health, but he still could not use his leg.
As the darkness of winter came again, David began to face his bleak future. With a bad leg, his only option was the dreary duty of a trading post clerk. He missed old Saukamappee, and he longed to ride back to the open plains and the Bow River and to feel again the prairie wind.
6
Cumberland House
The sun had left the sky for many hours when David limped onto the frozen surface of Pine Island Lake. The ice-crusted hem of his buffalo robe dragged in the snow, leaving a track of brush-marked footprints that led far out from the dim lights of Cumberland House. He wanted to see all of the night sky. He cast the heavy robe fur-up onto the snow and lay upon it, gazing skyward. The stars in the immense blackness captivated him. Some were just faint imaginings, more like speculations than stars. Others, like beacons from a nearby shore, were brilliant and dazzling in the heavens. These were his signposts, especially Polaris, the gleaming North Star, and the two guiding constellations of Cassiopeia and Ursa Major, which flank Polaris east and west. “These stars will tell you latitude,” Philip Turnor had explained with enthusiasm early that morning.
David Thompson Taking an Observation. His trail by stars. Using a sextant, compass, and the stars in the sky, David Thompson mapped Canada’s vast wilderness.
David could hardly believe his turn of fortune. He had been a trading clerk for only two months and Tomison’s brigade had just recently departed when two canoes arrived unexpectedly at the post. Among the arrivals was Philip Turnor, the famed HBC surveyor and prominent man of science. He had helped compile the Nautical Almanac used by mariners around the globe for celestial navigation. Part of Turnor’s assignment in Rupert’s Land was to map the route to Lake Athabasca, but he was also to train a select few Hudson’s Bay men as company surveyors. These new surveyors were to meet the growing need for maps of the ever-expanding trade routes. If his leg continued to improve, David could be one of them.
“One of the greatest scientific advancements of our time is being able to describe where we are on the earth’s surface. James Cook’s voyages are celebrated not so much because of where he went, but because he was able to chart his voyage in latitude and longitude with exceeding accuracy. His charts help Britain dominate the world’s oceans,” explained Turnor, as the middle-aged scientist and David warmed themselves by the afternoon fire.
“If we wanted to send someone to Montreal, it would not be difficult because people know where Montreal is. It’s up the St. Lawrence River, one thousand and seventy-four miles from the river’s mouth. Or, it’s a two-day paddle east of the last portage on a well-travelled trade route. Closer to town, they could follow signs and roads. But what if, like us now, one sits on the edge of a vast wilderness with no roads, signposts, or maps? We can follow the rivers, which is what you and I have mostly done, or we could hire an Indian guide to take us to the next big water. But how do we tell the world how to retrace our steps? Well, we look to the stars.”
David knew all this, but somehow, with Turnor, it was like hearing it for the first time, and it filled him with a hunger to know more.
“The moon travels across the sky like the steady hand of a clock,” continued Turnor. “It moves approximately its own width every hour. Behind the moon like numbers on the clock’s face, are the stars. When the moon passes a known star, the time is told.”
The Astronomer Royal, Sir Nevil Maskelyne, had worked tirelessly at the Royal Observatory in Greenwich compiling tables that predicted the path of the moon and other heavenly bodies. Turnor had assisted him, as both scientists painstakingly tabulated the exact time at Greenwich when the moon passed certain stars. The tables were updated every year with new and more complete information and published as the Nautical Almanac. Earlier that day, Turnor had handed David his own first copy.
As David lay in the snow, he observed the moon on its journey, and he knew he would learn to calculate the time at Greenwich by referencing Maskelyne and Turnor’s tables. He could find the exact local time by resetting his watch each day by the noon sun. The difference in time between zero longitude at Greenwich, England, and where he lay in the snow, would determine the longitude of Cumberland House. This is because the earth also turns like clockwork, as it rotates around its axis fifteen degrees of longitude for every hour.
It wasn’t quite that simple, of course. He thanked his old teacher Thomas Adams for drilling enough trigonometry into him so he could struggle through hours of exacting calculations. Performing the mathematical corrections for refraction and parallax that Turnor demanded was tedious work, but it was worth it. Surveying would be his escape from the company store, especially since his leg was getting stronger each day.
“Latitude is less problematic,” Turnor told him, “because there is a relatively painless method,” the astronomer added quickly, as his new student paled at the prospect of more calculations. “Latitude can be found by simply measuring the angle of Polaris above the horizon. The North Star is always over the North Pole no matter where in the world it is viewed from. The earth spins and swings like a ball on string suspended from Polaris and is therefore constant among the rush of stars travelling from east to west across the night sky. At dusk or dawn, when the horizon can still be seen in the dim light and Polaris is visible in the murk of the transitional sky, the angle read on the sextant is almost equal to the latitude on which the observer is standing. Some corrections have to be applied to get the exact latitude, but a very convenient method nonetheless.”
The next morning, David and the men of the post heaved the last few shovels of frozen earth onto the fresh mound that covered Mr. Hudson’s shallow grave behind the storehouse. Hudson, Turnor’s assistant, had been sick when their canoes arrived, and he had grown progressively weaker until finally the unknown ailment took the assistant’s life. That evening, David returned to his quarters and began practising refraction calculations, partly to forget about Hudson’s death. The grave could have easily been his own just a few months earlier. But he also studied to ready himself. Turnor would need a new assistant.
Accidental? David wondered. A circumstance of birth sent me to Grey Coat where it was predetermined that I study mathematics and navigation. An unavoidable injury suffered in the wilderness fated me to study under a famous astronomer. Now Hudson’s death means Mr. Turnor needs an assistant. Maybe I was never supposed to navigate a ship but was meant to be a map-maker and chart unexplored lands.
The prospect of being able to help map the vast unknown like the famous Captain Cook kept David studying under a flickering candle late into the winter nights. By winter’s end David’s eyes were inflamed from working under dim light. Still, he drove himself until Turnor made ready to leave Cumberland House for his mapping expedition. By that time David was near blindness, weakened by an infection, and unfit to go. He was forced to stay behind while Peter Fiddler, another young clerk, took his place at Turnor’s side.
Before Turnor left, he called David aside. “So, young man,” he said, “Do me a favour. Don’t try so hard next time. They tell me you’re being sent back to York Factory as soon as your eyesight recovers. Your leg has healed nicely so I’ve sent a letter to the factor recommending you as a surveyor. Keep faith that your time will come. And use this,” said Turnor, handing David a brass sextant. “The radius is small but it was made by Peter Dolland, one of the finest makers in England. You can use it ’til we meet at York Factory next year. All the best, Mr. Thompson,” the astronomer said, handing David the sextant’s storage box.
Turnor’s party shoved off, leaving David standing at the lake’s rocky shore with his dreams held in that small wooden box. One day, he hoped, the Company might ask him to cross the mountain range to the west. Then, when one of the creek beds he’d been following for days dwindled to nothing and it was