FIRST PUBLISHED IN 1966

SECOND IMPRESSION WITH CORRECTIONS 1968

This book is Copyright under the Berne Convention.
Apart from any fair dealing for the purposes of private
study, research, criticism or review, as permitted
under the Copyright Act 1956, no portion may be
reproduced by any process without written permission.
Enquiries should be addressed to the publisher

© George Allen & Unwin Ltd.., 1966

PRINTED IN GREAT BRITAIN
in 11 point Baskerville type
BY T. & A. CONSTABLE LTD
EDINBURGH