use, I have extended it down to 47° of latitude. But I am only
answerable for the accuracy of such parts as I have explored myself. In
laying down the rest I had recourse to the following authorities.

The longitude of Cape Virgin Mary, which is the most essential point, as
it determines the length of the straits of Magalhaens, is deduced from
Lord Anson, who made 2° 30' difference of longitude between it and the
Strait Le Maire. Now as the latter lies in 65° 22', Cape Virgin-Mary
must lie in: 67° 52', which is the longitude I have assigned to it, and
which, I have reason to think, cannot be far from the truth.

The strait of Magalhaens, and the east coast of Patagonia, are laid down
from the observations made by the late English and French navigators.

The position of the west coast of America, from Cape Victory northward,
I have taken from the discoveries of _Sarmiento_, a Spanish navigator,
communicated to me by Mr Stuart, F.R.S.

Falkland Islands are copied from a sketch taken from Captain M'Bride,
who circumnavigated them some years ago in his majesty's ship Jason; and
their distance from the main is agreeable to the run of the Dolphin,
under the command of Commodore Byron, from Cape Virgin Mary to Port
Egmont, and from Port Egmont to Port Desire, both of which runs were
made in a few days; consequently no material errors could happen.

The S.W. coast of Terra del Fuego, with respect to inlets, islands, &c.
may be compared to the coast of Norway; for I doubt if there be an
extent of three leagues where there is not an inlet or harbour which
will receive and shelter the largest shipping. The worst is, that till
these inlets are better known, one has, as it were, to fish for