BOOK REVIEW : A Chilling Look at the King of the Arctic : WHITE BEAR; Encounters With the Master of the Arctic Ice <i> by Charles T. Feazel</i> Henry Holt : $22.50, 240 pages

“When the watchdog growls at the door, someone’s coming,” goes the conventional wisdom of the Arctic. “When it hides under the table, look out for bears!”

We are offered this ominous advice by Charles T. Feazel in “White Bear,” an intimate account of Ursus maritimus , a creature that most of us encounter only in the sterile confines of a zoo.

The book is an irresistible armchair adventure, a natural history of the Arctic, an anthropological study of its native peoples, and--above all--a fascinating collection of the lore and legend of the polar bear.

“Always, it seems, the bear is waiting,” Feazel writes. “Throughout the centuries there have been only three constants in the Arctic: the white and the cold and the bears.”

Feazel, a geologist by training and an adventurer at heart, encountered the polar bear during various expeditions in the polar region.

At an average weight of 1,000 pounds, he tells us, the polar bear is the largest predator on earth. A polar bear may stand taller than 10 feet, with a reach of 14 feet, and it can easily outrun a person through ice and snow.

And a polar bear, so cuddly in appearance, will eat almost anything, from rodents to stranded whales--even its own young:

“In mute testimony to this natural process,” Feazel writes, “tiny claws of cubs are sometimes found in polar bear droppings.”

The great beast is both a living creature and a totem of immense potency to the native dwellers of the Arctic.

“Nanook,” as the bear is known, “was clearly the most powerful element in the lives of such people,” Feazel explains. “He determined the patterns of their lives and often the circumstances of their death. Awesome and awful, he possessed a majesty innately worthy of worship.”

What impresses Feazel most, however, is the marvelously utilitarian design and function of the polar bear’s anatomy. Tooth, bone, fur and blubber have evolved into an ideal technology for survival in the Arctic.

In fact, the polar bear is so well-suited to the frigid temperatures of the polar winter that its greatest peril is heat and hunger in summertime: “A polar bear may have to live for half a year without a meal during the ice-free season,” Feazel explains, “when he can’t hunt effectively.”

The polar bear is still hunted by the native peoples of the Arctic, but--as Feazel warns--the real enemies of “Nanook” are the intrusions of the modern world into the once-pristine environment of the Arctic.

Today, the polar bear is at risk from chemicals and heavy metals in the food chain, the detritus of oil drilling (and oil spills), and even the threat of global warming.

Still, Feazel reminds us that the most urgent threat of all are poachers and pampered tourists armed with high-powered rifles: Shooting is still the most frequent cause of death among polar bears.

Feazel never strays far from hard science, and his prose is only rarely lyrical or rhapsodic. But he cannot resist the temptation to anthropomorphize the polar bear.

He repeatedly depicts “Nanook” in human-like postures: “Picture a flamboyant prizefighter, arrogant in his heavy fur coat, mugging for the camera.” He speculates that bears kill more prey than they can eat for “the sheer pleasure of the kill.”

And Feazel, an earnest and good-natured storyteller, is not above a pun. “The end of this tale,” he quips, after a top-to-bottom inventory of the polar bear’s anatomy, “is the end of the tail.”

Next: Judith Freeman reviews “Sirens” by Stephen Pett (Vintage).