VARIABILITY OF RATE OF CULTURAL CHANGE   369
lively effort to improve ship-design, nor any of that competitive enter-
prise that marked the race of the factory-owners for business.*1
Thus, at a date some four hundred years after the opening of the half-
century, bestriding the transition from a Medieval to an Early Modern
Age, that had witnessed a revolution in the build and rig of Western
ships, it might have looked in retrospect as if a fifteenth-century burst
of acceleration in the tempo of Western marine technology, which had
given the West a subsequent Ocean-wide ascendancy, had been a unique
bout of creativity in the long annals of a Western maritime practice that
had been almost as stagnant during the Modern sequel to this short-
lived golden age as it had been during the Medieval prelude to it. Yet
at this very date the Western art of shipbuilding was actually on the
eve of another burst of acceleration that was to produce as great a
revolution as its predecessor; and this time the work of creation at high
speed was to go forward along two parallel lines. On the one hand,
artificially generated mechanical power was to be substituted for wind-
power as the driving force by which ships were to be propelled; and
contemporaneously, in response to the same challenge that had thus
evoked the application of steam-power to navigation, the art of building
the classic Modern Western sailing-ship was to awake from, its long
slumber in order to carry an old type to a new and previously undreamed-
of degree of perfection at which, for some of the purposes of maritime
traffic, the sailing-ship was to hold its own against the steamship
throughout the doubly creative half-century ajd. 1840-90.
The new-fangled type of vessel that was to acquire its classic form in
the course of the half-century beginning in a.d. 1840 had by that year
only just emerged from the pioneer experimental stage of its develop-
ment. Though William Symington's steamship Charlotte Dundas had
plied on the Forth and the Clyde as early as a.d. 1802,* and the Atlantic
had been crossed by steam-power reinforced with sail-power in ajd.
i8i93 and by unaided steam-power hi a.d. 1827,* the era of mechanical
navigation as 'a practical proposition* did not open earlier than the
triennium a.d. 1838-40, which saw the launching of the first screw-
propelled vessel, the Archimedes,5 in a.d. 1838, the successive establish-
ment of the Cunard, the Royal Mail, and the Peninsular and Oriental
steamship navigation lines (the first two of the three hi a.d. 1839 and the
third in a.d. 1840),* and the crossing of the Atlantic under steam in
a.d. 1838 by the Siriits and the Great Western, and in aj>. 1840 by a
Britannia that was the first Cunarder to make the passage.7
'The power-ship opens a new era in water-transport* She is not evolu-
tionary but revolutionary, for she represents a complete break with tradi-
tion. Any compromise with the sailing-ship works to her disadvantage both
in efficiency and aesthetically. .. . Not till conservative tradition had been
scrapped could the power-ship evolve in accordance with her own needs.
For the power-ship is modern, different, and original. Her life is not in the
*	Bassett-Lowke, J. W., and Holland, G.: Ships and Men (London 1946, Harrap),
pp. 124-6.
I IS Sid.'; #$?•*•	* S« ibid., p. X78.	• S« ibid., p. ,7*.
*	See ibid,, p. 178.	7 See ibid., pp. 174 **& *7<>.