Dressed in a woolen winter uniform and girdled to a perfect V by a surgical corset, Sp. 4 Edward L. Powers paces the mat before the Tomb of the Unknown Soldier with mechanical precision, oblivious to the 92-degree heat.

"Today is what we consider one of the nice walking days," he said.

For his $160-a-week salary, Powers will lose three or four pounds a day walking the mat in the searing heat that melts the polish off his boots and makes a sponge of his corset. He must soak his white cotton gloves so that his well-lacquered rifle doesn't slide through his hands, and only when his sunglasses threaten to slide off his sweat-slippery nose may he leave the mat to readjust them.

"I can tell when there's a big crowd out there. You can feel them breathing up the fresh air," he said.

"I hate day work in the summer," said William E. Hall, a policeman who rides a motor scooter. The recent weather, coupled with even-hot asphalt, blasts of heat and pollution from cars, and a strap-on helmet generally keep him wet with sweat. "Sometimes I go into a liquor store for a couple of minutes and go back to the walk-in refrigerator just to let my helmet cool off," he said. He goes through two shirts a day, he says, and still can't keep the collar clean. Hall checks on banks frequently, signing a log and enjoying the respite from the heat. "Those people with air conditioning have it made," he said. Still, he says he has "a good job" and wouldn't do anything else.

Down in the dark and suffocating bowels of the Presidential Hotel's boiler, sweat fell like raindrops from the sooty forehead of 28-year-old Bill Lanier as he hammered and welded.

"This's a cool one," said broiler-maker Lanier, who had crawled inside the 120-degree boiler through one of its two-foot square windows. It gets hottest, he said, when there are two boilers and one is kept burning while the other is being repaired. "Then it can get up to 180 degrees," he said. One day last week when he emerged from a boiler he was repairing to take a break, Lanier said, "People were complaining about how hot it was outside. I had gone out to cool off."

But Washington's heat wave does make a difference to Lanier's job, one of the most extreme in town "as far as hot and dirty goes, I don't work as fast as I usually do when the weather is livable," he said.

Lanier's assistant periodically handed him a rag to wipe his brow and a pitcher of ice water to sip. He takes salt pills regularly, he said.

A boilermaker for seven years, Lanier learned to weld in the Army and despite the heat he says he likes his job. "Sometimes there are elderly people in a building and they have no hot water. I don't think anyone like getting inside these things, but nobody else will do it."

About 18 months ago, Lanier said, he fainted on the job and admitted that "I've gone to sleep in 'em. Ain't nobody gonna come and wake you up."

Lanier's face was besmirched, with soot and his clothes soaked with grime and sweat as he grinned out from the boiler lit by a naked bulb. Sweat dripped from the blackened ends of his otherwise blond hair at the edges of his work-hat.

"You just keep a cool mind - if possible," he said.

It was 86 degrees with 66 per cent humidity when Dick Crealy and Tim Gullikson took to the court at 1:26 p.m. yesterday in the Washington Star International tennis championships. Two and one half hours later Crealy came off the court, drenched and victorious. The temperature had climbed to 91.

His striped shirt clung to his body, a combination of sweat and water he repeatedly poured over his head and neck. He sat puffing while ball boys poured more water over him and hand him soft drinks and glasses of water.

An hour after the match Crealy was still dripping. "This heat just keeps the perspiration coming out of you, he said. "You can't get dressed" because your clothes would become soaked again.

To counter the heat, Crealy is eating a lot of foods with salt in them - potato chips, popcorn, etc. but he isn't taking any salt tablets or vitamins. "The main thing is to keep your fluids up," he said, and try and stay cool.

He shook his head. He had only 10 minutes left to "cool off and relax." He was playing doubles at 5 p.m.

"The humidity is so bad I feel like I've been locked in a closet," said John Lauterbach, who was selling roses, carnations and marigolds from his stands at 15th and M streets NW. "You sit down and you sweat, you stand up and you sweat. I keep sprinkling water from the flowers on me." He survives, he says, by keeping his stand in the shade of tall buildings. "Sometimes regular customers come back from lunch and bring me ice tea." Still, he took Monday and Tuesday off because it was too hot.

