A caption in The Post yesterday stated incorrectly Alexander Hamilton and Aaron Burr took place in 1800. The dispute stemmed largely from the 1800 presidential election, but the duel did not occur until July 11, 1804.

For those who are still trying to keep track of all the unexpected happenings during this unpredictable election year; here's a new unlikely development: the 12th Amendment has emerged as a major topic of speculation within Washington's political community.

Amendment XII, a paragraph of elegant legalese that was added to the Constitution in 1804 in the wake of the duel between Aaron Burr and Alexander Hamilton, lays the ground rules for picking a president if no candidate wins a majority of the electral college vote in the general election. cWashington political buffs have suddenly grown interested in those rules because the presence of a viable independent candidate, John B. Anderson, makes it possible that the popular voting Nov. 4 could leave nobody with the required electoral majority.

Given the makeup of the electoral college, it takes only a small speculative leap to hypothesize a scenario in which Anderson and the likely major-party nominees, Jimmy Carter and Ronald Reagan, split victories in the 50 states in such a way that none has claim to an electoral majority.

If Anderson, for example, were to eke out popular vote plurality in one big state, while Carter and Reagan split the others about evenly, the nation could wake up the morning after the election without knowing who the next president would be.

That is the way things were supposed to work in the first place. When the authors of the Constitution settled on the electoral college compromise in 1787, it is clear that they thought the popular vote should be a means only to elect presidential electors, who would meet subsequently to make an independent choice of the president.

The electoral college was established, according to the Federalist Papers, because the founding fathers felt "a small number of persons, selected by their fellow-citizens from the general mass, will be most likely to possess the information and discernment requisite" for choosing the president.

Things worked fine under the original scheme for the first three elections. But then, in the 1800 contest, the electoral college vote ended in a tie between Burr and Thomas jefferson. A bitter political battle ensued, resultng in the election of Jefferson and the infamous duel in which Burr killed Hamilton. When the smoke cleared, Congress wrote the 12th Amendment, setting up the system that has selected presidents ever since.

The amendment preserves the electoral concept of the original Constitution:

the popular vote for president chooses not the president, but rather "electors" from each state.

Each state is entitled to as many "electors" as it has representatives in the House and Senate; in addition, the District of Columbia chooses three electors. That makes a total of 538 votes in the electoral college. A candidate needs a bare majority, or 270 votes, to win the presidency.

For the most part, the 538 electors chosen every four years for the most august job in American politics are nonentities.

Under the Constitution, each state can set its own means for choosing electors, and most states leave the choice up to the political parties. Each party designates a "slate" of electors before the presidential election; if the Democratic candidate carries the state, the Democratic electors are automatically elected.

Most voters never even know the names of the electors, although the electors sometimes take steps to change that. In 1976, when the Maryland Democratic Party gave Rep. Gladys Noon Spellman one of the honorary slots, Spellman issued a press release and then revealed her good fortune at a news conference. Only later did she learn that, as a member of Congress, she was constitutionally ineligible to serve.

On the first Monday after the second Wednesday of December in each election year, the electors in each state meet at each state capitol to cast the votes that formally choose the president. The electoral votes are then forwarded to Washington, where they are publicly counted before a joint session of Congress and the winner is officially determined.

The whole system works without a hitch as long as there is a clear winner of a popular vote majority and as long as the electoral college vote duplicates the popular vote total in each state.

But this year, if there is no majority winner, things could get complicated.

For one thing, there is no federal law binding the presidential electors to vote in accordance with the popular vote in their states. A minority of the states impose such legal restrictions.

Thus, the electors can vote for anybody -- even a candidate who appeared on no ballot anywhere. And it is possible, if the popular election left nobody with an electoral majority, that electors would not agree on any of the three major candidates or a fourth compromise choice.

But if the electors adhered to traditon and followed the popular vote in their respective states, nobody would get an electoral majority. Then the choice of the president would go to the House of Representatives.

Under the 12th Amendment, the House would meet to choose a president from among all the candidates who received votes in the electoral college.Voting in the House would be by state, with each given one vote. If a state's delegation in the House could not agree, the state would lose its vote. A president would be selected only when one candidate won a majority of the states casting votes.

If no candidate gets the necessary majority on the first House vote, the members try again, ballot after ballot, until somebody does (in 1800 it took 36 ballots). And if no majority emerges before Jan. 20, 1981, when the new president is to be inaugurated, the 12th Amendment takes care of that possibility, too.

At the same time the House is voting for president, the 100-member Senate would convene to elect the new vice president. Each senator would get one vote, and it would take 51 votes to choose a vice president. If a new vice president were chosen while the House was still battling over the president, the vice president would become acting president.