shortly afterwards in medieval Europe. At each occurrence, as here,
there are echoes of other cultures. In addition to those already
mentioned we find the otherwise mysterious "peacock, man and monkey,"
cited as parts of the jackwork of astronomical clocks of Islam,
associated with the weight drive so essential to the later horology in
Europe.

We have already seen that in classical times there were already two
different types of protoclocks; one, which may be termed
"nonmathematical," designed only to give a visual aid in the conception
of the cosmos, the other, which may be termed "mathematical" in which
stereographic projection or gearing was employed to make the device a
quantitative rather than qualitative representation. These two lines
occur again in the Islamic culture area.

Nonmathematical protoclocks which are scarcely removed from the
classical forms appear continuously through the Byzantine era and in
Islam as soon as it recovered from the first shocks of its formation.
Procopius (died _ca._ 535) describes a monumental water clock which was
erected in Gaza _ca._ 500.[17] It contained impressive jackwork, such as
a Medusa head which rolled its eyes every hour on the hour, exhibiting
the time through lighted apertures and showing mythological
interpretations of the cosmos. All these effects were produced by
Heronic techniques, using hydraulic power and puppets moved by strings,
rather than with gearing.

Again in 807 a similarly marvelous exhibition clock made of bronze was
sent by Harun-al-Rashid to the Emperor Charlemagne; it seems to have
been of the same type, with automata and hydraulic works. For the
succeeding few centuries, Islam was in its Golden Age of development of
technical astronomy (_ca._ 950-1150) and attention may have been
concentrated on the more mathematical protoclocks. Towards the end of
the 12th century, however, there was a revival of the old tradition,
mainly at the court of the Emperor Saladin (1146-1173) when a great
automaton water clock, more magnificent than any hitherto, was erected
in Damascus. It was rebuilt, after 1168, by Mu[h.]ammad b. 'Al[=i] b.
Rustum, and repaired and improved by his son, Fakhr ad-d[=i]n
Ri[d.]w[=a]n b. Mu[h.]ammad,[18] who is most important as the author of
a book which describes in considerable technical detail the construction
of this and other protoclocks. Closely associated with his book one also
finds texts dealing with perpetual-motion devices,