends who are helping him in his suit.

They are preparing, also for Moore's own private centennial celebration - a gala birthday party on Nov. 5 in honor of a man whose life has covered and intimately touched such a great span of American history and the history of this city.

As a child, Moore used to play near the Washington Monument when it was still half built. One of his grandfathers, Thomas Prettyman, came here from England in 1780 when Thomas Jefferson was President. Later, Moore said, Prettyman was captured during the War of 1812, and imprisoned on a ship with Francis Scott Key, who composed "The Star-Spangled Banner" during that period.

"My father was a druggist and a doctor, and we lived over the store," said Moore. "When the inaugural parades went by we watched them from the front porch."

He remembers watching the inauguration parades of Grover Cleveland in 1885 and of Benjamin Harrison in 1889 in this way. "Both days were beautiful days, the first of January. Cleveland was the first President I shook hands with. I was 8 years old then. I looked up in his face - he was supposed to be so handsome - and it was covered with pock marks!"

Moore recalls the smallest details of his attendance at various Washington elementary schools before the turn of the century - how beautiful was Miss Thompson, his fourth-grade teacher; how he was the teacher's pet in the fifth grade.

Moore enjoyed chemistry at Washington's old Central High School, and that interest remained with him after he graduated in 1899 with an M. A. in patent law from Columbian University (now George Washington University). He began tinkering seriously with explosive powder in 1901, and he still remembers vividly the Saturday night in December 39 years later when his tinkering paid off in an important discovery.

The discovery is complicated, but basically it involves using vulcanized rubber and a solid, inorganic oxidizing salt as bnding elements in a solid explosive compound that can be used, among other things, as a rocket propellant.

Long years of frustration followed.

The World War 11 was on, and Moore tried to interest the Navy in his explosive, according to court documents. The Navy wasn't interested. He tried to interest private companies and others with little luck. The years dragged on.

In 1948, when Moore was already an old man of 71, he entered into a contract with a company that manufactured a quantity of his "Moorite" explosive and coaxed military authorities into testing it.

No military sale resulted from this, the court documents show. Worse, according to Moore's attorney, the report on the testing was classified secret. Although it was distributed to dozens of private and government organizations and laboratories, officials refused Moore a copy until 1962.

The report noted some problems with the invention and recommended "further consideration" and testing for it.

It is not yet clear what the government did after this, but Moore, for his part, continued trying to interest private companies in his invention. In 1955, the United Mine Workers' John L. Lewis became interested in Moorite because its cases were "breathable" Moore filed for a patent.

The government clamped a secrecy order on the patent application, as is done in cases where military secrets may be involved, and the UMW's interest faded. A 9-year struggle followed, and Moore won his patent in 1964. He was 87 years old.

Seven years later, believing that the government had actually used his invention, but without telling him or paying him for it, Moore sued. After hearings this summer, U.S. Court of Claims Judge Joseph Colaianni ruled against the government's preliminary claims that Moore had legally "abandoned" his invention by waiting so many years to file a patient.

The more substantive hearing - on whether the government actually infringed on Moor's patent - remains to be held. Colaianni is said to want to schedule it as quickly as possible, perhaps in January, in view of Moore's age.

Moore's attorney, Joseph Magnone, said he has been allowed to study secret Navy, Army, Air Force and NASA material will be a key part of the trial. He declined to say more.

Through all these years, however, Moore's frustration over this particular invention, was only a part of a busy life.

He made a high income as a patent attorney for others, traveling frequently to Europe for his clients. Over the years, he patented more than 50 others inventions of his own, starting with a "milk jar closure or cap" in 1904 and including "interchangeable platen for typewriters," staple-affixing machine," "fish lure," "electrical sound-track recorder for moving picture printing machines," "metallic bird box or house," and "fruit rind removing machine."

He married his first wife in 1901. When she died in 1947, he married another woman who, he said, had been his mistress for 12 years. After she died, he married a 56-year-old woman in 1956 when he was 79 years old. When she became sick and thought she would die, he said, she engineered a divorce because "she didn't want me to have her real estate."

Despite all these marriages, the most important woman in Moore's mind remains his mother. He was the last child, and she hung onto him for years, he said. "I loved her more than I loved any of my wives."

Moore has no natural children, he said. But 10 years ago he encountered an inventor named Michael Rossman in a barbershop. The pair became friends, Moore went to live with Rossman and his wife, Barbara, in Silver Spring, and two years ago he adopted them as his children. Rossman has received publicity in connection with his attempt to perfect a crab-picking machine.

Another close friend is Charles Hamel, formerly an aide to Sen. Thomas Dodd and now an international management consultant. Hamel is helping Moore fight his legal battle.

Moore has recently had cataracts removed from his eyes and uses a hearing aid. Otherwise he seems fit. He has never smoked, although when younger he used to drink cocktails.

Longevity is in the family. "My father died when he was 93, my mother when she was 99," he said. "My brother Will was 96. My sister Rosalind was 98 (she was Dr. Rosalind M. Bain, a pioneer D. C. woman dentist. The only one who died young was Ben. He died in 1903 in Cuba with the army of occupation. He was a rough liver . . ."

Moore, formerly an avid reader, can't read any more. But he can quote Shakespeare and other poets at length, and frequently does.

His voice rose and he sat forward on the sofa in the Rossman's comfortable living room as he recited the last stanza of Longfellow's "A Psalm of Life."

Let us, then be up and doing, With a heart for any fate; Still achieving, still pursuing, Learn to labor and to wait.