HD 
 
 NRLF 
 
EXCHANGE 
 
mniY>ersit$ of Cbicaao 
 
 THE RELATION OF FATIGUE TO 
 INDUSTRIAL ACCIDENTS 
 
 A DISSERTATION 
 
 SUBMITTED TO THE FACULTY OF THE GRADUATE OF SCHOOL ARTS 
 
 AND LITERATURE IN CANDIDACY FOR THE DEGREE 
 
 OF DOCTOR OF PHILOSOPHY 
 
 (DEPARTMENT OF SOCIOLOGY) 
 
 BY 
 EMORY S. BOGARDUS 
 
 Reprinted from 
 
 THE AMERICAN JOURNAL OF SOCIOLOGY, XVII (1911-12) 
 CHICAGO, 1912 
 
Composed and Printed By 
 
 The University of Chicago Press 
 
 Chicago, Illinois. U.S.A. 
 
I. INTRODUCTION 1 
 
 The discussion of any question relative to industrial accidents 
 remains incomplete if the influences and possible consequences of 
 fatigue are not considered. 2 The origin of the problem of fatigue 
 in industry is to be found in connection with the industrial revo- 
 lution. Before the introduction of the factory system, employer 
 and employee usually worked side by side as companions. The 
 blacksmith had a helper or two ; the farmer had his "hired hand" ; 
 the shoemaker, an apprentice. Tools were simple; accidents, 
 rare. The occupations were usually not hazardous; the existing 
 dangers, if any, were obvious. People generally worked from 
 "sun to sun/' but in a more or less leisurely fashion. 
 
 When hand-driven tools were supplanted by power-driven 
 machinery, and the home gave way to the factory as the unit of, 
 production, the long hours of labor were carried over. Monoto- \ 
 nous, speeded-up processes took the place of interesting forms 
 of work at a leisurely rate. At about the same time, work by 
 artificial light was made possible. Consequently, work-hours, 
 instead of being shortened to suit the new mechanical processes, 
 were "considerably lengthened, and in the case of child labor 
 particularly, to a cruel degree." 3 As late as 1842, for instance, 
 the working day in cotton mills (United States) was fourteen 
 hours long. When domestic industry was supplanted by the 
 factory system, not only men but women and children in large 
 numbers were subjected to the monotonous, speeded-up processes \ 
 of machine labor and for extremely long hours. Herein is to be 
 found the origin of the problem of fatigue in industry. 
 
 From such a beginning, the fatigue problem developed rapidly 
 under cover of the laissez-faire philosophy of the last century. 
 It was held by the theorists that if labor conditions became too 
 
 1 1 am indebted to Professor C. R. Henderson for suggesting this problem. 
 3 A. Imbert. 14. Intern. Kongr. f. Hyg. u. Demog., II, 634. 
 3 Adams and Sumner, Labor Problems (Macmillan, 1008), 515. 
 
 i 
 
 255768 
 
2 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 severe in one factory, the laborers would leave and flock to other 
 factories where more favorable conditions existed. But such 
 freedom of choice was not actually open to working men and 
 women, for the severe labor conditions came to prevail generally. 
 In this way, under the protection of laissez faire, the fatigue 
 problem came to assume amazing proportions. Thus it has 
 escaped social vigilance until within the last few years, and today 
 it presents almost insuperable difficulties. It has recently been 
 said that among the many problems of industrial hygiene, the 
 most important has hitherto been most neglected the problem of 
 industrial overstrain. Josephine Goldmark designates overfa- 
 tigue as "the commonest and most subtle danger of occupation," 
 and says that in the United States this danger 
 
 has not yet been faced nor even fairly stated ; yet no one element of industry 
 is more fraught with peril for workers. Indeed, overfatigue or exhaustion 
 surmenage as the French call it affects every department of life, physical 
 and economic, mental, moral. It predisposes to disease; it destroys intelli- 
 gence and all the habitual restraints; it cuts down output and impairs its 
 quality; it invites industrial accidents. It affects not only workers in admit- 
 tedly dangerous occupations but all workers every man, woman, and child 
 employed for excessive working hours. 4 
 
 The problem of fatigue in industry has at least six phases : 
 (a) the relation of fatigue to industrial accidents; (6) fatigue 
 and industrial inefficiency presumably poorer work and less 
 work is done in the last hour of a day's labor than in other hours ; 
 (c) fatigue and contagious diseases an overworked laboring 
 man or woman is probably more susceptible to pneumonia, tuber- 
 culosis, typhoid fever, than is a person whose vital resistance is 
 normal; (d) fatigue and nervous diseases the evidence indi- 
 cates that long hours of feverish haste among factory workers 
 lead to nervous breakdown; (e) fatigue and future generations 
 the children of overworked parents are likely to be physical 
 weaklings; (/) fatigue and morals of working people long 
 hours of monotonous labor probably increases the susceptibility 
 of the human organism to harmful temptations. 
 
