After a century in a Smithsonian attic, the world's largest and most important collection of Eskimo art and artifacts finally has come to light in a revealing new show at the National Museum of Natural History/National Museum of Man.

Titled "Inua: Spirit World of the Bering Sea Eskimo," it includes some 600 ivory carvings, bowls, baskets, clothing and carved tools and hunting and fishing implements used by the Bering Sea Eskimos of Alaska between 1877 and 1881, shortly after the United States acquired the territory. Brimming with beautiful objects--from tiny carved ivory needle boxes in the form of a seal to large, scary spirit masks carved from wood--this large, didactic show offers a rare slice of Eskimo life and art as it existed before the white man's incursion.

It also dispels a persistent stereotype: All Eskimos didn't--and don't--live in igloos and subsist on whales.

As it happens, whales bypassed the Bering Sea Eskimos on their way further north to the Polar regions, leaving the people of this Alaskan coastal marshland to live off the abundant fish, birds and mammals available in the delta between the Yukon and Kuskokwim rivers. And the 18th century Russian fur traders had left the area more or less intact, making it an especially rich place for ethnographic study back in the 1870s.

It was a fact that did not escape the Smithsonian's farseeing assistant secretary, Spencer F. Baird. When a brilliant, 22-year-old naturalist named Edward W. Nelson (1855-1934) approached him seeking employment in 1877, Baird quickly sent him off to gather weather data at an Army Signal Service weather station in the village of St. Michael, on Norton Sound. He also asked him to gather objects that would yield information about the culture of these Yupik-speaking Eskimos, whose cultural tradition turned out to be wholly distinct from that of the Inupik-speaking Eskimos to the north--one of the show's most salient points.

Starting with $250 during the first year, Nelson spent four years collecting (by barter or purchase) some 10,000 objects--so many, in fact, that he became something of a local joke among the Eskimos, who called him "the man who buys good-for-nothing things." That good-for-nothing collection--now priceless--provided the lode from which this exhibition was selected by Smithsonian curator William W. Fitzhugh and his assistant, Susan Kaplan. The exhibition came about with the help of interest and prodding from Sen. Ted Stevens (R-Alaska) and his late wife Ann.

The show sets out to recreate the world Nelson found when he went to the arctic in 1877.. Several of his marvelous early photographs of Eskimo villages, with their wood and sod houses (they lived above ground in summer, halfway below in winter) have been blown up to serve as backdrops in the succession of halls. The exhibition provides superb examples of the various tools (darts, harpoons, lances, braining-stones) employed in gathering food and skins, the objects used in the home (beautiful bentwood bowls made from driftwood) and ingenious parkas and boots of fur and gutskin which have never been bettered by the designers who continue to be inspired by them. Though the highly sophisticated bentwood objects come as a surprise in the context of Eskimo art, the fine baskets--made from the ample grasses of this marshy area--are even more startling in their finesse.

The women seem to have been the tanners, tailors, seamstresses and furriers; the men--who spent at least part of their time in a separate men's house--the carvers of ivory tools, amulets, delicate needle cases, thimbles and hair ornaments, as well as the decorated wooden bowls used in food service. The men also made the scary and wonderful masks that expressed the spirits or "inua" that these Eskimos believed existed in every living thing. This belief pervaded every aspect of their lives, and reference to such spirits can be seen in nearly every object in the show.

There are, for example, wooden sun visors (to prevent snow-blindness), carved in the form of ravens, referring to the creation myth in which the Raven-god first saw man and pushed his beak to the top of his head, revealing a human face. Such witty interchanges also can be seen in several toothy masks that teeter between the human and animal worlds. Some masks have hands protruding from their sides, the holes at the center symbolizing the belief that some of the animals must be allowed to escape to ensure the species' survival.

Accompanying the exhibition is an extraordinary catalogue--the first real study of the Bering Sea Eskimos--written by the show's curators, and published by the Smithsonian. Designed by Alex Castro, with excellent photographs and superb text, the book is a subsidized steal at $12.50. The exhibition, which ends with a section on contemporary Eskimo art (some of which is for sale), continues through 1982.