The roof of the Spectrum ought to be retractable, just to assure the safety of Julius Erving when he uses occasions such as Wednesday night's playoff against the Celtics to show us what happens to an extraordinary leaper when adrenaline turns to helium.

Surely, the Doctor wll scrape his head or his hand on the tippy-top of the arena some night, soar over Darryl Dawkins' home planet, Lovetron, and jam the ball through the hoop with such force that it bores a hole through the floor all the way to Peking.

That is the only way Erving will top what he did in the third quarter of a two-point Sixer victory over Boston in game three of their NBA Eastern Conference championship series. Even veteran witnesses of Erving's special grace and Dawkins' unique power could not hold back startled screams.

It was a play you'd want included in a sporting time capsule.

From perhaps 15 feet to the right of the basket, Erving had an unmolested jump shot. But he was not put on earth for that mortal a shot, especially with a chance to mentally bury the Celts and just enough room to do it.

Erving hesitated, possibly even walked with the ball, before taking the only dribble he needed. The two Celtic Clydesdales, Dave Cowens and Rick Robey, moved to block his path. Erving cut between them -- and over them, his arm with the ball attached to it whipping from his hip like an out-of-control Ferris Wheel.

The Dawkins dunks sometimes bring baskets down. This one by Erving brought down the house.

Later, Erving sailed high enough to trip over the shoulders of M.L. Carr -- and became properly enraged about a seemingly obvious undercut. There were other dunks other players would consider heroic but were rather tame by Erving's standards. And a few fine assists.

In truth, the Doctor needed every spectacular tool in his bag simply to keep from being the second-best forward on the court. It is possible for a fellow who can leap over tall buildings to be overshadowed. But only by a Bird.

There is a group of basketball ornithologists just about convinced that Larry Bird is the best player on earth. He also is one of the least-articulate athletes ever, but then nobody ever demanded that Sartre shoot free throws.

Bird is the 6-9 embodiment of every basketball virtue -- and this playoff is the stage that will assure the spotlight he so wants to avoid will be riveted on him as long as he stays healthy.

If they were drinks, Erving would be a boilermaker; Bird would be scotch. They bring a sense of history to this playoff, of Russell vs. Chamberlain shootouts. But they no longer guard one another in critical moments, for neither can stop the other.

For three games, no Sixer has found a way to cage Bird, causing the best defender, 7-1 Caldwell Jones, to say: "The only way to stop him is to send him to jail."

Jones drew Bird by default, after the rookie combined for 58 points, 21 rebounds, seven assists, five steals and two blocked shots the first two games.

For much of the first quarter, Jones kept the ball from Bird. Once Bird needed a pick to get off a 22-foot shot. But it went in. And so did three of the four three-point shots he tried.

"That's the best you can do," said another frustrated Jones, Bobby, who also has tried without success to clip Bird.

"His range is the Vet parking lot," said Caldwell Jones. "And he's always in motion.He can shoot the jumper as soon as he touches the ball, which means I've got to react to that and he might go around me."

Even flapping his wings off by himself, Bird is a threat. Bobby Jones once became so involved with keeping the ball from Bird a few feet from the basket along the left baseline that Tiny Archibald slipped down the free-throw lane for an easy lay-up.

It was one of several assists Bird deserved but could not receive. But he had four assists, 22 points and 21 rebounds.

"Don't make no difference who guards me," Bird said. "I've seen it all. I've been roughed and had finesse players on me. I've had bigger guys than me and smaller guys. You know how to play. You just got to go out and play it."

Nearby, assistant coach K.C. Jones volunteered his ultimate compliment -- that Bird "is a natural who hustles." He added: "When was the last time you saw a player who makes $600,000 a year dive for loose balls?

"That's when you feel good, that there's still something to this game (that inspires special talents). He's a combination of a lot of people. A lot of good people. And he works. Even in training camp.

"He's something for kids to look up to."

He's that rare bird who can be subjected to the best defensive adjustments by players quite good at defense -- and still get better.

"but there might be an ironic twist to this series. The classis Boston-Philadelphia playoffs in the past almost always went the Celtic way because they had the superior team. The first three games of this collision, Cowens has not played well.

This time, the Philly Phenom, Erving, seems to have the better supporting players.