The Eternal Explorer : THE AFTERLIFE OF GEORGE CARTWRIGHT, <i> By John Steffler (Henry Holt: $22.50; 293 pp.)</i>

A horseman in what looks like stage costume, a falcon clawed to his gauntleted right arm, rides along a busy highway near Nottingham. Cars, buses and trucks zoom up and pass right through him. Three nuclear cooling-towers loom palely a little way off, smog blankets the urban sprawl, but to the rider it is a golden afternoon in a pastoral landscape. The River Trent “is a long placid smile in a green face.”

The falconer has been making this ride for 170 years. He is the ghost of George Cartwright, a late 18th-Century soldier and adventurer who, for a dozen years, was among the first explorers and settlers in Labrador. The Canadian poet John Steffler has used this minor historical figure for a novel tracing the phosphorescent wake that a consuming human passion leaves on the ocean of human memory.

Cartwright, son of a genially eccentric squire and inventor, had a ragged sort of military career in India and Germany, and rose no higher than captain in the malarial backwater of Minorca. His last 35 years or so were spent in the agreeable but humdrum post of barracks-master or chief executive officer of the Nottinghamshire militia. And in between there were a dozen years of unexpected, dizzying vocation.

Visiting Newfoundland, where his brother was serving as a Naval officer, he is seized by the idea of the far north. With a fellow-explorer as partner, on credit and a government patent from London, he successively founds and loses two small fur-and-fishing enterprises in Labrador. It is more than a matter of gaining power or fortune; it is becoming the Adam of an unknown realm open for discovery, exploration and--he is a disciple of the naturalist Joseph Banks--naming.

Steffler could have told Cartwright’s story conventionally, by having him remember it in his old age. The old man did, in fact, use his barrack-master days to write a sweetened-up account of his time in Labrador and become a minor celebrity. By making him a ghost instead of a geezer, the author accomplishes much more. Death provides an active and heightened form of remembrance. The ghostly rides are a search; the ghostly falcon is its emblem. An interlude of greatness in a life--stardom, military glory or some other transfiguring enterprise--can turn the rest of the life into a perpetual, haunting question.

Periodically, then, there are glimpses of the rider interspersed among the passages of his life. Perhaps the ghost comes a little too frequently and routinely, but mostly he gives an echoing cadence, an unresolved quality more memorable than any flat narrative assertion. It is not that silences and mysteries are expressive in themselves, but they can make us listen and look more attentively; and the purpose of fiction, after all, is not to recite a story but to make the reader hear it.

Cartwright’s father squandered his fortune building half a bridge over the Trent--his funds ran out--and trying to develop a thistle without prickles as a cheap and universal food. His brothers are idealists as well. The Navy man quits to become a social reformer, another is a clergyman-inventor. Cartwright himself is turbulent and unsettled; the Army seems a way out.

India is mostly tedious expeditions to collect taxes for the East India Co. Steffler makes the tedium memorable; here he describes one futile march: “The road out of Madras was a sleeping creature that woke up and joined the column. It rose and attached itself to faces and clothes, wagons and animals, coloring everything like the land itself a burnt rusty beige.” The futile campaign against the French on the flatlands of Prussia is described as freezing fog and a stench of “smoke . . . mud, horse, decaying meat.” Bankers follow the army; the officers must borrow to replace their mounts and keep a supply of elegant uniforms.

After this, Labrador was like an amphibian’s metamorphosis from breathing water to breathing air. Men are not dwarfed by the wilderness, Cartwright finds, but expanded. “Each was a town, a country himself.” He builds a wooden compound that keeps catching fire, and organizes a flourishing network of trappers, fishermen and furriers.

One part of him is the businessman and maintainer of the British heritage. When one of his men is caught having sex with a dog, Cartwright has him sent to Newfoundland to be hanged. Mrs. Selby, an English bluestocking who has come to Labrador as his lover and housekeeper, remonstrates. The law must be maintained, Cartwright insists, or the wilderness will take over. “Law must be different. . . . I say we have nothing to fear but what we bring with us,” Mrs. Selby insists. She is a splendid character; at one point she rewrites his journal because it fails to recognize her properly.

But Cartwright has a restlessness beyond his role. He leaves the compound for days on end to wander and explore and gather specimens. He becomes close friends with an Inuit leader, Attuiock, and the lover of Caubvick, one of the married women in the clan. When he returns to England to sell his furs, he takes the Inuit with him. As explorers in England they are as lordly as the English are in Labrador, and more subtle. There is a comically satirical scene in which George III makes a fool of himself patronizing them.

Smallpox, contracted in England, kills them all. It is one of Steffler’s poetic reticences that he does not show Cartwright grieving; instead, we see him setting up a new compound farther north. There is new prosperity until American privateers seize his stock, ruining him and sending him back to England to live out the prosaic 35-year aftermath of a 12-year vision.

Once, exploring, he had come upon a stream in which dozens of polar bears were cavorting. Those white behemoths at play were a dazzling, an unearthly sight. Cartwright could only respond with his gun, killing half a dozen. The memory would stay with him until the moment of his death. His falconer ghost relives that moment daily. The dying man imagines a white bear approaching and beginning to devour him.

“He watches and, incredibly, feels no pain, feels instead the satisfaction of feeding a fierce hunger. He has been starving for so long. And with each bite, as more of him vanishes, a feast of new beauty appears. Small ferns and mosses curly as hair spring from the cracks in the rocks where he was sitting. . . . The bear’s white head is a wide pointed brush, moving from side to side, painting him out, painting the river, the glittering trees in.”

Writing of Cartwright and his ghost, Steffler leads us along a bewitching borderline. On one side there is the sanguine man of action and conquest, drawn in deft and unexpected strokes. On the other, there is the longing of this assertive figure to disappear into a larger and more radiant universe.