John David Dingell Jr. loomed in the chairman's seat in the center of the back row, ordering the various species of congressional power-sniffers to sit down and shut up. "The chair means exactly what the chair says," he informed the whispering collection of lobbyists, lawyers, staff aides and trade journal scribes. As his prosecutorial voice resounded through the hearing room, as his gavel fell with the force of a General Motors piston, as his sharpshooter eyes focused on the targets of his displeasure, it became clear why they call this man Big John.

The committee work of the 98th Congress was beginning a few minutes after 3 p.m. on Feb. 3, and few members of the House of Representatives had a deeper sense of the institution, or more respect within it, than this Polish lawyer from the industrial suburbs of Detroit. A former cloakroom page and son of a New Deal congressman, Dingell had served in the House for 27 years.

Now he was chairman of the House Committee on Energy and Commerce, the oldest committee on Capitol Hill, the old power base of former House speaker Sam Rayburn, the committee with the largest budget and staff in the House. In a universe where 435 egos soar and collide, burn bright and burn out, Dingell's committee is a galaxy of its own.

Energy and Commerce is where the investigation of the Environmental Protection Agency began, where the debate on pricing of natural gas will be waged, and where, day after day, crucial decisions are made affecting everyone who breathes, drinks, eats, smokes, watches TV and movies, listens to the radio, drives, plays the stock market, needs medical care, pays for insurance, enjoys sports, worries about hazardous waste and nuclear power plants, buys faulty products, rides the railroads or gets buried.

While the committees that tax and spend--Ways and Means, Appropriations and Budget--appear from the outside to be the power centers of the House, many on the inside covet Energy and Commerce above all others. Every session of Congress, it has one of the longest lists of freshman applicants, and the campaigns they wage to gain seats on the committee are equal in intensity to their election races.

Its six subcommittees, regarded as among the busiest and best-staffed on Capitol Hill, present unending opportunities for members to get their faces on television and their names in the press as they confront corporations and federal bureaucrats. Its broad jurisdiction offers them the chance to deal with issues of great importance, both to voters back home and monied interests who bankroll their campaigns. Its members include 10 of the top 50 recipients in the House of money from political action committees, which has prompted Fred Wertheimer of Common Cause to refer to it as "PAC Heaven."

With a few exceptions, Energy and Commerce is populated by cocky, aggressive workaholics. Said former Alabama congressman Walter Flowers, now a lobbyist in Washington: "Commerce is where the action is and the guys are bristling with it. They are the ones asking the questions and getting the answers. The important issues are theirs, and they know it and the rest of Congress knows it. They've got a certain swagger."

The pride of Mike Synar, a third-term Democrat from Muskogee, Okla., is typical of many of the younger members. "Commerce has a unique personality," he said. "You spend an enormous amount of time with the members. Every day there's something on the committee that you've got to do. Other committees aren't like that. You get so close to the people, from 9 in the morning to 9 at night. You know who's pregnant, who's having an appendectomy, you know everything about them, like a family. We're the best show on the Hill."

Periodically over the coming months, The Washington Post will search for some answers to how the modern Congress works--and for whom it works--through a series of occasional articles on the House Committee on Energy and Commerce, a diverse and colorful universe encompassing 42 representatives--nearly 10 percent of the House--their friends and enemies, backgrounds and home districts, along with 200 staff analysts and political advisers, and scores of federal bureaucrats, business lobbyists, and consumer activists.

In many ways it is a universe that reflects the character of the force at its center: Big John.

John Dingell, 57, is a unique figure in the House. He is not close to Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.), or Majority Leader James C. Wright Jr. (D-Tex.), or Ways and Means Committee Chairman Dan Rostenkowski (D-Ill.), or any of the other Democratic committee chairmen. But he is as powerful as any of them--many say more influential--and is respected by almost all of his peers for his ability to treat his enemies fairly, move legislation, deal with the Senate, and protect, if not expand, his turf.

"John Dingell feels about his committee much as Lyndon Johnson felt about his ranch," said Tom Tauke, a Republican from Dubuque, Iowa. "Johnson didn't want to own the whole world, he just wanted to own all the land surrounding his ranch. Dingell doesn't want his committee to have the whole world, just all the areas surrounding its jurisdiction."

