ONLY A FEW authentic heroes were produced by the Watergate scandal, one of whom was a most unlikely candidate for the role. Four or five of Watergate's small band of knights were out of the heroic mold, without doubt. Archibald Cox, Sam Ervin, Elliot Richardson, surely; Leon Jaworski and Peter Rodino, most would agree. But John Sirica?

There are those who would have said that Judge John Sirica represents nearly everything that can go wrong with the federal judicial selection process. His nomination to the U.S. District Court for the District of Columbia in 1957 came as a reward for political service among Italian voters during the two Eisenhower campaigns, and it didn't hurt that he was a pal of Leonard Hall, chairman of the Republican National Committee. Sirica's other credentials included the absence of a full high school education, no undergraduate education whatever, mediocre law school grades (he had, however gone to an excellent place: Georgetown), and a law practice which could not be considered distinguished. Once on the bench he developed a reputation for being a careless and irritable trial judge whose main claim to local fame was the sometimes questionable wielding of his sentencing powers.

No wonder there was some groaning at the Bar, and elsewhere, when John Sirica, as his court's chief judge, assigned the Watergate break-in case to himself. A case of potentially monumental sensitivity and import involving Richard M. Nixon's administration was now to be presided over by a conservative Republican judge of apparently meager qualifications who had twice campaigned for the presidential ticket which had included Nixon.

Few observers anticipated that Sirica, like other judges before him, would eventually demonstrate that elitist standards are not certain and invariable predictors of admirable judicial service. Not many sensed immediately that John Sirica would prove to be the federal trial bench something of what Harry Truman had been to the office of the presidency: tough, tenacious, and-dare one put it this way?-patriotic. Sirica was the flawed but preeminent hero of Watergate Apparently the only person whose opinion is worth anything who will deny this is John Sirica.

We have previously had almost every perspective on Watergate, mostly reflecting the narrator's own intensely partisan involvement in the affair either as conspirator or prosecutor. We've had the books of Dean, Ehrlichman, Haldeman, Jaworski, Nixon, and Woodward and Bernstein, to name the ones I have read. Only the contributions of special prosecutor Jaworski and the two journalists seem untainted to any significant degree by the sort of interest which warps truth. That is why many people, appalled and puzzled by Watergate, have wondered whether Sirica-who, more than any other, stood above the contending factions-would ever add his perspective to those already recorded. That is why many will be glad that the Watergate judge has now put his own thoughts and recollections about this sordid episode in our history.

Watergate, as everyone knows, was a real-life morality play, with Nixon and his top aides the New Amoralists. Nixon, foul-mouthed and cynical, conniving and corrupting, lying and blaming, will not be the man mentioned by proud parents telling their children that they could grow up to be president.His chorus of cohorts will be remembered as Haratio Algers and Tom Swifts gone rotten. Watergate was a tale of unrelenting malevolence, which could have been made worse only if its disposition had been assigned to a weak or venal judge.

As it happened, it fell to the lot of a man of old-fashioned virtues-and faults-to preside at the unmasking of Nixon and his baleful crew. Predictably, the Watergate litigations provide the chronology on which Sirica pins his impressions and conclusions and some startling behind-the-scenes vignettes. The result is the most credible and, in many ways, the strongest and most revealing book about the Watergate affair.

Judge Sirica opens with a brief autobiographical sketch. It is what we too comfortably call The American Story: immigrant parents; struggling, losing father; the eventual upward arc of the son's carrer (after a short detour into professional boxing). It is an unassuming even humble account, yet one which glows with the sort of pride. which, one recalls, was never too embarrassing to be expressed by such different men as Earl Warren and Felix Frankfurter.

Then, writing in a clear style not too heavily larded with legal jargon, the judge gives a sequential description of those Watergate proceeding which came into his courtroom. Basically, these were the break-in prosecution (undramatic except for Sirica's intrusive efforts to find out who paid the perpetrators-and until, after the trial's conclusion, James McCord presented to the judge a letter which was the first faint signal of Richard Nixon's fall); then the battle for the tapes (interrupted by the Saturday-Night Massacre); and, finally, the trial of all the conspirators except the pardoned president.

It is the tapes dispute which provides most of the high drama in the Watergate story. Sirica offers a fascinating account, made all the more so by its revelation of a judge's thought processes in the matter which, with dizzying rapidity, took on dimensions of historic magnitude. The notion that judges must from time to time undergo days and nights of mental torment is amply attested by these chapters. There were easy paths he could have taken; Sirica chose all the hard ones and very nearly paid with a burst heart.

Along the way he formed opinions, lots of them, most of which he has kept to himself until now. His book leaves little room for speculation about Sirica's assessment of the prominent lawyers who trooped before him, although occasionally one must weight his words carefully. (Who comes off better here: "Special Prosecutor Cox was, of course, one of the country's preeminent consitutional scholars.

The President had obtained the services of Charles Alan Wright, from the University of Texas Law School, an outstanding constitutional lawyer"). The lesser conspirators are all more interesting than the humorless White House crowd. One would search long and hard for a character more deeply weird than Gordon Liddy, whose daffy schemes held all too much appeal for a paranoid administration. And for what little comic relief there was, it's hard to beat Tony Ulasewicz, the bagman who had to make so many drops of Watergate hush money in D.C. phone booths that he took to wearing a busman's coin-changer on his belt.

There were sad moments, too. For all his hard exterior, Sirica has a heart which can comprehend the tragedy of so many smashed lives. He can think back, shaking his head, on the irony that John Dean, as a promising young law school graduate, had apparently hoped to serve as Sirica's law clerk. And he comes closer than anyone has to making John Mitchell seem a sympathetic character.

Sirica minces no words about the principal conspirators, among whom he unmistakably counts Nixon himself. "Their lust for power, their arrogance, their raw disregard of the law, of fairness, and of the very constitutional processes that they had sworn to enforce and protect, led them to break the law in order to keep themselves in office." Sirica is explicit. The tapes "put Nixon at the head of the conspiracy to obstruct justice." In Sirica's view, the man who had primly asserted, "I am not a crook" was that and worse."The truth is that Richard Nixon left office because he was on the verge of impeachment. He was on the verge of impeachment. He was on the verge of impeachment beacuse there was overwhelmingly convincing evidence, mostly from the grand jury sitting in the Watergate case, that he had committed criminal acts."

So strongly does Sirica feel this and so strongly does he feel that the public should have known this as a certainty, that he declares, "Nixon should have been indicted after he left office." More than that, "If he had been convicted by my court, I would have sent him to jail." For those who feared that John Sirica would permit his own political roots to exert a pull on the judicial process, there are these words: "I hope no political party will ever stoop so low as to embrace the like of Richard Nixon again."

How does John Sirica judge his own conduct? "I think I did my job as best I could. I think I did my duty as a citizen and as someone fortunate enough to hold a position of public responsibility in our system of government."

So say we all. CAPTION: Illustration 1, no caption, by Roxie Munro; Illustration 2, no caption, by Roxie Munro