It was one of those rare days in the Senate when the floor was crowded and no gavel rapped the demonstrating galleries back to order.

For five emotional minutes the chamber resounded with applause for Sen. Hubert H. Humphrey (D-Minn.), who stood at his desk for the first time since learning he has inoperable cancer.

Though his voice was weak, he managed again to out-talk all his colleagues combined. They got up, one after another, to pay their tributes to the Democratic Party's Happy - though ailing - Warrior.

"I got wound up," Humphrey conceded. "I didn't intend to be that long - but that's the story of my life."

Humphrey looked up into the galleries and blew kisses to his wife, Muriel, who waved back and struggled with her tears while others in the galleries swallowed hard.

Though his body was wasted by the ordeal of sickness, Humphrey spoke of the politics of joy and love and faith. He also spoke with self-deprecating humor.

His doctors, he confided, had approved his return to the chamber, his home - "but because I am a frugal man I waited until I could get a free ride." He referred to his jet hitchhike with President Carter from Minnesota to Washington on Sunday.

The laughter died down and Humphrey went on: ". . . for at least 20 years I've been trying to get on Air Force One." In those 20 years he sought the presidency three times and was rejected twice as his party's nominee.

He listened as Robert C. Byrd (D-W. Va.), who has the majority leader post Humphrey also coveted, called him "a great political leader who combined the best of mind and soul. He has indeed believed his heart."

And Wendell R. Anderson, the junior senator from Minnesota, quieted the room with, "to those who say there are no heroes left in the world - to them, I say, they have never known Hubert Humphrey."

When Humphrey entered the Senate at 2 p.m., the applause welled up and he moved around the floor like a campaigner. All that was missing was "Happy Days Are Here Again."

The applause swelled as he hugged many senators - Russell B. Long of Louisiana, Edward M. Kennedy of Massachusetts, Anderson - then bounded up the steps to where his "special friend," Vice President Mondale, presided, for another hug. Then he turned and shook the hand of every Senate page standing by.

Earlier in the day, Humphrey, who calls himself "the old professional policy-maker," said he had returned to be Carter's emissary on the Hill, an oft-alien world these days for the President.

That Carter should need the one man he ridiculed in campaign rhetoric as too old and a has-been, was forgotten in the ananimity of the spirit of the chamber.

Humphrey spoke of Carter only in supportive terms.

"The energy question, tax reform - there's an awful lot on the table. For that the President is criticized for trying too much, too soon, but a President has to lay out the program. In a democrary you don't move rapidly. Congress will have to feel its way," he said. "I want to help, doing the little errands that sometimes add up to small achievements."

He said he is "revved up" to "push hard for the basic principles of the Humphrey-Hawkins" employment bill, and predicted the President would get 65 per cent of what he is seeking in his energy package.

Humphrey, who has learned there are no miracle cures - "Listen, if there was any miracle cure. I'd have it by now" - said. "I told the President the greatest contribution he could make is to give people a sense of confidence - to give them hope and to have patience to solve their problems."

It was pure unabashed Humphrey, corn and all, when he said, "Gosh, this is a great country."

But more than that, it was a class act.