Abstracts Fiber-Optic Feeding Frenzy

Just when you thought it was safe to go back in the water, marine biologists have charted some capricious changes in the feeding habits of sharks. In the past two years, sharks have repeatedly attacked the new 1-in. fiber-optic telephone cable off the Canary Islands. The marauding is expensive: an average cable repair is laborious and costs at least $150,000.

What is it about fiber-optic cable? Marine biologists accompanying the repair teams have tried to find out. Along the way, they have learned that sharks generally do not feed below 3,000 ft., thus making it unnecessary to protect cable below that depth. They have also discovered previously unknown species of fish. But they still do not know why the new cable is so appealing. The favored theory: sharks attack the lines after detecting faint electric fields that trigger a feeding reflex. "Who knows why they are attracted to it?" muses Gary Nelson, chief of ichthyology at the American Museum of Natural History in New York City. "Sharks aren't all that predictable."

NEW SUPERHERO AT SIGMA XI

Sir Isaac Newton was a supergenius of science who, among other things, invented calculus and deduced the laws of gravity and optics. Sir Isaac, it turns out, also made mistakes. The University of Chicago announced last week that Robert Garisto, 23, a physics major, recently discovered in one of Newton's calculations an error that had gone undetected for three centuries.

Garisto stumbled across the blunder while puzzling over some confusing numbers from Newton's 1687 masterpiece of physics, the Principia. Newton had derived a figure for the earth's mass based on his new theory that a single force -- gravity -- governed falling bodies on earth and the motion of planets around the sun. The calculation depended on the angle between two lines from the earth to the sun, but because the angle was not precisely known at the time, Newton used slightly different figures as he revised the Principia. Although he had settled on 10.5 sec., or about three-thousandths of a degree, some of his calculations were based on an earlier estimate of 11 sec. It was that inconsistency that Garisto found -- a discovery that was promptly confirmed by other physicists. The mistake has no bearing on Newton's theory, but its discovery was enough to earn Garisto, who graduated last week, a prize from the University of Chicago's chapter of Sigma Xi, the national scientific honor society.