"Sometimes I think he is an arbitrary and capricious son of a bitch, and other times I think he is a great parliamentarian. At all times I'd much rather have him on my side than against me," said Republican Edward Madigan of Lincoln, Ill. "Dingell is formidable not because he has more friends than anyone else, nor because he is more skilled--there are others as skilled as he. His strength comes because he takes the skill he has and combines it with good staff work, a thorough knowledge of the issues and a bulldog determination not to let go. He is the most tenacious member of Congress."

He is also one of its most complex members, both in terms of ideology and style.

In the 1960s and early 1970s, when he wrote legislation protecting endangered species and marine mammals, Dingell developed a national reputation as an environmentalist. But, from 1977 to the end of the last session, when he pushed the interests of the Detroit automotive and steel industries in the long-running dispute over clean air standards, his standing among the environmentalists diminished. One clean air group called him "Public Enemy No. 1," and wore T-shirts to his hearings that bore the slogan "Dirty Dingell."

Yet today, as the leader of his committee's highly publicized inquiry into the Environmental Protection Agency, he is emerging again as a congressional defender of the earth.

To one extent or another the actions of most congressmen are related to the interests of the districts they represent. In Energy and Commerce, those relationships are well defined.

Republican Thomas J. Bliley Jr. of Richmond, for instance, uses the committee to defend the interests of the tobacco industry. Every year he tries to kill a bill that would require more and larger warning labels on cigarette packages and advertisements. The dominant artwork on his office wall is a sketch of the Phillip Morris plant in his district.

Democrat Thomas A. Luken of Cincinnati uses the committee to defend the interests of Procter & Gamble, a home-town soap conglomerate that has taken an active role in trying to weaken the clean air and consumer product safety laws. "P & G is Cincinnati and Cincinnati is P & G," explains Luken.

Republican Jack Fields of Houston, whose district along the Houston ship channel contains the largest petrochemical complex in the world, uses the committee to promote the oil and gas industry. The first thing one sees upon entering his office is a colorful row of hard hats from the plants in his district: Merichem, Gray Tool, Goodyear, Diamond Shamrock, Charter International, Du Pont, Tenneco, St. Regis, Phillips 66, Shell, Armco, Gulf, Ethyl and Exxon.

In Dingell's case the interests are what the current lexicon calls "Smokestack America": the big auto companies, tool and dye firms, and chemical and steel plants of Detroit and Dearborn.

Dingell's second wife, Deborah, comes from one of the big auto families of Detroit and works in the governmental affairs office of General Motors in Washington. Two sons are auto engineers in Detroit. When Dingell's longtime legislative assistant, Robert M. Howard, resigned earlier this year, he quickly landed a job with Ford Motor Co.'s office in Washington.

Dingell is known as the automakers' best friend in Washington, the legislator they turn to for help on issues such as the auto emission standards of the Clean Air Act. "Somebody has got to represent the goddamn auto industry," he says, and his liberal colleagues on Energy and Commerce understand what that means.

"We probably agree with him 80 to 90 percent of the time," said Democrat Edward J. Markey of suburban Boston, "but when it comes to talking Detroit issues, he gets a mindset that is immutable."

Frank M. Potter, the committee's chief of staff, has worked for Dingell for 12 years and considers him a close friend. He thought Dingell was on the wrong side of the clean-air fight and told him so many times. But the trust in their relationship remained implicit. He explained the many sides of his boss this way:

"John Dingell not only tolerates but welcomes dissent. Some staff members work more closely with him on the auto issues, the Michigan economy issues, than others, but there is no orthodox view within the staff. We get into long arguments with him and among ourselves. Is this good policy? Is it good for the country and not just good for Michigan? Sometimes we win with him and sometimes we don't. But it is not the kind of place where there is a party line and you have got to adhere to it.

"He is just not a simple man. He's a hard man to read. I guess the only way to explain him is that he is a child of the House, he was a page and he has been here virtually all of his adult career. He has a very deep reverence for the institution, but he also loves to fight. On one level there seem to be contradictions, but fundamentally there are not."

Democrat Timothy E. Wirth of Denver, who has served on Energy and Commerce since 1975 and now runs one of its subcommittees, put it this way: "A lot of people come up here and get burned out, but not John. He just gets stronger. He is now the best legislator in the House. The reason for that is his remarkable capacity to live with ambiguity, which you have to do up here. You just have to. The world isn't simple, there are so many competing interests, each with a bit of the truth. If you try to stake everything out in terms of black and white, it will kill you. The ambiguity of our system is in a way summed up in Dingell, who handles it with great aplomb."

