UNDER THE tutelage of Rep. Barney Frank (D-Mass.), the House of Reresentatives had a bright interlude of sanity. It didn't last, of course. The total duration of the brief excursion into reality was two hours and five minutes, and when it was over, the MX missiles that nobody except Caspar Weinberger really thinks make America a safer place were back in the defense appropriations bill.

Frank didn't tell anyone he was going to introduce a "perfectly straightforward amendment" to cut .7 billion for 12 new MXs, four of which can never be used except as spares. He just got up and presented it.

The Republican and Democratic hawks were taken by surprise. The vote was 211-208 for excising the missiles.

It showed that when left to their own devices, without pressure from the White House and their leaders, even 37 Republicans rise up against the derelict weapon that lurches through Congress periodically with its hand out.

"They didn't have a chance to ask Mommy's permission," said one observer of the astounding outcome. "They had to wing it, and they did the right thing."

Frank cast the choice in terms of particular allure for people who are about to embrace the Gramm-Rudman amendment, that curious remedy for deficit spending which mandates presidential budget-cutting when Congress can't do it.

Voting for his amendment, he told the House, "just plain flat out cuts the deficit."

It doesn't take the world's most tightly wrapped intellects to understand that building 12 new missiles -- only four of which under the law capping the number at 50, can be deployed -- is an exercise in conspicuous Pentagon consumption.

House Speaker Tip O'Neill, having been apprised of the constructive mischief afoot, hurried on to the floor to take a hand. He welcomed a chance to to embarrass the Republicans and to show Ronald Reagan that the "Peacekeeper", as the President likes to call the turkey, has few real friends. O'Neill reproached Frank for not giving proper notice, but absolved him by saying "You did the right thing," and waded in to massage a few backs and twist a few arms for the cause.

While he was making the argument for common sense and good politics, his one-time protege, John Murtha of Pennsylvania was working the floor with an urgent appeal to rebellious members "not to cut the president's legs off at Geneva."

By this time, however, the White House was fully mobilized, and a rescue operation for the MX was under way. The telephones began to ring -- the message: The President needs the Peacekeeper at the summit.

Under its rules, the House having completed action on a bill, rose and was transformed from the "The Committeee of the Whole" back into being the House of Representatives to vote on final passage.

Frank stood at the door as members filed in for the final roll-call. He handed out flyers headed "Attention, Deficit- Reducers, Get a head start on meeting your own personal Gramm-Rudman target without injuring national defense."

"Several people who were with me switched," he said the next day, still savoring his flitting victory, "and some of them disappeared."

The vote was 214-210, "a damn close-run thing," as the Duke of Wellington said of Waterloo. The White House was on notice about angst over "peace through strength."

Frank has proved his point, and he intends to make it over and over again with the opposition. He is probably the sharpest member of the House, an ultra-vocal liberal and expert needler, who pricks the pompous with much-quoted aphorisms. He knows the rules of the House and the rules of the game. As befits a former member of the Massachusetts General Court, the Bay State's name for its legislature, he has little reverence for the established order, and no prejudice against having fun in politics.

Right now he is compiling a list of Republicans who voted against his MX cut to hold up when they vote also for the dairy subsidy bill. He will remind them that they fought a modest $355 million measure to build houses for the poor and homeless and then gave $1.7 billion to build 12 missiles nobody needs.

He is not troubled by complaints about his "sneak attack" on the MX. When he was fat and sloppy -- he has since become a svelte fashion plate -- his campaign slogan was "Neatness isn't everything." He still doesn't think it's everything in setting a trap for people who say they want to reduce the deficit and kick away chances to do it.