movable rings which may have served to carry
movable scales on one of the three dials. The third fragment (fig. 7,
top) has a pair of rings carefully engraved and graduated in degrees of
the zodiac (this is, incidentally, the oldest engraved scale known, and
micrometric measurements on photographs have indicated a maximum
inaccuracy of about 1/2 deg. in the 45 deg. present).

[Illustration: Figure 7.--ANTIKYTHERA MACHINE, TWO SMALLER FRAGMENTS.
(_Photo courtesy of National Museum, Athens._)]

Unfortunately, the very difficult task of cleaning the fragments is
slow, and no publication has yet given sufficient detail for an adequate
explanation of this object. One can only say that although the problems
of restoration and mechanical analysis are peculiarly great, this must
stand as the most important scientific artifact preserved from
antiquity.

Some technical details can be gleaned however. The shape of the gear
teeth appears to be almost exactly equilateral triangles in all cases
(fig. 8), and square shanks may be seen at the centers of some of the
wheels. No wheel is quite complete enough for a count of gear teeth, but
a provisional reconstruction by Theophanidis (fig. 9) has shown that the
appearances are consistent with the theory that the purpose of the
gears was to provide the correct angular ratios to move the sun and
planets at their appropriate relative speeds.

[Illustration: Figure 8.--ANTIKYTHERA MACHINE, DETAIL FROM FIGURE 6,
showing gearing. (_Photo courtesy of National Museum, Athens._)]

Thus, if the evidence of the Antikythera machine is to be taken at its
face value, we have, already in classical times, the use of astronomical
devices as complicated as any clock. In any case, the material supplied
by the works ascribed to Archimedes, Hero, and Vitruvius, and the more
certain evidence of the anaphoric clocks is sufficient to show that
there was a strong classical tradition of such machines, a tradition
that inspired, even if it did not directly influence, later developments
in Islam and Europe on the one side, and, just possibly, China on the
other.

_Note added in proof_:

Since the above lines were written, I have been privileged
to make a full examination of the fragments in the
National Museum in Athens. As a result we can read much
more inscription and make out many more details of the
mechanism. The cleaning and disentangling of the fragments
by the museum staff has proceed