FASCINATION WITH TIME : AUTHOR USES SCHOLARSHIP TO FASHION FICTION.

Byline: Francis X. Clines The New York Times

Thomas Mallon is busy arranging a fresh love affair for one of the great philanderers of Washington political life, a big, charming man with that power politician's grin who crests scandal with the self-confidence of every victor who has ever reigned here.

``The historical figure that I'm libeling in this novel, whose ghost I'll fear meeting up with, is the now completely forgotten figure of Roscoe Conkling,'' said the 45-year-old writer, who diligently uses scholarship on this city the way he might apply a clam rake to rich muck, then fashions the succulent gatherings into fiction.

``Conkling was the senator from New York who was this great handsome man and a real brute,'' said Mallon, fresh from another morning at the National Archives deep-dredging the recorded Washington stuff of a century ago. ``He was THE power in the Republican Senate and really the boss of New York. He owned Chester Arthur. He controlled the Custom House in New York. He was a great womanizer whose most famous affair was with Kate Chase Sprague, Salmon P. Chase's daughter who -''

But wait. There is so much that is refreshing in Mallon's backward-accounting ability - a reminder that there is nothing new, absolutely nothing, in the current sensations of this city - that he himself deserves a moment of pause in the here and now.

With his new novel, ``Dewey Defeats Truman'' (Pantheon; $24), which is just out, Mallon is already elsewhere than the 1940s setting where his readers are luxuriating in that work, a novel about a small-town love triangle in Owosso, Mich., Thomas E. Dewey's birthplace.

There, the writer has his resident characters, so certain of favorite-son triumph, awake from their ``collective dream'' the morning after President Harry S. Truman's upset defeat of Dewey.

``I saw the town sort of shimmering on the edge of romance,'' said Mallon, who came upon this teasing notion in writing a nonfiction magazine article about small-town America. ``I was enchanted by the place. There must have been something both comic and poignant the morning after, I thought.''

Overlooked tales

As a writer, Mallon darts across time. He is best known for his 1994 novel ``Henry and Clara,'' a work set in Lincoln's Washington that impressed critics with its mix of careful research and fictional liberty. In it, he told for the first time the full tragedy of the handsome young couple invited by the Lincolns to that Ford's Theater box on the infamous night of assassination. It is an overlooked tale, sad beyond Lincoln, of love withering to madness and murder.

``I'll probably never find another story like that, but it was so doom-laden,'' the novelist said, in explaining how welcome it was afterward to turn to the dreamy innocence of Dewey's Owosso.

If modern spin doctors could have worked for Dewey, he thinks, they would have made Owosso into the sort of Russell, Kan., tale that the Bob Dole campaign tried to spin all the way to the White House.

``Every president makes use of his own story,'' said Mallon, finding ``the man from Hope'' off the mark. ``The smooth operator side of Clinton would be better told in terms of Hot Springs.''

It is the ``fullness of history, the amplitude of it,'' that convinces Mallon he will never suffer writer's block. ``Anybody who thinks the federal government can't do anything right should go to the National Archives. You can spend a morning there stumbling around and still come up with half a dozen possible novels that you could get up and running very quickly.''

When he bothers to spy upon the present, Mallon's eye for detail stays keen. ``Did you watch Dick Morris on TV the other night?'' he asked, referring to the former Clinton political tactician who fell lecherously from grace and is now hawking his tell-all White House memoir.

``At one point, they showed him at his desk and you could glimpse behind him two framed pictures, both of Time magazine covers - one of him with the president, and one after his fall, with his wife! I couldn't believe it. What sort of a guy chooses that display?''

Mallon has a pretty good answer for such a question but prefers to offer it in some other time frame than the present.

Former English teacher

``History is so much gaudier than one's own life,'' said the writer, who used his Harvard Ph.D. in English to teach at Vassar for 12 years, then finally took a chance on writing as a living. ``My life is pretty thin gruel for fiction,'' he said, speaking as both novelist and book columnist for Gentleman's Quarterly. ``So many novelists write about things that are right under their noses that we have all these novels about New York media life and college life.''

The way Mallon works, it's not that his ego is absolutely denied; rather, it's ``refracted,'' to use one of his favorite words, in various imagined ways in time elsewhere. A busy nonfiction writer, too, he specializes in science pieces on astronomy and cosmology, time and space.

``Time is the great mystery,'' he said. ``Time, more than anything else. More than any emotion. More than love. Time is the essential human mystery.''

Small wonder that he is lately busying himself here in the 1870s, rummaging in a kind of researcher's nirvana through troves of archival ledgers and letters for his Conkling-era novel.

As he is plotting it, the new book will arch beyond power-lusting to the nation's early fascination with astronomy in a highly anxious, uncertain time, and to the actual discovery of the moons of Mars (named Anxiety and Fear) from the Government Naval Observatory built then in Foggy Bottom as one of the wonders of the city.

Among the novel's ingredients collected thus far by Mallon in reading the records of that day: that ordinary citizens sampled the stars at night at the observatory; that three successive observatory superintendents developed malaria from the mysterious ``miasma'' (actually from the mosquitoes of Foggy Bottom); that young female clerks called ``computers'' aided the observatory scientists; that a woman on Sixth Street named Madame Costello advertised ``planet readings'' that were popular as a seer device in the populace's parallel craving for astrology.

Mallon apologized for these early shards of plot. ``Cynthia is my new heroine,'' he nevertheless continued, trying to show how one writer's work obsession proceeds. ``She is in love with this tragic malarial astronomer at the observatory. But she's also being pursued by the terrible but magnetic Conkling. She consults Madame Costello about her love life.''

The novelist smiled at the past from the present. ``So she's involved with the planets every which way,'' he said, noting that the novel was tentatively titled ``Two Moons.''

``This novel is about time,'' Mallon said, returning to his preferred dimension. ``The notions of the speed of light and the vast distances of space were just being established in that period. Visionary scientists were beginning to glimpse the way time and space fold over on each other. And to me, that's the heart of it.''

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2 Photos

Photo: (1) Thomas Mallon

Now busy in the 1870s

(2) (Book cover of DEWEY Defeats TRUMAN)