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Ancient Roman fountains, octopuses migrate backwards, enzymes make magic

Q: How did the fountains of Greece and Rome work without electric pumps to push water so high? — Paul, Hull, Maine

Citizens of Segovia, Spain still use this Roman aqueduct. [Mary Ann Sullivan, Bluffton College]

A: Simple gravity can do spectacular work. Start someplace high — say, the Alban Hills, rising southeast of Rome to 3100 feet (945 m). This elevation can generate a hefty head of pressure — 1300 psi (25 times the standard city water pressure these days).

Aqueducts carried water into cities from nearby heights. Roman engineers often ended the aqueduct with an elevated cistern to store the water at pressure. The cistern usually fed a display fountain at its base.

The Segovia aqueduct, for example, stands 93.5 feet (28.5 m) high. An elevated cistern built at the end of this aqueduct would generate 39 psi — more than enough to drive fountain water 50 feet (15 m) into the sky.

Who needs a pump?

Further Surfing:

The Physics Classroom: Potential energy

Bluffton College: Roman aqueduct

University of London: Fons from A dictionary of Greek and Roman antiquities by John Murray, London 1875

Octopuses migrate backwards

Q: Does an octopus migrate? — Hal, New York, New York

A: Yes, some octopuses migrate but not far. The creature isn’t outfitted for great distances.

These appealing creatures migrate. [NOAA]

In the summer, she lives in a hole among rocks. When she ventures outside her hole, she creeps on her arms, gripping with her arm suckers.

Swimming, she jets backwards — blowing water out her siphon, like a slow-speed rocket with her arms trailing behind.

Octopuses migrate to deeper seawaters for the winter. In early spring, they return to shallow waters. So they do migrate, a little.

"Giant Pacific octopuses tagged off the coast of Japan have been recovered more than 50 miles away," says David Scheel, marine biology professor at Alaska Pacific University.

Enzymes make magic

Q: Are enzymes alive? — Alesha, Bayonne, New Jersey

Leucine is an amino acid found as a structural element inside enzymes [©1995-2003 by Michael W. Davidson and the Florida State University, used with permission]

A: No, enzymes are not alive but we can’t live without them. These chemical magicians change one material into another, quickly, and are left unchanged themselves. A typical enzyme can convert a thousand molecules per second, indefinitely.

Enzymes, comprised of proteins, quicken all kinds of chemical reactions. Without enzymes, the reactions would happen too slowly to do essential work, such as, digest food.

Big molecules, like proteins, have an energy barrier that prevents them from breaking into smaller molecules — a good thing. Otherwise, we would disintegrate. Cells, though, frequently do need to change and, therefore, must overcome or lower the barrier.

Heat could add enough energy to defeat the barrier but the heat would kill the cell. Harmless enzymes rescue the situation by simply lowering the barrier.

For example, enzymes interact with urea (an end product of protein metabolism) and form a compound that has a low energy barrier. The compound, consequently, breaks down quickly and forms another chemical — urine, which we can then eliminate before it poisons the body.

Further Surfing:

Florida State University: The amino acid collection by Michael Davidson

(Answered Dec. 5, 2003)

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