There was much banter about who would be the first to try out the new ambassador's scuba gear - with the President contributing heavily to the mirth - at what could become Atlanta's unofficial guesthouse in the turquoise Carribean.

Hamilton Jordan was among those said to be jockeying for a weekend at the residence of the new U.S. Ambassador to the Bahamas, Atlanta businessman and long-time Carter supported William B. Schwartz Jr., 55, along with the ambassador's friends, his children, friends of the children and friends of friends.

Vice President Mondale swore in the new ambassador, natty in a dark blue suit and red peanut club tie, in the Rossevelt Room of the White House yesterday afternoon. It was a warm, personal ceremony that observers said departed from the usual diplomatic neutrality at such affairs and included the President. He wandered into the room midway during Schwartz' acceptance and held forth with five minutes of humor and praise, joining 40 Atlanta friends and others who have come North to serve: Carter's congressional liaison Frank Moore, Adaman Gedald Rafshoon, special assistants Jordan Stu Eisenstadt and Jack Watson. Old home week, in effect.

Scuba diving with the Bahamian chief of state, joked the President, would be among Schwartz' first order of business and "May by one of the most, important diplomatic arrangements to be consummated."

"Bill had one great disappointment," Carter went on. "He would rather have gone to Norway or Iceland, but he was willing to make this sacrifice for oud country." Friends and family broke into laughter and applause.

Aside from accenting the President's sense of humor, the ceremony also underscored how important it can be to do business through someone who has a "personnal relationship" with the President of the United States. Carter said so himself.

It would give Americans and Bahamians "a bonus having an American ambassador who is close to the President," said Carter. "I've known Bill for a long time and he's known me well." Yet the appointment, he said, was not purely founded on friendship, but "one hundred per cent on merit."

Bahamain Ambassador to the U.S. Livington B. Johnson seemed extremely pleased. "It's not every day you attend a swearing-in with the President, the Vice President and so many others high up in the government in attendance," he said. "It was very intimate and highly unusual. All the other (swearings-in) I've been to were in the State Department by some protocol officer."

Several Atlantans however, appeared to carry around a bundle of emotions, mixed with highs and lows. On the way over, they had attended a goodbye party for Bert Lance in his office. "At least he's leaving with dignity," sald one Atlanta real estate magnate. "He can have any job in Georgia he wants."

After the swearing-in there was a reception in the Jefferson Room at the State Department, where stern-faced servants in tuxedos poured champagne and passed plates of watercress sandwiches and sugar-coated pastries. No one ate because it was too close to dinner time and the tid-bits looked so fattening.

Schwartz, who first met Carter during his 1970 governor's race, called the day "the high point of my life. When the President said all those nice things about me, I had to turn around and see who he was talking about."

Everyone padded up to Schwartz and told him how proud they were. Charlotte Garson, a tall Atlanta woman in a frilly chiffon who has spent enough time around the inner circles of power and high finance not to be awed - her family owns the Loveable Brassiere Co. of Atlanta - confessed she actually had cried during the ceremony.

But, she added, "You can have all this, darling. I don't want the responsibility of power. I'm getting too old, I'd rather do as Voltaire said, 'Cultivate my own garden.'"

"What you'll have here is a man who has been raised and educated all his life to become ruler of Great Britain talking with a guy who would like to be ruler of the U.S. some day," said a spokesman for the aspiring U.S. ruler, California Gov. Jerry Brown.

Brown is scheduled to have lunch with Prince Charles Oct. 29 in Sacramento, the last stop on the prince's 13-city tour of the United States. The spokesman said it will be very simple, "maybe, a bean sprout sandwich or something just as simple. I would like to see them go off by themselves together and just have really good talk."

The prince will arrive in the United States Oct. 18. His first stop is Chicago.

Nigerian head of state Olusegun Obasanjo, who will be in Washington next month and who President Carter will visit in his trip abroad in November, gave at least one young Nigerian a taste of the discipline he has committed himself to enforcing in Nigerian society.

Over the weekend Lt. Gen. Obasanjo walked unannounced into a government secondary school and caned a pupil for being shabbily dressed, according to the simi-official Daily Times newspaper. It said the Nigerian leader handled out three storkes of the cane to the 12th-grade pupil and also demanded an explanation for the school's poor performance in scholarstic tests.

Singer Jerry Lee Lewis has been indicted on drug charges by a Memphis grand jury. Lewis, 41, was arrested three months ago after police officers saw a car weaving along a highway near his home in Collierville, Tenn. He was indicted Friday on charges of driving while under the influence of drugs and possession of controlled substances.

Glaadys Knight and the Pips have been accused of violating a noise ordinance. The singing group performed at an outdoor Greek amphitheater in Griffith Park, Calif. over the weekend. Homeowners in the nearby Hollywood hills area complained the sound from the concert drifted from the amplifiers to more than 50 feet beyong the park property line.

Police responded to the complaints be issuing a misdemeanor charge against the theater corporation with a contract to operate the city-owned theater.

Another rock groups, named after the Windy City, is more appreciated in Chicago. In fact, the group "Chicago" even received the city's Medal of Merit last year from the late Mayor Richard J. Daley.

The eight members, six of whom hail from Chicago, decided to reciprocate the gesture and gave a benefit concert Saturday at Soldier Field for an estimated 30,000 to 35,000 persons. The benefit was for the Lincoln Park Zoological Society, and the money raised is to help enable the zoo is continue free children's admissions.

Amos 'n Andy, Liz Taylor, Richard Nixon, Gerald Ford, Lyndon Johnson and MIlton Shap won't be voting in South Philadelphia this November. Neither will Joseph J. Calciano, 36, who has been convicted of 160 counts of fraudulently signing the celebrities' and others' names on voting certificates during the 1976 primary.

Although Calciano's attorney claimed the forging was done in jest and in mockery of a polling place that has a history of such things. Philadelphia Judge J. Earl Simmons, Jr. did not find the actions funny. He sentenced the city recreation worker to three-to-six months in jail.

The judge dismissed another 630 counts for lack of evidence and added that the reason for sending Calciano to jail was the scope of his "joke."

"Certainly it looks like a carefully orchestrated plan to get the public to accept the fact that it is an ongoing relationship. Roddy is here to stay," remerked the London Sunday Mirror about the new, neat image of Roddy Liewellyn, 29, the constant escort of Princess Margaret.

The sister of Queen Elizabeth is legally separated from her husband, Lord Snowdon, and it is expected they will be divorced next year. Liwellyn, who is 18 years younger than Princess Margaret, has been seen more openly and frequently with the princess. he has abandoned his jeans, T-shirts, sneakers and gold earring and has a short, well-combed hair style, the newspaper said.

The new appearance has led The Sunday Mirror to comment that he now seems lie a suitable official boyfriend, "or dare one ponder; her prospective husband."

Actor Walter Pidgeon left St. john's Hospital in Santa Monica yesterday after a six-week stay for an operation to remove a blood cloth in the brain. Pidgeon celebrated his 79th birthday in his hospital bed over the weekend.

Deborah Ward.