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NOTICE: The project that is the subject of this report was
approved by the Governing Board of the National Research Council,
whose members are drawn from the councils of the National Academy
of Sciences, the National Academy of Engineering, and the Institute
of Medicine. The members of the committee responsible for the
report were chosen for their special competences and with regard
for appropriate balance.
Support for this project was provided by the Army Research
Office, National Aeronautics and Space Administration, National
Oceanic and Atmospheric Administration, National Science Foundation
(under Grant No. EAR-9814582), National Weather Service, and U.S.
Geological Survey. Any opinions, findings, and conclusions or
recommendations expressed in this material are those of the authors
and do not necessarily reflect the views of the sponsors.
International Standard Book Number 0-309-06648-4
Additional copies of this report are available from:
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Cover by Van Nguyen, National Academy Press. Adapted from
painting Niagara Falls by Frederick Church, 1857.
Copyright 1999 by the National Academy of Sciences. All rights
Printed in the United States of America