VARIABILITY OF RATE OF CULTURAL CHANGE 367
The lateen sail had been invented in the Indian Ocean; and lateen
caravels had been introduced into the Mediterranean by the Muslims
and had been borrowed by the Portuguese from them.1 In Prince Henry
the Navigator's annual southward voyages of discovery down the Atlantic
coast of Africa, which had begun in A.D. 1421, if not before,2 caravels
were 'first used in 1440, to judge by Azurara'.3 The virtue of the lateen
rig was that it enabled the navigator to beat to windward;4 but in this
rig there were two drawbacks to set against the advantage. One was that
in a lateen-rigged vessel it was difficult to 'go about*—a manoeuvre that
might be seldom necessary in monsoon navigation, but that became a
matter of serious concern when the lateen rig was introduced from the
Indian Ocean into other waters.5 The other drawback of the lateen rig
was that the size and weight of lateen spars were so great in proportion
to the size of the sail which they could carry, by comparison with the
sail-carrying capacity of the square rig, that this defect of the lateen rig
set limits to the maximum spread of canvas, and therefore to the maxi-
mum size of the vessel thus equipped.6

Out of these two piquantly diverse types of vessel, the Portuguese and
Spanish shipwrights succeeded, before the end of the fifteenth century,
in creating a new composite type with a mixed rig, the caravela redonda.7
This was a three-masted vessel of barquentine rig, in the sense that it
carried square sails on the fore-mast and lateen (not, of course, yet fore-
and-aft) sails on the main-mast and the mizen-mast.8 By an early date in
the sixteenth century this type—with the main-mast as well as the fore-
mast now square-rigged—had become the standard type throughout
Western Christendom ;9 and, though the vessels used by Vasco da Gama
are recorded to have been, not caravelas redondas, but naus,10 we may
presume that these late-fifteenth-century 'ships1 resembled the late-
fifteenth-century caravels in having a mixed rig, even if they differed
from them in being of heavier tonnage11 and clumsier build. In the course
of the sixteenth century this clumsiness was fined down in the build
of the galleon, which was a carrack with a caravela redonda's mixed rig
and with a Mediterranean galley's slim lines.13 By A.D. 1485 the navi-
gators of this full-blown Modern Western *ship* had equipped them-
selves for finding their way over the high seas by mastering the art
-1—invented by Arab navigators in the Indian Ocean—of reckoning their
latitude by the co-ordinated use of the quadrant and a set of astronomical
tables.13 By the opening of the sixteenth century they had equipped them-

0*00 Descobri-

mento e (Jonguista de Gruznl, edited, by Uarreira and aantarem \raris 141, Aillaud)*
English translation by Beazley, C. R., and Prestage, E.: The Chronicle of the Discovery
ana Conquest of Guinea (London 1896—9, Hakluyt Society, 2 vols.).
* See Parry, op. cit., p. 23.

s See ibid., p, 23. 6 See ibid., p. 23.

See Prestage, op. cit., p. 332, Parry, op, cit., p. 24.
See Bowen, op. cit., p. 9; Parry, op. cit., pp. 24-25.

See Parry, op. cit., p. 25. I0 See Prestage, op. cit., p. 333.

11 According to Prestage, op. cit., p. 332, the tonnage of the Ocean-faring caravelas
redondas ranged from 150 to 200 tons, as against a range of from 400 tons to 800/1,000
tons for Vasco da Gama's naus.

z See Bowen, op. cit., p. 7. I3 See Prestage, op. cit., pp. 315—18.