92 Mackenzie’s Voyages

wilds. “Turner found Fort Chipewyan to be 115° west
longitude, thus placing Lake Athabasca more than three
hundred leagues from the Pacific, instead of the meagre
fifty leagues guessed at by the optimistic Pond, all of whose
maps were remarkably foreshortened on the Pacific and
Arctic sides,

In the same letter to Lord Dorchester, Mackenzie says:
““Not having been furnished with proper instruments to
ascertain the longitude in my first expedition, I made myself
but little known during my residence in London, the
winter of 1791-2, but, to prevent the like inconveniency,
I then purchased proper ones in case I should make a
second attempt.”

There is no information about his stay in London beyond
what he himself furnishes. But his subsequent observations
indicate a more accurate method, although, as in the case of
all navigators of the time, there were minor discrepancies.?

It seems proper at this point to give a résumé of the
information regarding the Pacific Coast which was avail-
able in London when Mackenzie was there, and to which
he must have had access. he summary must of necessity
begin with the advent of the Spanish in America, and follow
in brief outline their advance from the south, the encroach-
ments of the Russians in the north, the intrusions of the
British and American fur-traders in the intervening waters,
and the clearing up of the complicated situation by the
Oregon Treaty in 1846.

Within half a century of the re-discovery of America
by Columbus, the rich and populous country of Mexico
was wholly in the power of Spain. The larger islands of the

1 With the best instruments of the day there was a difference of
between fifteen and sixteen miles in the position of Nootka as
observed by Cook and Vancouver.