They finally reached Lake Winnipeg and they went around the windy north shore to the mouth of the Saskatchewan River. That fall they built a post on the south fork called South Branch House. Over the winter, Thompson took up his clerical duties again since the post master couldn’t read or write.
The following summer he went out with a company of men to trade with the Blackfeet Indians. They also traded with the Piegans, and stayed with them in their camp over the entire winter. Thompson had the opportunity to hunt buffalo with the Indians. He noted how difficult life was for the Indian women and how much a simple thing like a steel needle made a difference. He noted there daily routines like the young Indians painting their faces and admiring themselves. He also learned about the tradition of greeting with the left hand, whereas the right hand is that meant for throwing spears and pulling triggers, an invitation to fight.
In the summer of 1787, Philip Turnor, the company’s surveyor and astronomer arrived. Much of the land was still unmapped and surveyed. Turnor had been hired to survey the river routes and their territory. Under Turnor Thompson trained again in practical astronomy. He learned to calculate latitude and longitude.
He showed a real knack for the work. He spent a good deal of time charting the latitudes and longitudes from Cumberland House to York House. His apprenticeship expired in 1791, but the company gave him a three year contract for surveying work. The next five years were spent surveying Hudson Bay, Lake Winnipeg, and other points in Alberta. He also helped establish several trading posts.
