ionising men's views of the inhabited globe. He first showed
his mettle in the capture of Ceuta, opposite Gibraltar, at the
time of the battle of Agincourt, 1415, and by this means he first
planted the Portuguese banner on the Moorish coast. This contact
with the Moors may possibly have first suggested to Prince Henry
the idea of planting similar factory-fortresses among the Mussulmans
of India; but, whatever the cause, he began, from about the year
1418, to devote all his thoughts and attention to the possibility
of reaching India otherwise than through the known routes, and
for that purpose established himself on the rocky promontory of
Sagres, almost the most western spot on the continent of Europe.

Here he established an observatory, and a seminary for the training of
theoretical and practical navigators. He summoned thither astronomers
and cartographers and skilled seamen, while he caused stouter and
larger vessels to be built for the express purpose of exploration.
He perfected the astrolabe (the clumsy predecessor of the modern
sextant) by which the latitude could be with some accuracy determined;
and he equipped all his ships with the compass, by which their
steering was entirely determined. He brought from Majorca (which,
as we have seen, was the centre of practical map-making in the
fourteenth century) one Mestre Jacme, "a man very skilful in the
art of navigation, and in the making of maps and instruments."
With his aid, and doubtless that of others, he set himself to study
the problem of the possibility of a sea voyage to India round the
coast of Africa.

[Illustration: PROGRESS OF PORTUGUESE DISCOVERY]

We have seen that Ptolemy, with true scientific caution, had left
undefined the extent of Africa to the south; but Eratosthenes and
many of the Roman geographers, even after Ptolemy, were not content
with this agnosticism, but boldly assumed that the coast of Africa
made a semicircular sweep from the right horn of Africa, just south
of the Red Sea, with which they were acquainted, round to the
north-western shore, near what we now term Morocco. If this were
the fact, the voyage by the ocean along this sweep of shore would
be even shorter than the voyage through the Mediterranean and Red
Seas, while of course there would be no need for disembarking at
the Isthmus of Suez. The writers who thus curtailed Africa of its
true proportions assumed another continent south of it, which,
however, was in the torrid