A cook has one of the hottest jobs in Washington. "What did the President say - 'if you can't stand the heat, get out of the kitchen,'" Jean M. Picard, head chef at the Madison Hotel, asked as he and his assistants moved between a broiler cooking at 450 degrees and the boiling water of a steam table. "When a new man comes and tells me it is too hot, I tell him to go home. If it is too cool in here, then the food will be cool."

Roosevelt Davis, working with chunks of London broil and dripping with perspiration, says his white chef's smock stays wel all day long, but he has become used to it. Despite this year-round tropical working conditions, he says he finds it hotter outside now. "I think it's because of the sun beating down on your head," he said."I try to stay out of it."

Walter Roberts, 29, handles perhaps several hundred pieces of other peoples' clothes each day in his job as a presser at the Mayflower Valet on Vermont Avenue N.W. Working next to a steam machine on which he hangs coats and jackets for dewrinkling, Roberts sweat profusely. The cleaning plant is not air conditioned and fans just move the hot air around a bit, he says.

"It makes you tireder and lazier," Roberts said with a shake of his head. "But you get used to it."

Roberts fights the heat by stopping periodically for a cold beer, and by trudging up the stairs to the air conditioned government offices on the floor above. "I just go to the rest room or stand around in the hall for few minutes," he said.

If you think you're hot, imagine how Barney Rubble feels as he roves around King's Dominion near Richmond, dressed in a 40-pound Flintstone character costume.

"It's about 30-40 degrees hotter inside the costumes," said live shows operations manager Jan Schidt. "I lost 20 pounds one summer doing it. Most of these kids are high school or college athletes so it's pretty good for them. They get used to it after a while. It get 'em in shape."

Barney is one of several cartoon characters who walk around the amusement park for about 20 minutes and then have 70 minutes break. "They take salt tablets and drink a lot of ice water," Schmidt said.

Mike Taylor, 17, plays Barney Rubble. Last week he was told he fainted on a bench in front of a group of children, but he doesn't remember for sure and his boss never heard of the incident.

"All I remember is getting dressed in the costume and feeling dizzy as I was walking out.Later (someone) told me I just lay down on a bench for a half hour. I don't remember it. I'm going to see a doctor because I've been dizzy all week," Taylor said.

Mike Coakley, 18, wears a 15 pound green for costume and a fireman's helmet in his role as Fleegle, a dog from "The Banana Splits" cartoon show. "I've been eating a lot more, about four or five times a day. You lose so much energy that (I) eat a lot of stuff like french fries for the salt."

"A lot of people ask if the suits are air-conditioned like at Disney World, and how can we stand it. It gets monotonous after a while."

"We just stink a lot and lay down all the time on breaks. But we're pretty persistent and the pay is good ($23 per day) so nobody's quit yet," Coakley said.

As they walked slowly across the hot pavement in front of Columbia Hospital for Women yesterday, an obviously pregnant Andrea Brewer squared her shoulders and invited her husband, William, to buy her a drink.

The Rockville couple, with four boys at home, had just learned that they can expect twins in the fall.

Mrs. Brewer was taking this news in stride, as she had taken the heat wave and everything else. She is continuing to work full time, she said, "in the house."

Her four youngsters are no extra trouble in hot weather, she said. "Kids are kids. You just take 'em out and squirt 'em with the hose."

As for her own delicate physical condition, Mrs. Brewer said, the heat "causes more swelling, and you get tired more. You try to stay in as much as possible . . . If you don't run around crazy, you survive.

A District taxi driver in a jaunty cap said he was working yesterday only because he had promised to teach his friend from Mongtomery County the District taxi routes. His cab had no air conditioning.

"I'm sick at my stomach," moaned the friend in the front passenger seat as they stopped to pick up a fare. The taxi was like an oven.

"A lot of the fellas (taxi drivers) don't work in July and August," said the driver, who did not want to be quoted by name.

He doesn't have air conditioning because he got this "very durable 1966 Plymouth with a flat six engine for such a good price," he said.

He does lose the money he saved on the car by not working when it's hot. "Yeah, but I get to stay home and goof off. It all evens out."