NATIONAL ACADEMY PRESS
2010 Constitution Avenue, N.W. Washington, DC 20418

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 competencies and with regard for appropriate balance.

This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.

This is a report of work supported by the National Oceanic and Atmospheric Administration, the National Science Foundation, the Environmental Protection Agency, the U.S. Geological Survey, and the Department of Energy.

Cover art was provided by Eileen Kiliman, a native of White Plains, New York, now living in Front Royal, Virginia. She earned a B.B.A. in marketing and a certificate in commercial art from Pace University. After eight years of representing a graphics design firm, she has made her lifetime love of art a full-time profession, receiving a variety of commissions. Her style projects childhood observations combined with adult introspection.

Library of Congress Catalog No. 94-74048

International Standard Book Number 0-309-05096-0

Additional copies of this report are available from:
National Academy Press
2101 Constitution Ave., NW Box 285 Washington, DC 20055 800-624-6242 202-334-3313 (in the Washington Metropolitan Area)

B-512

Copyright © 1994 by the National Academy of Sciences. All rights reserved.

Printed in the United States of America

First Printing, January 1995

Second Printing, August 1996

Third Printing, December 1996



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement