Searchers trying to determine what happened to a man who disappeared in the Flathead River Sunday conducted an experiment Thursday that was a graphic demonstration of the water's power.

Gabriel Brown, 21, of Kalispell, was last seen by his friends as he swam in the South Fork of the river below Hungry Horse Dam, near a place called Devil's Elbow. That was Sunday evening.

Since then, search and rescue teams, divers, helicopters, airplanes, dogs, and boats have tried to find Brown.

Thursday, rescuers watched as the river sucked in various items intended to track where something entering the river at Devil's Elbow would go.

Diver and sheriff's Deputy Jordan White said searchers rigged packages filled with potatoes, rocks, and transmitters. Potatoes, like people, are composed mostly of water. The 25-pound packages were made to be as buoyant as humans. Transmitters were sealed inside them and they were thrown into the water.

Each of the devices traveled downstream where they entered an area that "sucked them down to the bottom of the river," White said.

The area is a churning, boiling trough, he said, too dangerous for divers to try to explore, but deceptive looking.

"You might not realize it could suck you down," if you are swimming in the area, White said. "It forms a hydraulic [jump] that will push them down."

The potato bundles were sucked down 28 to 33 feet, where they stayed, White said.

Rescuers have wondered if the same thing happened to Brown.

White called the experiment "very successful. It helped us answer some questions."

The divers' work in the search is now concluded unless new evidence is found. A scaled-back aerial and boat search is planned for today, said Undersheriff Mike Meehan.

Reporter Chery Sabol may be reached at 758-4441 or by e-mail at csabol@dailyinterlake.com