INTRODUCTION 
- 
offered to night workers; to consider the health factors in- 
volved in night work; to compare relative costs of operation 
between day and night work; and finally to summarize the 
experience of plants with night work with a view to itsevalua- 
tion as a force in industry. 
This report is based upon information furnished by 243 
companies, with an employment of 1,174,947. Public em- 
ployments were excluded, and emphasis was placed upon 
private manufacturing establishments. The inclusion of 
plants of varying size located in different sections of the coun- 
try and manufacturing a wide variety of products assures the 
representative character of the study. Of the 928,794 em- 
ployees in plants reporting both the number of employees 
and the number of night workers, 91,429 were reported as 
night workers.