The Washington Capitals, whose past entries in the National Hockey League record book have been 100 percent negative, struck a positive note last night. Goals by Mike Gartner and Bengt Gustafsson in the first 30 seconds of the second period wrote history with the fastest pair of scores at the start of a period in the NHL's 63 seasons.

Those two red-light efforts, welcomed with a standing ovation by 12,831 Capital Centre faithful triggered what became a six-goal period, the biggest in the Capitals' 5 1/2 seasons. By game's end, the Capitals had pinned an amazing 7-1 defeat on the New York Islanders, a team carrying a seven-game victory string, a team that had been beaten by Washington only once before in 22 meetings.

The principal heroes were captain Ryan Walter, Gustafsson and Gartner, who played the Islanders' all-star line of Bryan Trottier, Mike Bossy and Clark Gillies head to head and accounted for six Washington goals, five at equal strength.

Walter, who had seemed worn out during Saturday's 1-1 tie with Quebec, was scheduled for a doctor's visit today by Coach Gary Green, to see if anything was wrong. If there is a problem physically, it was not evident last night, as Walter scored two goals -- his first in nine games -- added three assists and was his usual self banging away at the opposition.

"We had something to prove," Walter said. "You outshoot a team (Quebec) 40-16 and only score once and you start wondering if the goals will go in. Then in the first period tonight we don't score and we're still thinking about it.

"But when you break the bubble, things seem to go your way. We broke the bubble quick and we got some breaks -- it looks as if the breaks are starting to go our way. That's very important to a winning hockey team. This one was important to get momentum, too. We're going on the road and we need to get some points there."

Bossy's 32nd goal, off a fine corner feed by Trottier, sent the Islanders ahead on the visitors' first shot after Washington had dominated the early play. The fans could be excused a feeling of "Here we go again." but Washington goalie Wayne Stephenson did not let another puck get by.

Stephenson was especially adroit during a five-shot Islander power play late in the period when another score might have broken the Capitals' spirits.

The beer lines in the corridor still were lengthy when the puck was dropped to open the second period. Walter outdrew Trottier and Gardner picked up the puck. He skated down the right wing and unloaded with a blast past Billy Smith, who was still scratching the resurfaced ice in his crease. With eight seconds gone, the score was even.

"The last game we threw everything we had at them and couldn't score," said Gartner, who netted No. 17 of the year. "Tonight it was just the opposite. Everything went in."

It must have seemed that way to Smith anyhow Gustafsson, standing just outside the right post, deflected Paul MacKinnon's long drive into the net at the 30-second mark and the Capitals were both ahead to stay and enscribed on the plus side of the record book.

Bufalo set the eclipsed standard of two goals in 31 seconds, registered at the start of the third period against the New York Rangers in 1974.

Washington was far from finished. A drive by Bob Sirois was smothered by the New York defense. but Paul Mulvey coralled the rebound and backhanded the puck past Smith at the 58-second mark. It was Washington's third score in three shots and Mulvey's first goal in 13 games.

Smith finally made a save, blocking Walter's deflection of another MacKinnon drive, but Walter bagged the rebound at 4:14 for a 3-1 margin.

The fans, reveling in the unaccustomed scoring, responded by chanting the call usually aimed at a struggling Capital outfit: "One two-three-four, we want more." And sure enough their joy was not ended, because more was forthcoming.

MacKinnon, the youngster who played for Winnipeg in the World Hockey Association a yeaar ago, blasted a 50-footer over Smith's left shoulder at 9:08 for his first NHL goal and a 5-1 lead.

Those first five goals were scored with both teams at full strength. The Washington power play, successful only twice in its last 28 appearances, was given a chance and it clicked, too. Alan Hangsleben, moving unopposed from the right point, fired from fairly close range and Walter deflected the puck past Smith at 13:16 for the Capital's first six-goal period. He announcement of that record brought yet another standing ovation.

"These fans are incredible," said Coach Gary Green. "That's why we've said right from the start that if this team was competitive, the fans would be with us. They are with you more than any other team in the league if you give them their money's worth."

Gustafsson gave them another pocketful of good tidings by skating past most of the New York team and depositing the puck behind Smith at 1:02 of the third period. It was the third two-goal game for the Swedish rookie, the others coming in the first 10 days of the season. Later, Gustafsson needed treatment for a bruised left forearm, the customary problem of Swedes who anger the opposition.

Gord Lane, the Islander defenseman who walked out on the Capitals earlier this year and savored two New York victories over Washington at Nassau Coliseum was angry enough in the final period last night to take a 30-foot run at defenseman Pierre Bouchard, cross-checking Bouchard intothe boards.

Lane was hooted unmercifully as he skated to the penalty box, while Bouchard disdainfully shrugged it off and said, "It just made a lot of noise."

Smith accepted his fate without visible mortification saying, Why get angry? They weren't bad goals. Give credit where credit was due. They played well. I'm glad I didn't get angry or it might have been 20."

While the forwards racked up most of the points, the Capitals' defensive performance was exceptional too. The Capitals went the route with two pairs. Bouchard and Hangslebne, MacKinnon and Rick Green. Robert Picard, who sat out the Capitals' 6-4 victory over the Islanders a year ago, was an absentee with the flu.

"Before we had Hank (hangsleben), we were in trouble playing a game without Pic or Greener, Gary Green said, "But (GeneralManager) Max (McNab) couldn't have supplied a better defenseman to round out our five. There may be better defensemen than Hank but he's got the right type of balance for us and he's a very solid defenseman."

Green altered the Capitals' usual pregame routine. He canceled the normal morning skate, then herded the players into the recreation room 1 hour 45 minutes before game time to conduct the meeting usually held in the dressing room 90 minutes before the first faceoff.

"They spend so much time in the dressing room that I wanted them to get away into a more relaxed atmosphere," Green said. "I thought they could absorb it there and take it into the room with them.

"I was afraid to have a pregame skate, because I thought we played so well yesterday. We just didn't put the puck in the net. I tried to psychologically get them out of the third period yesterday into the first period tonight."