Albino Luciani, the 65-year-old patriarch of Venice and described as a moderate conservative, was elected pope yesterday on the first day of balloting by his fellow cardinals. His selection and the speed with which it was accomplished were both unexpected.

The new pope, who was cheered by hundreds of thousands in St. Peter's Square when he made his first public appearance after his election, will reign as the spiritual leader of the world's 600 million Roman Catholics under the name of John Paul I.

Theologians regard Luciani's choice of name as significant. They see it as a declaration of intention to continue the work of his two predecessors, John XXIII and Paul VI.

Several cardinals here had said they would seek a pontiff who would insure continuity, a suggestion that the faithful have had to cope with too much change in recent years. This quality may have counted heavily in Luciani's surprisingly early choice, apparently on the fourth ballot.

In the realm of temporal politics, John Paul I is not likely to encourage the so-called historic compromise that gives Italy's Communist Party a growing voice in government.

He has said that Catholics in Italy must vote for a Catholic party, meaning the Christian Democrats. In the national election two years ago, Luciani was a leader among bishops who strongly urged a Christian Democratic vote.

But what a man does before he assumes the papacy is an uncertain guide to his behavior when he holds the keys to the kingdom. John surprised the world with his sensitive concern for the oppressed and Paul with his outstretched hand to other faiths.

The election and attendant ceremony yesterday demonstrated that the Catholic church has lost none of its capacity for drama. About a dozen cardinals were most frequently mentioned as likely candidates, and it was thought it would take several days of voting by the 111 who entered the conclave before any got the needed 75 votes, two-thirds plus one.

Luciani was in the group and he was chosen on the first day of voting. Two ballots were held this morning, but to the disappointment of the thousands assembled under a broiling sun in St. Peter's Square, black smoke billowed from the Sistine Chapel stack to signal that no agreement had been reached.

As the sun set behind the great dome of St. Peter's, however, just before 6:30, a puff of white smoke appeared. There were cries of "Bravo, bravo" from the crowd and many clapped their hands in delight.

[WORDS ILLEGIBLE] dismay of most, the stack began sending out what looked like gray smoke. "Nera, nera" --black, black -- the crowd chanted in disappointment.

Evidently, the chemical sticks burned to ensure an unambigous signal were less than a triumph for Italian industry. The stack was soon puffing vigorously again, shooting out plumes of unmistakeable white.

"Bianca, bianca" -- white, white --relieved women cried. A pope had indeed been chosen.

Some skeptics were unconvinced and the suspense remained until the great white drapes parted and the glass doors leading to the central balcony on St. Peter's facade opened. The senior cardinal, Pericle Felici, stepped out on the balcony and announced in Latin, Habemus papam --"We have a pope."

By then, the crowd had swollen to several hundred thousand, filling the great square embraced by Bernini's huge double colonnade. They roared with pleasure and listened closely for the name.

Then the rest of the cardinals who took part in the conclave, 110 in a blaze of scarlet, filled the three balconies on either side of the central podium. But all eyes strained to see the platform in the center.

First a cross appeared above the balustrade. Then, in a white cassock surmounted by a purple cape, the new pope appeared. He raised his hands, as if to bless and embrace everyone. The throngs roared with delight and waved their handkerchiefs at him.

He looked to be a large, heavy man, moved by the joy and solemnity of the moment. He recited the traditional blessing, "urbi et orbi," asking God to bless the city of Rome and the world. John Paul I chanted the prayer in a high, occasionally quavering voice. The people below responded with "amen" and some knelt on the paving stones to cross themselves.

But when the Latin prayer ended, the new pope's evident delight was displayed. He repeatedly raised his hands in blessing and greeting, smiling broadly. Then, in the fading evening light, he withdrew from the balcony. The watching Romans, nuns, tourists, priests and journalists hurried away from the great square.

Luciani is a man whose origins are deeply rooted among the Italian people. His father was a socialist, a migrant worker in Switzerland and glassworker in one of those remarkable factories on the island of Murano, near Venice.

Luciani was born on Oct. 17, 1912, at Forno Canale, a village in Italy's northeast corner. He was ordained as a priest in 1935 and studied theology at several Italian church institutions.

Regarded as something of an intellectual, he has taught at the pontifical Gregorian University in Rome and at the seminary of Belluno.

For the past 20 years, he has filled a pastoral role, another point that must have recommended him, even to cardinals who have served most of their lives in the Curia or church bureaucracy. In 1958, he became bishop of Vittoro, Veneto, then archbishop and finally patriarch or cardinal in Venice.

At the Second Vatican Council, he was identified neither with progressives or conservatives. So it is not known whether he favors or opposes sharing power with bishops, modernizing the liturgy and enlarging the ecumenical links with other faiths.

Those familiar with Luciani, however, point out that he strongly favors communication, both with parishoners and the hierarchy. Thus, he is put down on the side of those who favor making the liturgy understandable, rendering it in vernacular tongues.

He has written several books including a collection of open letters to historical figures. Luciani is well-read and admires the work of Mark Twain among other American writers.

"I have to communicate," he once joked. "I preach in St. Mark's [the Byzantine marvel in Venice], a place filled with tourists where few people listen to me."

His willingness at least to engage in a dialogue with liberal Dutch and German bishops whose views he does not share may have helped him in the vote yesterday.

Luciani is essentially a traditionalist. He has issued strong statements against divorce and abortion.

As a bishop and cardinal, he opposed the controversial movement that drew priests into factories, the worker-priests: he is against women in the priesthood and he sternly opposed an Italian movement of priests who dissented from the divorce doctrine and tried to spread their views among grassroots parishoners.

Under Paul, the church launched a policy of accommodation with Eastern Europe.Paul himself as pope and in his earlier career as a vatican diplomat, visited Eastern European countries. But John Paul has never served outside of Italy and his views on foreign affairs are a complete blank.

The cardinals are sworn to secrecy so the world may never know with certainty why they chose Luciani. But his election as pontiff appears to make nonsense of the view that the prelates were ready to choose a non-Italian. John Paul, who now ascends to the papal throne, continues a line of Italian popes that stretches back 455 years.