1 The Birth of Science - MSRI

294 11. The Age-Long Recovery
ple automaton. Folio 9r shows and describes a gimbal suspension, which
has been called the first of its kind but is essentially a copy of the figure
that accompanies chapter 56 of Philo. 20 The sketchbook’s most fascinating
device may be another one found on folio 22v, whose caption reads: “How
to make an angel keep its finger pointing toward the sun”. It is based on
an escapement, according to one plausible interpretation. 21
Among technological finds that spread around Europe in the thirteenth page 363
century are lenses (about which we will say more later) and mechanical
clocks based on demultipliers 22 and escapements. Price, who was the
greatest specialist on the subject, remarked on the close analogy between
Hellenistic planetaria and a number of Chinese astronomical clocks from
between the second and the ninth centuries A.D., as well as the recurrence
of particulars found in the Antikythera machine (e.g., the shape of the gear
teeth) in Islamic clocks and European clocks of the fourteenth century. 23
The thirteenth century also saw the first astronomical tables made in
Europe: the famous Alfonsine Tables (1252), compiled in Spain by Christian,
Jewish and Muslim scholars by order of the Castilian king Alfonso X.
Soon thereafter gunpowder was introduced to western Europe. 24
Scientific knowledge gave Spain and Portugal a mighty edge that lasted
for centuries. This is mostly clearly seen in navigation. In the fourteenth
century the Spanish and Portuguese, thanks to mathematical geography
learned from the Arabs, were still the only Europeans able to draw trust-
20
[Philo/Prager], p. 216; Prager remarks on the identity on pages pp. 26–27. Priority for Villard
de Honnecourt is claimed for example in the exhibit of the Bibliothèque nationale de France on the
subject, at http://classes.bnf.fr/villard/analyse/inv/index3.htm.
21
China had mechanical clocks with escapement mechanisms at least as early as the eleventh
century.
22
Heron, describing demultiplier gears, systematically remarks that they slow down the movement
by a factor equal to the mechanical advantage.
23
[Price: SSB], chapter 2; [Price: Gears], pp. 42–43, and on p. 44: “It seems quite clear that the
tradition of the geared calendrical work must have been continued from Greco-Roman times to
Islam.” However, he does not exclude the possibility of independent reinvention of complicated
clockwork; after discussing the differential gear, which is not attested after Antikythera until the
sixteenth century, he writes: “Perhaps there is a particular sort of inventive mind that has its particular
brilliance in the perception of such things as the complex relationship of a gear system of or
an involved mechanism. . . . I think that several times in history such genius has made geared astronomical
clockwork so far ahead of his time that after him the development has rested for awhile
to emerge with a tradition augmented more by stimulus diffusion than by direct continuation of
the idea” ([Price: Gears], p. 61). But we will see in the next section (note 49) that the possibility that
the differential gear was an independent invention of the modern age can be discarded.
24
The invention of gunpowder is generally attributed to the Chinese, who had known it for
centuries by the time it was introduced to western Europe (probably from Byzantium). But perhaps
the difference was not great between gunpowder (saltpeter, sulfur and charcoal) and “Greek fire”
(saltpeter, sulfur and naphtha, which seems to be the composition stated in a ninth-century treatise:
see, for example, [Ensslin], pp. 49–50). Greek fire is usually considered to be a seventh-century
invention, but Ensslin lists a number of sources that attest its use in the fifth century A.D.
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