The Coordinates That Hold Us in Place : A poet tries to comprehend the losses, disappearances and tragedies that occur all too frequently in Alaska : DISAPPEARANCE: A MAP; A Meditation on Death and Loss in the High Altitudes.<i> By Sheila Nickerson (Doubleday: $22.50; 224 pp.)</i>

The North Pole--magnetic north according to Sheila Nickerson in her slender book about Alaska--moves within a 400-mile radius. Navigating the ice-studded black waters of the Arctic becomes an even more treacherous task when trusted coordinates, the longitudes and latitudes, no longer hold fast.

There’s irony here. It isn’t always the inexperienced idealists who vanish, marching off into the wilderness like Chris McCandless (the subject of “Into the Wild,” reviewed on Page 1, makes a brief appearance in this narrative). Experienced bush pilots vanish in the middle of short flights over ice fields, professional halibut fishermen are swallowed up in sudden squalls no more than 15 miles outside of port. A 72-year-old tourist named Walter B. Shaw, one of a quarter of a million people who visit Alaska each year by cruise ship, vanished right in downtown Juneau.

“Position needs always to be reassessed, the coordinates recalculated, our place on Earth defined,” Nickerson, a poet and essayist, writes. “Our stories, our memories, our celebrations and rituals, are the coordinates that hold us in place.” “Disappearance: A Map” attempts to chronicle and comprehend the multitude of losses, disappearances, tragedies that punctuate daily life in Alaska.

Three remarkable disappearances frame the story told here. Perhaps the most dramatic is the story of Sir John Franklin, who, under orders of the British Admiralty, was to complete the exploration of the Northwest Passage. In 1845, he sailed into Alaskan waters with 128 men on two ships, the Terror and the Erebus. They were last seen by a whaler on July 26, 1845. No trace of the ships or men has ever been found. There have only been rumors. His widow, Lady Jane Franklin, commissioned searches herself and in her 70s, along with a niece named Sophia Cracroft, went to Alaska to seek some shred of evidence, anything, that might reveal what happened to her lost husband and his men.

Cracroft’s journals, published by the Alaska Historical Society, reveal Lady Franklin’s “theory of disappearance”: “The record--the written message--is everything. Press on until you have every bit of evidence that is possible. Never give up. Keep the search alive. While the search lives, the missing person lives. While the search continues, hope continues. . . . If the record is substantial enough, the missing person cannot be lost, ever.”

Nickerson also tells the story of the 1972 disappearance of a small plane carrying Alaska’s only member of the House of Representatives, Nick Begich, and House Democratic leader Hale Boggs of Louisiana. The plane has never been found, although strange FBI reports about it surface now and then.

We also learn about the disappearance of Nickerson’s co-worker, Kent Roth, and his brother Jeff, whose plane vanished during a short flight on May 3, 1992. When the official search stopped, co-workers, family and friends continued to look for the Roths. The wife of pilot Jeff Roth is convinced, months after the incident, that he is alive and will be found. She is kept going by the theory of disappearance Lady Franklin put forth more than a century earlier.

“I live in fear of the cold,” Nickerson confesses. Even as her sons and husband challenge themselves constantly with mountain climbing, hikes and trips into the wilderness, Nickerson is content to watch the light and clouds on Mt. Juneau from her home nestled within the cozy confines of downtown Juneau. She closely, sadly, monitors the end of summer and the midnight sun as her garden dies with the season. “In some gardens, the foxglove stalks are now almost parallel with the ground, close to the voice of the cold. . . . I do not remember, when I was young, such dread of the coming winter. I do not remember such profound sadness at the fate of last flowers.”

Last flowers and lost souls inhabit Sheila Nickerson’s inquisitive, probing imagination. Hers is a travel book of rare delicacy and journalistic drama.