THE QUESTION OF FATIGUE FROM THE ECONOMIC STANDPOINT. 295 



different temperatures is afforded by the alternations of day and night, 

 though in this case many other factory conditions are introduced as 

 factors, such as the difference of sun and artificial light and differences 

 in noise and room. There may also be important differences of habits 

 and skill between night and day workers. From the economic stand- 

 point, however, it is well worth while recording some researches on the 

 comparative effect of day and night — firstly on accidents, then on 

 output. 



Eef erring to the work of Dr. Walter Abelsdorf 's ' Die Unfallhau- 

 figkeit in den gewerblichen Betrieben wahrend der Nachtschicht ' 

 (Leipzig, Vogel, 1910) the Chief Factory Inspector's Report for 1910 

 says : ' It has been found in Germany that the industrial accident rate 

 (calculated in proportion to the ascertained numbers at work) is less 

 by night than by day. In explanation of this it is suggested that at 

 night there are relatively fewer untrained workers, less crowding and 

 interruption, less transport of material, and more leisurely and careful 

 work, with correspondingly reduced output. Exceptions were met 

 with, however: thus, there was a higher accident rate by night than 

 by day in the machine-making industry in the Diisseldorf and Potsdam 

 districts, and in chemical works in the former district, but not in the 

 latter. ' 



These findings are not supported, however, by the experience of a 

 large American iron- and steel-making plant published and exhibited 

 at the San Francisco Exhibition, 1915, by the U.S. Department of 

 Labour. In each department the accident-frequency rate was as 

 follows : 



Department 



Blast Furnace 



Steel Works 



Rolling Mills 



Mechanical 



Yards 



Other Departments 



For Total Plant 



It is important to bear in mind, however, as will be pointed out in 

 Section IV., that bad lighting may have a direct effect in causing 

 accidents without affecting working capacity ; so that the conflict in the 

 conclusions of students may well be attributable to differences in the 

 standard of lighting in the factories where they investigated. 



As regards the output of night and day compared, the Curtis Pub- 

 lishing Co., of Philadelphia, very kindly presented records of the hours 

 spent by a single worker on pressing ten thousand ' good impressions 

 of the Saturday Evening Post. The average hours thus spent by fifty- 

 three day men was 5'04 per man ; by forty-six night men 4'78 per man. 

 According to this, therefore, working capacity would seem slightly 

 higher at night than during the day. 



Section II. — The Tests of Fatigue. 



To measure the results of fatigue accurately the ' test ' chosen should 

 (1) vary as the fatigue varies (e.g., be a result of fatigue), and (2) vary 

 with the fatigue only {e.g., not be a result of other factors). 



