vi ACKNOWLEDGEMENTS 
willingly of their valuable hours ; and to the Delegates and staff 
of the Oxford Press, I would here tender my grateful thanks. 
My debt to Professors F. W. Taussig and Viner will be suffi- 
ciently obvious in the text. 
I owe a special tribute to Professor D. B. Copland, whose 
interest and criticism were my greatest stimulus; to Mr. C. H. 
Wickens, Commonwealth Statistician, who was always ready 
to produce and interpret statistics; and. to Mr. Keith Isles, 
whose criticism and help in reading proofs were invaluable. 
G.L. W. 
UNIVERSITY OF MELBOURNE, 
January, 1930.