Outside of his families--the legislative one in the Rayburn House Office Building and the personal one at home in northern Virginia--Dingell has two passions which help define this ambiguity. One is hunting. He will hunt almost anything, anywhere, with anyone who loves the sport as much as he, even some of the federal bureaucrats in the Department of Energy who, most of the time, in political terms, find themselves on the other side of his staff's loaded rifle. When the elk season arrives, Dingell heads for Colorado. When turkeys are in season and Dingell's aides have a hard time locating him at mid-morning, they know he has slipped out of his office to hunt with a few of his buddies. But perhaps even more than hunting, Dingell loves to go to the Kennedy Center at night to watch ballet.

At work, the burly, 6-foot-3 Dingell sometimes appears a frightening creature who is not to be crossed. One Pennsylvania Democrat had the misfortune last year to ride in the same subway car with him from the Capitol to the Rayburn Building only minutes after he had stood up to oppose him on a procedural question on the House floor. He said he aged 10 years during the 40-second trip as Dingell raged against him.

A few years earlier, one of Dingell's aides got on the elevator with Frank Thompson of New Jersey, then the chairman of the House Administration Committee. Some House leaders were trying to strip Dingell's committee of its energy jurisdiction at the time, and Thompson was asked which side he was on.

"I'm with Dingell," said Thompson.

"Why?" he was asked.

"Because he remembers, that's why."

Democrat W.J. (Billy) Tauzin of Thibodaux, La., says he will never forget the day in February when Dingell attacked an EPA official who was testifying before the committee and kept turning to his counsel before answering any of the questions. "God, did he chew that guy out," said Tauzin. "He scared the hell out of everybody in the room. He banged that gavel so hard I went over to him a few minutes later and said, 'John, we just got a report that there was an earthquake in California, hundreds have died, and there's a warrant out for your arrest."

For a man who loves to fight--nothing brings more sparkle to his eyes than recollections of old congressional battles--Dingell is not without sensitivity. His aides often get phone calls late at night from the boss, who wants to go over the rulings he made from the chair that day. "Was I fair?" he asks them.

In February, when the EPA investigation was at its peak, Dingell began one of his morning discussions with his staff by worrying about whether anything Congress was doing had the taint of McCarthyism, whether they were making any accusations that could not be proved.

His colleagues on Energy and Commerce say that often Dingell's I'll-get-you demeanor is just a posture he assumes for political leverage: he wants people to think he will get back at them. Last year, he fumed and fussed when most of the Democrats on Energy and Commerce opposed his effort to revise the Clean Air Act.

"It got nasty. Boy, it got nasty," recalled Synar, who attempted, without success, to be a conciliator in that fight. "I sat in the front row, directly below him, and the spit was flying and it was landing on the back of my neck."

But when many of those same committee members turned to Dingell for help on other issues, he was there.

"I thought I was really in the doghouse after I worked against him on clean air," said Democrat Ron Wyden of Portland, Ore. "He had to be less than delirious with joy with me. And yet a week before the session ended, I asked him to help me with a minor bill that would be of great benefit to a small town in my district that wanted to get rid of federal regulation of some dinky little dam. John took it as one of his own, as though it was the most important thing in the world, and bulled it all the way through the House in the space of a few days."

As feared and respected as Dingell is, Energy and Commerce is hardly an autocracy. When he took over in 1981, in fact, he found himself at the head not of one committee but of six subcommittees that were almost totally independent of the chairman.

His predecessor, Harley O. Staggers of West Virginia, whose field of interest at times seemed limited to the railroads, coal and honeysuckle roses, had been rendered virtually powerless by a group of aggressive subcommittee chairmen led by Dingell and his closest legislative colleague, then-Rep. John E. Moss of California. They voted no-confidence in Staggers, stripping him of his chairmanship of the oversight subcommittee, of his power to hire and fire, to set the subcommittee agendas, even to assign parking spaces.

"When we got here it was just a series of baronies, with no communications between them," said Potter. While Dingell has been able to reclaim some of the prerogatives of a chairman in the last two years, the men who run his subcommittees are still quite independent.

"John inherited the boundaries he helped create," said one of his aides. "The business of restoring the traditional structure of a committee is not easy. Once you've let the quicksilver out of the thermometer you'll never get it all back in."