An Ottawa historian’s discovery of a 19th-century manuscript previously unseen by scholars has shed new light on the 1867 unearthing of “Champlain’s Astrolabe,” the navigational instrument famously — though controversially — believed to have been lost by French explorer Samuel de Champlain during his pioneering journey up the Ottawa River exactly four centuries ago this year.

The 13-centimetre-wide, 629-gram circle of brass, repatriated from a U.S. collection in 1989 for $250,000 by the Canadian Museum of Civilization, is widely considered one of country’s most important and evocative historical artifacts — though there is no direct proof it ever actually belonged to Champlain, the 17th-century founder of New France.

And Carleton University historian Bruce Elliott’s discovery of an 1893 document penned by Capt. Daniel Cowley — an Ottawa Valley steamboat entrepreneur who had been a key part of the astrolabe saga when it was found 26 years earlier — appears to strengthen the case against Champlain’s ownership of the object.

Elliott acquired Cowley’s writings at an auction of 19th-century manuscripts once owned by an early Canadian researcher and biographer, Henry Morgan. In Cowley’s handwritten reminiscences about operating the Muskrat Lake steamboat service in the Upper Ottawa Valley during the mid-1800s, he offers fresh details about the astrolabe’s discovery and early handling — including the fact that the relic was in his own possession for a time.

“It was in my desk on the steamer for some months afterwards,” Cowley notes.

Some researchers assert that the astrolabe was likely left behind by a Jesuit missionary as part of a traveller’s supply cache, a theory bolstered by the fact that the device was apparently found with a set of communion cups. Yet Elliott and most other scholars don’t rule out the possibility — however slim — that the astrolabe might have been owned by Champlain, who bypassed a rough stretch of the Ottawa River in June 1613 by portaging along a trail near present-day Cobden, Ont.

That’s where the astrolabe was found in August 1867, amid the upturned roots of a felled tree, by 14-year-old farmboy Edward Lee. At the time, he and his father were clearing bush for a road serving the Muskrat Lake steamboat service about 150 kilometres northwest of Ottawa.

Lee gave the astrolabe to Charles Overman, a steamboat pilot who worked with Cowley. When Overman later moved to a new job in Pembroke, Ont., “he took the instrument with him there,” Cowley states in his unpublished memoirs, “and (I) do not know how it was finally disposed of, or who got it.”

The artifact eventually wound up in the collection of a wealthy American antiquarian, who willed it to the New York Historical Society in the 1940s. The astrolabe was dramatically acquired by the Canadian Museum of Civilization in June 1989 on the eve of its official opening.

At the time, the new museum’s director, George MacDonald, called the astrolabe “a national icon,” and then-communications minister Marcel Masse described it as “a sacred part of our history” and “a symbol of the discovery of our land.”