In the beautiful late summer of 1874, it fell to Assistant Astronomer Captain James Gregory of the U.S. Army Corps of Engineers to draw the last few miles of the Medicine Line. Behind him stretched a string of earthen mounds and wooden posts, running in a graceful arc across nearly 800 miles of high plains desolation back to the Canadian Shield and the swamps of Lake-of-the-Woods. A few miles ahead and more than 3,000 feet above him, perched on a rocky saddle along the very spine of the continent, stood a stone cairn erected thirteen years earlier at the terminus of the International Boundary Survey that had brought the 49th Parallel east from the Pacific coast. Gregory's last observations would be the final piece in the century-long process of defining the boundary between the United States and Canada from the Atlantic to the Pacific.
Since beginning their second summer season just west of Wood Mountain (about half-way across modern-day Saskatchewan), the American and British-Canadian parties had leapfrogged each other across the high plains. Working mostly independently but meeting regularly to socialize and to confirm each others' results, the teams had surveyed and marked nearly 300 miles of the line in only two months.
By mid-August, working at breakneck speed to avoid the prospect of a third season in the field, the advance parties had crossed the Belly River and climbed into the Rocky Mountains. After two months of short rations, foul, alkaline water and relentless, shimmering heat (the surveyor's worst enemy), they found themselves in what they could only describe as paradise. Amid the sublime peaks and valleys of the eastern slope, the soldiers' cool, professional detachment broke down and glowing accounts of rich grass, crystal clear water and huge trout appear alongside the charts, chronometer checks, and stellar observations that are the usual stuff of their official reports.
Following the pattern of establishing alternating astronomical stations, the British had set up shop on the banks of the Belly River and it fell to the Americans to establish the fortieth (and last) station midway between the Belly and the Divide on the shore of the Waterton Lakes. No doubt brimming with confidence and anticipation, Captain Gregory led his party into the mountains. As he describes it in his final report:
Hemmed in on all sides by ranges of towering, precipitous mountains, whose peaks rise from two thousand to six thousand four hundred feet above it, the lake is unapproachable by any route save by the valley of its outlet, the Waterton River.
By turning northward, therefore, from a point on the boundary-line about twenty miles east of the lake, we headed off the outlying mountain-range, and following up the valley of the Waterton River, reached the foot of the lake, with our wagons, on the 18th of August. Camp was pitched the same evening on a fine shingle-beach at the foot of the lake, a position which, besides the practical desideratum of proximity to an abundant supply of pure, cold water, afforded us also a comprehensive view of the lake and mountain scenery, which, for picturesque beauty and grandeur, is probably not excelled, if equalled, by any on the continent.
With the exception of American Chief Commissioner Archibald Campbell and British Chief Astronomer Samuel Anderson, both of whom had been members of the Pacific Boundary Commission, none of the officers and men of the two parties had ever set eyes on the Northern Rockies. Born in Troy, New York, in 1845, the son of a Dutch Reformed Church minister, Gregory had graduated from West Point in the class of 1865 and, until being assigned to the Boundary Commission, had spent most of his career with the geodetic survey of the Great Lakes.
This was his first trip west and he had relished every minute of it.
As his men relaxed in the warm, late summer sun and his worn-out livestock began to fatten on the rich grass, Gregory was confronted with a problem he could not have anticipated. …