PREFACE

vii

turing industries where it has been applied. The study is
confined to a presentation of factual data, with no attempt to
enter upon a discussion of the general economic or social
aspects of the question, which at this stage can be matters
only of opinion and conjecture.
While this investigation was carried on, the National Industrial
 Conference Board had the benefit of the cooperation and
suggestions of its Advisory Committee on Industrial Relations,
 composed of men of special knowledge and broad experience
 in this field, to whom the Conference Board wishes
to express its indebtedness.
In the preparation of its studies, the National Industrial
Conference Board avails itself of the experience and judgment
 of the business executives who compose its membership,
and of recognized authorities in special fields, in addition to
the scientific knowledge and equipment of its Research Staff.
The publications thus finally represent the result of scientific
investigation and broad business experience, and the conclusions
 expressed therein are those of the Conference Board
as a body.
This volume is the result of an investigation conducted by
the Conference Board’s Research Staff, under the supervision
of the Staff Economic Council.

MacNnus W. ALEXANDER
President

New York City
September, 1929