The Washington Capitals climbed into double figures for the first time in their history last night. Rolling up an 8-1 lead before the midpoint of the game, the Capitals destroyed the Philadelphia Flyers, 10-4, to the unrestrained delight of those among the crowd of 15,134 who did not face a postgame ride back to Philadelphia.

Coach Bryan Murray had promised that a record would fall. He meant, however, that the Capitals would beat the Flyers for the first time in 16 meetings at Capital Centre. Nobody in his right mind could have envisioned the slaughter that ensued.

Dennis Maruk and Tim Tookey recorded hat tricks, the first time two Capitals had managed that feat in one game. Maruk added three assists, to tie the club record of six points in a game. Greg Theberge collected two goals and three assists, to match the club mark for a defenseman.

The big record as far as Murray was concerned, though, was five power-play goals. It had to be gratifying to a coach who took over a team with a dreadful extra-man play and made it so effective so quickly.

"It was just satisfying to see them play like that," Murray said. "The power play was well organized and it was so deadly that at the end of the game the Flyers couldn't seem to do the things they usually do."

Philadelphia was assessed 23 penalties totaling 68 minutes, to Washington's 15 for 36. The teams meet again in Philadelphia's Spectrum tonight at 8 o'clock and it would be reasonable to expect the Flyers to come out with elbows, sticks and fists flying to try to reverse last night's humiliation.

"Whether humiliated or not, they're tough in their building and they will be tough tomorrow. But they've got to respect that we'll be tough on the power play. If they take bad penalties, we'll punish them, if that's the right word."

The Flyers took some bad ones early last night and two power-play scores in the first 2 1/2 minutes had them so rattled that Coach Pat Quinn called what must have been the earliest timeout in NHL history, at 2:27.

"We've gotten down early in a lot of games lately," Quinn said. "But a couple of goals in today's style of game is basically nothing. I wanted to collect our thoughts and go on from there."

The Flyers needed to collect their thoughts. Paul Holmgren, dumped by Washington captain Ryan Walter, retaliated with an elbow and was chased at 33 seconds. Four seconds later it was 1-0 as Maruk won a faceoff from Clarke and skated in to deflect Darren Veitch's shot from the right point.

Clarke, who was not ready for the faceoff, complained and was assessed both a minor for unsportsmanlike conduct and a 10-minute misconduct. While he was off, Jim Watson was chased for interference and Theberge used the two-man advantage to connect on a 50-footer, after Maruk again won a key draw from Bill Barber.

Not long after the timeout, Mike Gartner raced down the right wing, faked a shot to pull goalie Rick St. Croix out of the net and fed Tookey for a shot into empty cords.

Before the period was half over, Theberge had scored again, on another 50-foot blast. This time Bengt Gustafsson got around defenseman Glen Cochrane and tried to feed Maruk in the slot. Maruk missed the puck, but Theberge pounced on it and unloaded without hesitation.

For Washington, a four-goal lead is no reason to celebrate. So there was a murmur of apprehension when Reg Leach put Philadelphia on the scoreboard early in the second period. But it disappeared with further elation as the Capitals scored four times in 4 minutes 9 seconds and removed all doubt from the outcome.

Veitch utilized another two-man advantage to score his first goal of the season at 5:38. Tookey connected from the right-wing circle at 5:38 and then, at 6:40, came one of those plays that are worth remembering a long time.

Walter knocked Holmgren off the puck behind the Philadelphia net and Gustafsson picked it up. He circled along the side boards toward the blueline, then cut into the slot, all the while with Flyers hanging on him. Finally, he pushed a one-handed pass toward the crease and Maruk batted it home at 7:19.

Tookey completed his hat trick at 9:47, converting Rick Green's pass after Gaetan Duchesne's check jarred the puck loose from Flyer Brad Marsh.

That was the first three-goal game in the NHL for Tookey. Maruk earned his ninth hat trick at the 17-second mark of the third period, taking Gustafsson's pass and sailing in to beat St. Croix.

Rookie Bobby Carpenter was the one who made the game a '10.' Theberge, who refrained from gunning for a hat trick to set up Veitch earlier, did the same once more to feed Carpenter and complete the Flyers' humiliation.

The Capitals had been beaten by the Flyers by scores of 11-2 in 1976 and 9-2 in 1977 and 8-1 as recently as January at Capital Centre, so a lot of frustration was shed with this effort. Murray declined to remind his troops to cool it in anticipation of a tough rematch tonight.

"Some of these guys have been here a long time and experienced the rest of it," Murray said. "I want them to enjoy this. I want them to be loose and be happy and appreciate what happened here tonight."

One who appreciated it was Maruk, a 50-goal scorer a year ago who never has been fully recognized as one of the stars of the sport, because he always has toiled for also-rans.

"It makes everybody feel good," Maruk said. "They're hurting, but they're a good hockey club and they didn't quit. We struck early with a couple of power-play goals and Davy (Parro) made some big saves and they couldn't come back.

"Personally, it's great to find the net. This has been a pretty successful line since Bryan put us together and Gus and Walt really do a great job. All the lines Bryan has picked are playing well and I just hope we keep it going."

The Capitals were not concerned about the Flyers seeking revenge tonight.

"Our policy right now is to let them worry about us," Theberge said. "They've got to concentrate on winning, but we want to win, too."