THIS book represents the substance of six Christmas lec-tures delivered to a juvenile audience at the Royal Institu-tion. The lectures were designed to illustrate the morestriking features of animal locomotion without assumingprevious biological knowledge. Wherever possible, livinganimals were allowed to tell their own story, and therecan be little doubt that they succeeded where the spokenword or blackboard diagram would have failed.
Five of the lectures were concerned with relatively well-established facts. The sixth lecture was of a different type,for it enabled the audience to see research workers inaction and hear from them, at first hand, something ofthe problems which biologists are trying to solve and howthey set about their task. Dr F. S. J. Hollick and DrJ. W. S. Pringle demonstrated the methods they havedeveloped for investigating the flight of insects; Mr D. O.Sproule provided an ' artificial ' bat avoiding obstacles bysupersonic echo-sounding, and Dr H. W. Lissmanndemonstrated the electric fields which he has recentlyshown to exist round the bodies of certain fish. Thesedemonstrations are referred to at various places in thisbook but not, I fear, in such a manner as reflects thestriking impression made by them in their original form.
It is impossible to express adequate thanks to all thosewho helped in the production of these lectures. Particulargratitude is, however, due to the British Museum (NaturalHistory) for the loan of many valuable specimens; to theZoological Society for providing a unique series of livinganimals; to London Films International for the loan of the film Around the Reef and to Gaumont British Films for anumber of slow motion films of human athletes; to MessrsLines and Messrs Hamley, and the International ModelAircraft Company for the loan of mechanical models; andto Messrs Cinema Television Ltd and Messrs Dawe forelectrical equipment and Messrs Gerrard for the loan ofvarious specimens.
On the staffs of the Royal Institution and of the Zoo-logical Department, Cambridge, fell the major task ofpreparing and assembling the demonstrations. It is im-possible to thank each person individually, but threenames must be mentioned: Mr L. Walden of the RoyalInstitution and Mr K. Williamson at Cambridge who formany weeks spared neither time nor effort, and Dr H. W.Lissmann, who not only designed and set up many of theexhibits, but who persuaded so many animals to do justwhat was expected of them at just the right time, and lateron read the proofs of this book. An author's acknowledge-ments to his publishers may be somewhat formal, but inthis instance I would like to express particularly sincerethanks to Mr F. Kendon of the Cambridge UniversityPress not only for a revision of the original manuscript butfor all that he and his colleagues have done during thepublication of this book.

LIST OF PLATES 8

LIST OF FIGURES 9

PREFACE 11

1 The Machinery of Animal Movement 13

2 Swimming 37

3 Walking and Running 59

4 Jumping and Creeping 90

5 Flying Animals 114

6 Flapping Flight 133

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