First published in 1976
This edition 1977

This book is copyright under the Berne Convention. All rights are reserved. Apart from any fair dealing for the purpose of private study, research, criticism or review, as permitted under the Copyright Act, 1956, no part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, electrical, chemical, mechanical, optical, photocopying, recording or otherwise, without the prior permission of the copyright owner. Enquiries should be addressed to the publishers.

© George Allen & Unwin (Publishers) Ltd. 1976

ISBN 0 04 330276 9

Printed in Great Britain
in 10 point Times Roman type
by Unwin Brothers Limited
The Gresham Press
Old Woking, Surrey