Underground Rivers - University of New Mexico

Chapter 3 -- Roman Encyclopedists
In order to know how much water the spring supplies it does not suffice to find the area of the
cross section of the flow which in this case is 12 square digits. It is necessary also to find the
speed of the flow, for the swifter the flow, the more water the spring supplies, and the slower,
the less. One should therefore dig a reservoir under the stream and note with the help of a
sundial how much water flows into the reservoir in a given time.
In the field of hydraulics, however, Heron’s
acknowledgement of velocity fell by the
intellectual wayside.
Reconstruction of one of Heron's “automata” by
Giovanni Battista Aleoti (1589). When
Hercules hits the head of the dragon, the
monster shoots water on his face.
In the chronologic midst of the Encyclopedists, we find Philo (20 BC - 50 AD), a Hellenistic Jew
working to harmonize his faith with Greek thought. Paradise may be located, according to Philo,
In some distant place far from our inhabited world, and has a river flowing under the earth,
which waters many great veins so that these rising send water to other recipient veins, and so
become diffused.
Philo's fellow Hebrews would have little cared about the location of Paradise and his effort added
nothing to the Roman cartographic database, but Philo's speculation illustrates the ongoing
amalgamation of philosophies. As we will see in Chapter 4, The Cross, the Christians to follow
would become adamant proponents of the "river flowing under the earth."
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