Cats' Paws and Catapults: Mechanical Worlds of Nature and People

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"Full of ideas and well-explained principles that will bring new understanding of everyday things to both scientists and non-scientists alike."—R. McNeill Alexander, Nature
Nature and humans build their devices with the same earthly materials and use them in the same air and water, pulled by the same gravity. Why, then, do their designs diverge so sharply? Humans, for instance, love right angles, while nature's angles are rarely right and usually rounded. Our technology goes around on wheels—and on rotating pulleys, gears, shafts, and cams—yet in nature only the tiny propellers of bacteria spin as true wheels. Our hinges turn because hard parts slide around each other, whereas nature's hinges (a rabbit's ear, for example) more often swing by bending flexible materials. In this marvelously surprising, witty book, Steven Vogel compares these two mechanical worlds, introduces the reader to his field of biomechanics, and explains how the nexus of physical law, size, and convenience of construction determine the designs of both people and nature. "This elegant comparison of human and biological technology will forever change the way you look at each."—Michael LaBarbera, American Scientist

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Editorial Reviews

Library Journal
Nature often comes up with simpler solutions to engineering problems than do human engineers. Does that mean that nature's technology is superior? Arguing that nature can be improved upon, Vogel's comparison of biological and human-made technologies shows how and why.
M.R. R. Montgomery
...Perfect for the lay reader, the undergraduate and any scientist with a sense of humor. -- M. R. Montgomery, New York Times Book Review
Kirkus Reviews
Has human engineering improved on nature? A biologist answers the question. Biomechanics is the discipline that explores natureþs answers to what are essentially engineering problems. Vogel (Biology/Duke Univ.; Vital Circuits, 1992) doesnþt share the widespread assumption that human engineering is doomed to crank out clumsy imitations of what nature perfected eons before our race first chipped a stone into a cutting edge. For nature, sometimes to its disadvantage, must play by the rules of evolution, via natural selection; it is also restrained by geometrical and physical constants relating to growth and change, and it enjoys far less flexibility than do most human designersþnature cannot easily "go back to the drawing board" when an existing structure won't serve its purposes. Humanity is better at making things big, while nature excels in compactness: No bird can match a jetliner for size, but 10,000 viruses could fit along the length of our tiniest machine. Vogel explains basic principles of engineering science, giving examples both from the familiar human world and from biological entities. The problems discussed include the ways a structure (a skeleton, a bridge, a tower, a wing) can be designed to resist various stresses; ways of generating power (steam engines, wind, and water mills); and ways of building up large structures from small (bricks, cells). Certain overarching verities emerge from this investigation: our preference for the right angle, where nature uses curves; our heavy dependence on the wheel, which is almost completely unknown in nature; and our favoring of sliding surfaces (metal hinges) over bending ones (sinew, muscle). Vogel isgenerally convinced that our technology surpasses nature's evolutionary trial and error, but the reader is likely to emerge with greater respect for both. His well-written overview eyes the larger questions implicit in the subject.
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Product Details

  • ISBN-13: 9780393319903
  • Publisher: Norton, W. W. & Company, Inc.
  • Publication date: 1/28/2000
  • Pages: 384
  • Sales rank: 800,636
  • Product dimensions: 5.50 (w) x 8.50 (h) x 0.85 (d)

Meet the Author

Steven Vogel is James B. Duke Professor of Biology at Duke University. He is the author of Cats' Paws and Catapults.

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Table of Contents

Preface 9
1 Noncoincident Worlds 15
2 Two Schools of Design 20
3 The Matter of Magnitude 39
4 Surfaces, Angles, and Corners 57
5 The Stiff and the Soft 82
6 Two Routes to Rigidity 106
7 Pulling versus Pushing 128
8 Engines for the Mechanical Worlds 153
9 Putting Engines to Work 177
10 About Pumps, Jets, and Ships 205
11 Making Widgets 229
12 Copying, in Retrospect 249
13 Copying, Present and Prospective 276
14 Contrasts, Convergences, and Consequences 289
Notes 313
References 343
Index 363
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