A S ANY ONOMASTICIAN WILL TELL

you, Washington is the initial capital of the nation, if not the world. Onomasticians -- folks who study names -- find this town's names rather amusing, a symbol of the formality and insecurity of power.

From Capitol Hill to the Pentagon, on bylines and letterheads, "there is a kind of tradition in Washington that people have a middle initial, even though hardly anyone uses middle names anymore," says Leonard Ashley, president of the American Name Society and an English professor at Brooklyn College. "The genesis is the Army and the bureaucracy. If you're in the military without a middle initial, you run the danger of being called Joe NMI Smith -- No Middle Initial."

"It's a rather pompous way of presenting a name," says Fred Tarpley, an English professor and name expert at East Texas State University. "Especially the first initial. People defend it by saying they didn't like their first name. But of course instead of J. Alfred Prufrock, they could say Al Prufrock and nobody would know better."

Sometimes the initial can be conferred on the subject without his knowing it. Sen. Bob Graham, the first-year Democrat from Florida, has been just plain Bob most of his adult life. That's how he appears on his stationery and even on the ballots back home. But after arriving in Washington this year, he's appeared in the press now and then as D. Robert Graham. (For the record, his press secretary, Ken Klein, is not sure how it started.)

Defenders of the initial initial say the letter can be assertive, as in J. Edgar Hoover or G. Gordon Liddy. From the financial world, think of the power pill an extra letter provides H. Ross Perot and T. Boone Pickens.

Middle initial mavens speak of the stylishness of their additions; after all, what would Edward G. Robinson have been without his G? If you tried knocking the L. out of John L. Sullivan, he'd have knocked the L. out of you.

The experts scoff. They say the excess initial is a crutch that often falls away as the person becomes more secure. "Ronald Reagan doesn't need an initial," Ashley says. "You're much more important without it."

Ashley also points out that William F. Buckley Jr. "has reached a stage where he could be William Buckley. He doesn't need the appendages anymore." But Buckley's craft makes such a change unlikely. Writers who have established any degree of byline fame are often stuck with their monikers.

Initial trend watchers have also detected a new popularity of middle letters among professional women, especially lawyers. But the practice is still largely an American phenomenon, Ashley says. In fact, in some English novels the plot hinges on the idea that a character is secretly American. The clue: No Englishman would use a middle initial. ::