Copyright, 1940, by 

 PRENTICE-HALL, INC. 



70 Fifth Avenue, New York 



ALL BIGHTS RESERVED. NO PART OF THIS BOOK MAY BE 



REPRODUCED IN ANY FORM, BY MIMEOGRAPH OR ANY 



OTHER MEANS, WITHOUT PERMISSION IN WRITING FROM 



THE PUBLISHERS. 



First Printing October, 1940 



Second Printing October, 1946 



PRINTED IN THE UNITED STATKB OF AMBRICA 



