THE BRIDGES OF MADISON COUNTY (1995) *** 1/2 Directed by Clint Eastwood. Produced by Clint Eastwood and Kathleen Kennedy. Written by Richard LaGravenese from the novel by Robert James Waller. Photography, Jack N. Green. Editing, Joel Cox. Production design, Jeannine Opewall. Music, Lennie NIehaus. Cast: Meryl Streep, Clint Eastwood, Annie Corley, Victor Slezak, Jim Haynie. A Warners release. 135 min. Rated PG-13.

The film describes the chance meeting between a man and a woman, who, although satisfactorily married, without premeditation fall in love and have a chaste affair that is predestined to come to an end. This is such movie perfection that it has become the measure of all "brief encounter" movies -- not that there are so many of them. Screen romances seem to go from happy endings to somber tragedies with little middle ground.

"The Bridges of Madison County" is remarkable not only as a movie but, most probably, as the Number Two brief encounter picture in celluloid history. Its best-selling book source -- known even to those who have not read it -- did not exactly shake literature to its foundations, but the screenplay adaptation is one of the very best jobs ever done of improving a novel.

As a reminder, the story is set in 1965 . Francesca Johnson (Merryl Streep, now 46) is an Italian war bride who, for 20 years, has lived in rural Iowa a normal, uneventful life. Her teenage children and her husband, all nice but unloquacious, are off for a few days to the Illinois State Fair. A chance meeting with Robert Kincaid (Clint Eastwood, now 65), a photographer on a National Geographic assignment to shoot covered bridges, transforms Francesca's life - and Robert's.

As scripted, the film, albeit without telegraphing its development, makes its progress and outcome unmistakably clear from the start. The main question is not whether or not Francesca will abandon her family and take off with the photographer, but whether the plot will opt for reality (sex) or for the conventions of the original "Brief Encounter" and those of 1960s rural Iowa (no sex). This is really a minor aspect. What grips the spectator is the rapid birth and growth of an unexpected yet so understandable passion, not only in the farm-wife who encounters her first glamorous man ever, but also in the peripatetic, fancy-free, attachment-less, wordly Robert.

There will be, no doubt, a great deal of surprise about Eastwood's romantic persona here, a surprise that comes from the Clintian icon as a myth whose significant other is a western six-shooter or a police Magnum gun. This is unjustified however when you think of the rich scale of characters that Eastwood has played and/or directed. (And this is my chance to plug once more his "White Hunter, Black Heart" of 1990, a gem that bombed at the box office).

It is interesting to note too that in the film, Eastwood's Robert is unencumbered by the machoism and grandiloquence of the novel. He does not try to pose as a soulful intellectual but brings instead to Robert the calm and sharpness that go with being an experienced, visually literate photographer. His acting has just the right tone of an aging but vigorous man who is surprised by his own reactions.

Meryl Streep, the accent lady, the chameleon actress and the woman of a thousand faces, reaches another acting peak. From her Italian accent --slight and exactly right for someone who has been speaking only English for two decades -- to her well-padded but warmly sexy figure, to the precise choice of dresses and housecoats, to her bare feet, she is the Italian girl who had been subdued by twenty years of Midwest farm-life. Her aquiline nose helps too.

Streep's effects are incredibly well calculated, so ably that you see them not as effects or mannerisms but as one hundred percent authenticity. She does things with voice, intonation, body language, looks, glances, little gestures and movements that should be analyzed minutely in advanced acting classes.

One example among dozens: When Robert tells her a funny story about an encounter with a gorilla, she laughs and laughs -- with a slight but clear trace of shrillness, something that brings out perfectly her many years of dull and colorless life. Miss Streep also brings out the complexity within an "ordinary" woman and she does so in an immensely appealing way.

"Bridges" uses a framing story (not in the book) which is clever, if marginally clunky. On a single viewing, the movie's weak points are few and of little weight. Among them is a little kitchen radio that broadcasts in amazingly hi-fi surround sound. Some scenes are held a mite too long. And one of them, a bath "a deux" with wine glasses and candles, is too much of a popular cliche of romance. But then there are dozens of privileged moments, not least among them the time when Francesca, speaking on the phone, touches Robert's shoulder for the first time.

To what extent "Bridges" and the performance by Streep will be remembered next year at Oscar time, I cannot tell. I cannot tell either what impact this October-November romance will have on the masses of viewers in their teens and twenties. But I am certain that for film connoisseurs and older audiences "Bridges" is a total winner.

I have not read anywhere that the makers of this movie studied "Brief Encounter", but I wouldn't be surprised if they had, as a detailed analysis of both movies would bring out influences, down to a score that often sounds like the Paganini-Rachmaninoff Variations. ("Brief Encounter" used gloriously and effectively Rachmaninoff's Second Piano Concerto throughout.) And there is something in common between the British film's Trevor Howard and Clint Eastwood: both men look serious, have no matinee idol looks, and possess flat voices. (Curiously, Celia Johnson was 37 and Trevor Howard 29 though he looked older).

Over and above its intrinsic merits (including splendid photography), the film is credible. Our times have made us --whether we realize it or not-- cynical,or at least blase and skeptical, about love affairs. When so many marriages end in divorce, when step-parents or single parents abound, when the media daily trumpet the great romances of celebrities... and then these are dissolved in weeks or months, it is very hard to take seriously affairs of the heart on the screen. But a short, mature affair without a tomorrow is quite believable and affecting. And the very impass on which "Bridges" is built is what gives it its power.