ake
suspicion of magic. "It has the power of drawing iron to it, and if a
needle be rubbed upon it and fastened to a straw so as to swim upon
water, the needle will instantly turn towards the Pole-Star. But no
master mariner could use this, nor would the sailors venture themselves
to sea under his command if he took an instrument so like one of
infernal make."

[Illustration: SKETCH-MAP OF DULCERT'S PORTOLANO OF 1339. (SEE
LIST OF MAPS)]

It was possibly after this that the share of Amalphi came in; it may
have been Flavio Gioja, or some other citizen of that earliest
commercial republic of the Middle Ages, which filled up so large a
part of the gap between two great ages of progress, who fitted the
magnet into a box, and by connecting it with the compass-card, made it
generally and easily available. This it certainly was before Prince
Henry's earliest voyages, where he takes its use for granted even by
merchant coasters, "who, beyond hugging the shore, know nothing of chart
or needle." In any case it would seem that prejudice was broken down,
and the mariner's compass taken into favour, at least by Italian seamen
and their Spanish apprentices, in the early years of the fourteenth
century, or the last years of the thirteenth, and that when the Dorias
set out for India by the ocean way in 1291, and the Lisbon fleet sailed
for the western islands in 1341, they had some sort of natural guide
with them, besides the stories of travellers and their own imaginings.
About the same time (_c._ 1350) mathematics and astronomy began to be
studied in Portugal, and two of Henry's brothers, King Edward and the
Great Regent Pedro, left a name for observations and scientific
research. Thus Pedro, in his travels through most of Christendom,
collected invaluable materials for discovery, especially an original of
Marco Polo and a map given him at Venice, "which had all the parts of
the earth described, whereby Prince Henry was much furthered."

Good maps indeed were almost as valuable to him as good instruments, and
they are far clearer landmarks of geographical knowledge. There are at
least seven famous charts (either left to us or described for us) of
the fourteenth and early fifteenth centuries, which give a pretty clear
idea of what Henry's own age and his father's thought and knew of the
world--some of which we believe to have been used by the Prince himself,
and each of which follows some advance in actual exploration.

First of