VATICAN CITY - One papal election held during a sizzling Roman summer had cardinals collapsing of dehydration and heart attacks. The top candidate eventually died, and the pope who emerged from a sweaty inferno worthy of Dante survived only 2½ weeks.

Another vote dragged on for more than three years. It might have gone longer had exasperated citizens not torn the roof off the cardinals' meeting hall and put them on a bread and water diet.

Shrouded in secrecy and steeped in centuries of tradition, the ancient practice of appointing a successor to St. Peter is serious business - but there's always the chance that things will get out of hand.

The Rev. Thomas Reese, editor of the Catholic weekly magazine America, likens the process to a restaurant that wants to serve customers a gourmet meal "but doesn't want them to stick their noses in the kitchen, lest they lose their appetites."

The 115 crimson-robed cardinals sequestering themselves inside the Sistine Chapel on Monday will be voting in a cool April instead of a hellish August. They'll also be enjoying greater creature comforts in the Vatican's new, $20 million Domus Sanctae Marthae residence than their predecessors did in the musty, cramped quarters of the Apostolic Palace.

The term "conclave" comes from the Latin for "with a key," reflecting the tradition of locking cardinals into a room until the job was done. John Paul's constitution for next week's conclave makes no mention of a key; it says merely that the chapel doors are to be closed and two Swiss Guards posted at every entrance.

Historically, the chances of something unusual happening increased as an election wore on. In medieval days, electors took their time picking popes, who enjoyed sweeping political powers. That's changed with the papacy: No conclave in the past century has exceeded five days.

Yet even in 1978, when two papal elections were held in rapid succession, the first vote was tinged with chaos.

The cardinals who elected John Paul I after casting four ballots over two days met in August, a month so oppressively hot that Rome typically empties as residents flee to cooler corners of Italy.

"We were dying of heat, asphyxiation seemed to be getting the upper hand, and I noticed that some cardinals were on the verge of collapse," Cardinal Giuseppe Siri, a perennial candidate for the papacy who died in 1989, once recalled in an interview with the newspaper La Stampa.

"Then I rebelled, and with the authority of a member of the supervising committee, I said: 'I order you to open the windows,'" Siri said. "Some responded: 'Eminence, it is not permitted to open the windows,'" because the faithful packing St. Peter's Square would be able to hear the cardinals' applause when the new pope was elected.

"I responded, 'What if they hear?' They opened the windows. Color began to return to the faces of the moribund," he said.

The concept of the modern conclave dates to 1274, when Gregory X decided cardinals would eat, sleep and vote in the same locked chamber. It's not difficult to understand why - the conclave in the town of Viterbo north of Rome that elected him pope began in 1268 and lasted more than three years.

"Toward the end, the people of Viterbo became so impatient that they tore the roof off the building in which the cardinals were lodged and put them on a diet of bread and water," Vatican expert John Allen Jr. writes in his book "Conclave."

Gregory was so worried about a repeat, he decreed that cardinals would get just one daily plate of food if a conclave stretched beyond three days, and be served only bread, water and wine if the deadlock exceeded eight days.