Even for golf's preeminent masters, Jack Nicklaus and Tom Watson, today was a rare adventure. Watson experienced its essence on one hole, the 16th. It was there, within a six-hour time frame, that he could see himself losing the Masters to Nicklaus and then getting it back.

They started the second round eight shots apart and ended dead even, Watson after a typically gritty show and Nicklaus after an atypical collapse he all but dubbed Gone with the Wind. Watson's scores were 77-69; Nicklaus' 69-77. Watson was charging most of the back nine; Nicklaus was ready for new left-side rubber, or whatever would get his wobbling wheels realigned.

For the lead after a morning when a mooring would have been useful, Watson needed to leap over 45 players. By day's end, he had whittled that mountainous number to a manageable six. Also two shots behind Craig Stadler and Curtis Strange was Nicklaus, who led the field by three strokes after round one.

"I've used up my allotment of mistakes," Watson thought before his afternoon round.

"I have a little freedom," Nicklaus thought before his.

After sometimes playing like a four-legged animal that barked instead of clawed, the Bear said: "I've done used that freedom up."

The chains were growing tighter in midafternoon when he and Watson walked away from each other on the course but grew closer on the scoreboard. That occurred while Nicklaus was leaving the sixth green after one of his five three-putts and Watson had mustered yet another splendid up-and-down par at the nearby 16th.

Watson was leaning on his putter at the time, clearly satisfied, hopeful if not quite joyous as the Nicklaus bogey was being posted on a leaderboard that had caught his eye. The eight-shot margin was now three--and closing.

What was in Watson's mind earlier at 16, after holing out during the final part of his rain-interrupted first round, would melt a putter. Leading the tournament by a shot on the tee, he took a watery, sandy, miserable triple-bogey 6. He pulled a five-iron into the water, overcompensated and pushed a nine-iron into a trap from the drop area. Then he chipped badly and two-putted.

Wilting Watson bogeyed 17 and 18 for a back-nine 42. Behind him, with a 33 over the same stretch, Nicklaus became the new leader. Came about a two-hour break--and about as much of a turnaround as great players ever experience.

Nicklaus' entire day resembled one of those spin shots to the sloping, slippery greens that have driven everybody crazy. Boldly, he had shot himself beyond all 76 players, then watched in horror as that bite turned into a slippy-slide 38-39 that had him back off the top of the scoreboard by the 11th hole.

Watson is fighting tradition as well as the wind and pin placements on some steeply angled greens that make it a good idea to plug tiny turbos onto the ball before stroking it uphill.

He won two weeks ago at Hilton Head, S.C., which one omen-seeking fan regarded as a disaster. Nobody has won there and here in the same year, an obscure fact that was included in a letter to Watson after he blew a victory there in '77. He won his first Masters later that year.

Also, a Scottish public school named Watsons (not after him) won a major team tournament just before Tom won the Masters in '77 and last year. The guys couldn't come through this year. And no one in two decades has won the par-3 tournament here, as Watson did Wednesday, and also the Masters.

"And no one who's hit a golf ball on the moon has ever won the Masters, either," snapped Linda Watson as her husband studied his pitch on the seventh fairway.

She was feeling well enough to admit that, yes, their 2 1/2-year-old daughter Meg had slipped away with a 4-year-old friend and had been playing in one of the sand traps as Watson was winning the par-3 in a playoff. That's naughty for a regular tournament, sacrilegious here.

"Big boys' sandboxes" Linda calls them to Meg. "Part of Daddy's office."

With the windows open, a wicked draft and rain have put Daddy's office in disarray these last two days, his colleagues swearing during coffee breaks at whoever set up the place this year.

Was Nicklaus surprised to be within two shots of first after that 77?

"I thought I might still be leading," he said. "It's not often that from 12 feet--uphill--I lay up (with a putter). They (the pin placers) are trying. And they're about halfway there."

Patience, nerve and nerves, has been the week-long Nicklaus sermon.

"Nerve enough to play and the nerves to play the nervous shots that have to be played," he said.

Patience is Watson on the fifth fairway during the second round today. His playmates had been long with their second shots, so Watson looked to the swaying treetops right and left for advice. He dawdled for more than a minute, then sent a long-iron to puttable position and escaped with par.

"Some luck," he admitted. Such as that pull-hook on seven that hit a tree and bounced back into the fairway. And the six-iron at 12 that could have landed in the front bunker or worse, in the water. Instead, it hit and stopped on about a three-foot patch of grass between. Sitting up nice and cozy for a fluffy pitch--and par.

This was a deceptive Masters day, close to cloudless and balmy, almost ideal for fans but as ugly as the rains of the first round for the players. Golfers hate wind, for it literally blows much of their strategy away.

Nicklaus scolded Masters officials for creating conditions that "put you in an awful position to make an ass out of yourself . . . about every time you draw it back."

Then he took it all back, saying: "If I had my druthers, I'd rather see it this way (than too easy)." Nicklaus had realized that his complaints in previous years forced a drastic overhaul of the greens. He had helped create this Masters monster; he wasn't sure anyone could tame it.