Tuesday, July 6, was a gorgeous day. The sun bathed the streets surrounding the statehouse, the humidity was tolerable and a summer breeze blowing off the Severn River made the afternoon and evening lovely and comfortable.

For Maryland's politicians, it was a perfect day to come to their winter playground to frolic for an evening. The occasion: the final day candidates could file to seek elective office in the 1982 elections.

Filing day is a rite, as much a part of Maryland political tradition as Senate filibusters during the last hours of the legislative session. Since the state Constitution states that all a candidate has to do to file for office as a Democrat or a Republican is be a registered member of that party, no one knows who will show up before the 9 p.m. deadline to file.

As a result, the scene in the elections board is inevitably chaotic as the deadline approaches. The politicians are everywhere, eyeing the bulletin boards where the filings are posted, eyeing the television cameras and eyeing reporters and each other. In spite of the yeoman efforts of elections board supervisor Willard Morris, the aisles are clogged. In the last moments before the doors are locked to keep any post-deadline candidates out, Morris treats everyone exactly the same. One minute he will shove a reporter; the next he will shove U.S. Rep. Roy Dyson (D-1st Dist.). To block the aisles is to invite Morris' wrath.

"It's his one day of the year to act pompous," said one delegate.

Rumors and surprises are the staple of filing day. This year was no exception. Moments before the doors were shut Mike Curtis, the former Baltimore Colts linebacker, walked in and, almost unnoticed, filed as a Republican candidate for the U.S. Senate. Ross Z. Pierpont, who ran for governor as a Democrat in 1966, switched parties in 1970 and then ran for governor as a Republican in 1978, filed at the last moment to keep Robert A. Pascal from being unopposed in his bid for the GOP governor's nomination.

Pierpont is not likely to be a serious challenger to Pascal. But his presence in the race means that the Republican National Committee, which has pledged to stay out of contested primaries, cannot begin diverting any funds to Pascal before Sept. 15, the day after the primary. Thus can a seemingly meaningless act have a good deal of meaning.

Perhaps the most surprised man in the old armory building that serves as the election board's headquarters was state Sen. Thomas P. O'Reilly (D-Pr. George's). The two-term senator was leaning casually against the wall near the bulletin board that listed him as unopposed for reelection shortly before 9 p.m. Suddenly, one of the 24 staffers (10 more than usual) on the job posted a name opposite O'Reilly's. O'Reilly blinked back surprise. It was Robert S. Redding, the chairman of the county's House delegation, a man he had expected to run on a slate with, not against.

Hours later, sipping a beer, O'Reilly ran into the head of the county Senate delegation, Sen. Thomas V. Mike Miller.

"What do you think about Redding?" O'Reilly asked.

"Bob Redding's a good man," Miller answered.

"I know that," O'Reilly said. "But why is he running against me?"

Miller laughed. Then he realized O'Reilly was serious. He had not heard the news. He sat down, shaken.

"Bob Redding was the voice of moderation in that delegation," Miller said. "He was the one guy who could talk to everybody, reason with anyone. We're really going to miss having him over there."

Miller and O'Reilly then huddled to discuss strategy. Their fervent hope is that Gov. Harry Hughes will keep an O'Reilly-Redding race from happening by guaranteeing Redding an appointment to the Workmen's Compensation Commission, the job he has wanted all along.

This was a night for sitting around and speculating about the races that were now locked into place.

Baltimore Sen. Harry J. McGuirk was indeed challenging Gov. Harry Hughes, with incumbent Lt. Gov. Samuel W. Bogley as his running mate. Bogley spent the last four hours before the filing deadling in the elections board just in case McGuirk had a last-second change of heart.

Even after the deadline, Bogley was still hanging around. "I'm not leaving until he does," Bogley said with a laugh, pointing at his running mate, who was holding court on the other side of the room.

Everywhere there were candidates: unknowns, heavy favorites and names out of the past. Dale Anderson, the former Baltimore County executive who left office after being convicted on federal corruption charges, filed to run for the House of Delegates. A husband-wife team filed for governor and lieutenant governor. Pascal and Curtis could form a ticket consisting of former Duke University football stars. And Louis L. Goldstein is running for a seventh term as state comptroller.

In Harford County, no fewer than 20 persons filed to run for three available seats in the Democratic Primary in the 35th District. Prince George's county's 21st District was a weak second with 14 candidates.

"We faded at the end," said Del. Thomas J. Mooney, one of three incumbents in the 21st.

What does it all mean? Not very much, beyond the fact that an awful lot of people would like to hold elective office in Maryland. But for the established politicians, the ones whose campaigns started long before the filing deadline, the last hours were a chance to have a few laughs, take a deep breath and look around them at compatriots who may not be back next time around.

The filing deadline is to an election what half time is to a ball game. Now the second half begins. And everyone knows no ball game is decided until the second half.