all comes the Venetian map of Marino Sanuto, drawn about 1306,
and putting into map-form the ideas that inspired the first Italian
voyages in the Atlantic. On this the south of Africa is washed by the
sea as the Vivaldi had hoped to find it, but the old story of a central
zone "uninhabitable from the heat" still finds a place, helping to keep
up the notion of the Tropical Seas, "always kept boiling by the sun,"
that held its own so long. Besides this, in Sanuto's map there is no
evidence that anyone had really been coasting Africa; Henry is not
anticipated and can hardly have been much helped by this very
hypothetical leap in the dark.

But the Florentine map of 1351, called the Laurentian Portolano, is to
all appearance a record of the actual discoveries of 1341 and 1346, and
a wonderful triumph of guess-work if it is nothing better. For Africa is
not only made an island, but the main outline of its coast is fairly
drawn; in its western corner the headlands, bays, and rivers are laid
down as far as Bojador, and the three groups of Atlantic islands,
Azores, Canaries, and Madeira, appear together for the first time.
Beyond this names grow scarce, and on the great indent of the Gulf of
Guinea, enormously exaggerated as it is, there is nothing to show for
certain any past discovery, which suggests that this map was made for
two purposes. First, to record the results of recent travel; secondly,
and chiefly, to put forward geographical theories based upon tradition
and inference, what men of old had told and what men of the present
could fancy.

Long after the Italian leadership in exploration had passed westward,
Italian science kept control of geographical theory; the Venetian maps
of the brothers Pizzigani in 1367, and of the Camaldolese convent at
Murano in 1380 and 1459, and the work of Andrea Bianco in 1436 and 1448,
are the most important of mediaeval charts, after the Laurentian, and
along with these must be reckoned that mentioned above as given in
1425-8 to Henry's brother, Don Pedro, on his visit to Venice. This
treasure has disappeared, but it was said by men of Henry's day and
aftertime, who saw it in the monastery of Alcobaca, to show "as much or
more discovered in time past than now." If their account is even an
approach to the truth, it was in itself proof sufficient of the
supremacy and almost monopoly of Italians in geographical theory.

With 1375 and the Catalan map of that year, which specially refers