Times were tough on the tundra, so Eskimos practiced magic in the hunt, entreating the spiritual power of caribou and seals with weapons carved in their image. Falcon feathers gave arrows the speed of the bird; a seal scratcher, made of real claw, mimicked the noise of the animal on ice. And carved masks of spirits with pierced hands allowed the inua, or spirit of unborn animals, to pass through and replenish the species for future hunters.

"Inua: Spirit World of the Bering Sea Eskimo," opening at the Museum of Natural History on Friday, explores the mythology, artistry and cultural quirks of an isolated people. Hunting implements from the 1870s dominate, but household items, spiritual masks and a range of more recent made-for- trade artworks round out the show, here for seven months.

Eskimo means of making do -- living in underground houses in winter, digging holes in the ice and getting around by kayak or dogsled -- are displayed as expected. What's striking are the magical motifs decorating utilitarian objects, down to the last harpoon cord attacher and thimble guard. Even a fish club was made in the form of a seal with inlaid ivory eyes and finely incised whiskers and lashes.

"They had a lot of time on their hands," explains anthropologist William Fitzhugh who, with Susan Kaplan, spent the past year organizing the show. Both curators credit Edward William Nelson for his research. Just 22 when he arrived in what's now Alaska in 1877, Nelson spent four years cataloguing, photographing and eventually buying the objects for the Smithsonian. (He paid in chits from the trading post, earning a reputation as "the man who buys good- for-nothing things.") Nelson turned up an amazing variety of harpoons, spears, darts, lances, bolas (for low-flying birds), and bows and arrows. The artifacts have been in the museum's attic for a hundred years.

Things were different then, before whites and money invaded the region. The high point of the religious calendar was the December bladder festival, when the bladders of all the seals, walruses and white whales killed that season were chanted over and then given back to the sea. It all had to do with inua -- the spirit in every plant, animal, rock and human, believed to live on after death.

Fashion was functional: A jacket of seal intestine is thin as Saran Wrap. It's completely waterproof, Kaplan notes, sewn with a double stitch so the material is never penetrated. Dogskin mittens were good camouflage. Goggles were a must, snow blindness being an occupational hazard. Fittingly, certain ceremonial masks show spirits in goggles.

Some things never change. It was a man's world, with separate men's houses where shamans conferred on spiritual matters, war and peace. They smoked, brushed up the tool kit and compared myths while women made baskets and sealskin alterations.

A final section jumps ahead to masks made as 20th-century wall-hangings and even some protest art. But the best art was made unself-consciously, whittled while waiting for the bladder festival.

"INUA: SPIRIT WORLD OF THE BERING SEA ESKIMO" -- At the Museum of Natural History through January 2.

PERFORMANCES & CRAFTS -- A dozen Eskimos from the Bering Sea village of Sivuquq will perform traditional dances in the museum's first-floor rotunda, Friday at 1:30 and 3; Saturday through Tuesday at 2 and 3:30. Demonstrations of ivory carving, skin sewing, dollmaking and games on the ground floor, Saturday and Sunday, noon to 2 and 4 to 5; Monday and Tuesday, noon to 2.