I found this fascinating, especially the silver hammer part.Every pope has the equivalent of a chief of staff, called the camerlengo. When a pope dies, the camerlengo must first certify that he is indeed dead. The ritual tradition is to strike him on the forehead with a silver hammer, calling his baptismal name three times. An alternative is to place a cloth over his mouth. If he does not respond, the camerlengo declares him dead, authorizes a death certificate and then seals the papal living and working apartments.
Later, the silver hammer will be used to scratch and break the papal ring and seal, so no documents can be forged in his name.
All cardinals will hasten to Rome to undertake the administration of the interregnum, the period between popes. The only governing they do is attending to administrative matters, overseeing funeral arrangements for the deceased pope and electing his successor.
In times past, outsiders pressured the cardinals to choose a pope to suit one faction or another. Wars were even fought between different blocs, delaying the selection of a pope for years in some cases. Three years after the death of Pope Clement IV in 1268, the cardinals still had not chosen a successor. Civil officials grew tired of waiting and locked the cardinals in their meeting place, tearing the roof off the building to expose the cardinals to the elements! Not surprisingly, they chose a new pope almost immediately!
That was Pope Gregory, who established a rule in 1274 that cardinals thenceforth were to be locked in with a key to avoid outside influence. The name of the process is a conclave, from the Latin com and clavis for, "with a key."
Today's conclave is very similar to what Gregory established. It is held in extreme secrecy in the Sistine Chapel in Rome. Before the meetings begin, the chapel is swept several times for electronic eavesdropping devices—something the church did not have to worry about in the 13th century. When assured of privacy, the cardinals are locked into the chapel and the doors are sealed inside and out with keys and ribbons. Every participant takes a vow of complete secrecy.
The balloting
The cardinals select three of their number to fill the role of scrutineers for every ballot. Everyone receives a piece of paper with Eligo in Summum Pontificem (Latin for "I select as Supreme Pontiff") printed on it. He writes his choice in disguised handwriting and folds the ballot over twice. Each then walks with his ballot, holding it high in the air, to where the scrutineers are seated. He places it on a plate and then tips the plate into a chalice, so all can see what he is doing.
After each vote, the scrutineers count the folded ballots to make sure they match the number of cardinals. (Only cardinals under the age of 80 at the time the pope dies are eligible to vote.) If the numbers don't match, the ballots are burned and not counted.
If they match, the first scrutineer takes them one by one and marks down the name. The second scrutineer does the same, creating a duplicate record. The third scrutineer pierces the "Eligo" on the counted ballot with a needle and thread, adding all ballots to a long string to ensure that they aren't accidentally counted more than once.
A two-thirds majority is necessary to elect a pope. If the vote is unsuccessful, all ballots and the string are burned in a stove with some chemical pellets that produce black smoke. The black smoke puffing from the chimney tells the world that there is no pope yet.
A second ballot is taken immediately. A third is taken in the afternoon or perhaps the next day. John Paul established a rule that allows the cardinals to choose a pope by simple majority if they haven't agreed upon one after 12 or 13 days.
When someone is chosen, he is approached and asked in Latin if he accepts. If he answers yes, he is asked by what name he wishes to be called. That follows a custom begun in 533 when a cardinal named Mercury was chosen as pope. The church did not think it appropriate for their leader to have the name of a pagan deity, so Mercury changed his name to honor a previous pope. Modern popes all do the same.
The successful ballot is burned with pellets that emit a white smoke, indicating that the church has a new leader. He is fitted with papal robes (several sizes are on hand) and immediately introduced to the waiting crowd in St. Peter's square.
http://www.ucg.org/wnp/wnp0409/manpope.htm