 The first phase of the general fatigue problem with which 
 
 4 Josephine Goldmark, "The Study of Fatigue," Survey (1909), XXII, 534. 
 
EMORY S. BOGARDUS 3 
 
 this report is concerned' has not yet been formulated, as far as 
 the writer is aware, as a distinct problem in itself. Investiga- 
 tions relative to accidents have had largely to do with the ob- 
 jective causes ; while the more deep-seated and perhaps the more 
 primary causes have been neglected. In spite of the advance 
 which has been made in this country within recent years in the 
 introduction of safety appliances 1 and of a system of factory 
 inspection, an enormous human sacrifice is annually made to 
 production; herein lies the chief reason for this study. A few 
 typical facts are subjoined. 
 
 Crystal Eastman found that 526 lives were sacrificed to pro- 
 duction in one year, ending June 30, 1907, in Allegheny County, 
 Pa. With respect to accidents, her report says there has been 
 no respite each year has turned them out as surely as the mills 
 ran full and the railroads prospered. In Allegheny County 
 alone the number would reach 5,000 in ten years enough to 
 make a small city of cripples. 5 
 
 After carefully investigating the returns from the labor 
 offices of nine states, 6 Gilbert L. Campbell finds that these reports 
 show clearly that in the year 1907, for example, a total of at 
 least 43,713 industrial accidents befell working-men in the states 
 cited, and that 3,436 of these accidents were fatal. 7 In regard 
 to accidents befalling railway employees, Mr. Campbell bases 
 an estimate on the statistics gathered by the Interstate Commerce 
 Commission and states that during the seven-year period, 19027 
 inclusive, 335,974 employees were injured and 23,895 were killed. 
 Of the trainmen alone 218,082 were injured and 14,888 killed. 
 
 In a given year the trainman has one chance in 127 of death, and one 
 in 9 of injury. Seven years in the train service offer him one chance in 
 18 of death, and if his place is one of average danger present a practical 
 certainty of injury. 8 
 
 Industry may be charged not only with extravagance of killing and 
 
 s Crystal Eastman, Work Accidents and the Law (Charities Pub. Com., 1910), 12. 
 
 6 These nine states are: Minnesota, Iowa, Wisconsin, Illinois, Michigan, Ohio, Pennsyl- 
 vania, New Jersey, and New York. 
 
 7 Gilbert L. Campbell, Industrial Accidents and Their Compensation (Houghton Mifflin Co., 
 1911), 9, 10. 
 
 Ibid., 15. 
 
4 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 maiming yearly thousands of workers, but it seems to choose for its victims 
 many persons in the prime of manhood, normally with years of life before 
 them, and with obligations but partly discharged to wives and children." 
 
 Approximately 30,000 wage-earners are killed by accidents 
 every year and at least 500,000 more are seriously injured (in 
 the United States). 10 John B. Andrews says that industry 
 "maims more men than war ever did." Professor H. R. Seager 
 states that the United States "shows every year a larger propor- 
 tion of industrial accidents on its railroads and in its mines and 
 factories than any other civilized land." 11 Moreover, the re- 
 sultant suffering and denial of opportunity to the wives and 
 children of the daily increasing numbers of the prematurely dead 
 and of the industrially maimed and handicapped for life are 
 beyond computation. Professor Henderson asks: "Who can 
 set a price on mangled limbs, tortures of men caught in cog- 
 wheels and bands, sawed asunder in mills, and the sorrow, 
 anxiety, and despair of their impoverished families?" 12 The 
 enormous blood-tax which industry daily levies upon wage- 
 earners makes necessary new forms of careful investigation of 
 the causes, one of which may be fatigue. 
 
 Difficulties arise at the outset of this inquiry. Fatigue is an 
 illusive phenomenon. It varies with different workmen, with 
 different kinds of work, with different days. It also appears that 
 fatigue develops insidiously and often without the knowledge of 
 the worker. Moreover, physiologists and psychologists disagree 
 as to the nature of the fatigue processes. 
 
 Another kind of difficulty is common. When three well- 
 known social and economic writers (two Americans, one Euro- 
 pean) were communicated with, and asked for the references on 
 the strength of which each had published the definite statement 
 that more accidents occur in the last hours of work than in other 
 hours, no one of them could cite such references. One of the 
 frank confessions reads : "For the statement you quote, I imagine 
 now that I did not have at hand the European .statistics, and did 
 
 9 Op. tit., 21. 
 
 " J. B. Andrews, "A Clinic for Industrial Diseases," Survey, XXV, 269. 
 
 " H. R. Seager, Social Insurance (Macmillan, 1910), 25. 
 
 " C. R. Henderson, "Wood-Workers and Their Dangers," World To-Day (1910), XIX, 972. 
 
EMORY S. BOGARDUS 5 
 
 not know where to find them ; or I would have been more specific 
 in referring to them." 
 
 Attempts to collect new data are difficult. Some employers 
 have established a monopoly of knowledge and of social facts 
 facts concerning which the public should know. One day in 
 August, 1910, the writer explained to the attorney of a company 
 employing hundreds of men that data regarding accident-hours 
 were wanted. When the attorney had assured himself of the 
 bona fide nature of the inquiry and that personal data, such as 
 names, would be held strictly in confidence, he gave the writer 
 access to accident records covering a period of years and giving 
 the exact time of the accidents. A tabulation of the hours when 
 these accidents occurred was scarcely begun when a high official 
 of the company happened to enter the attorney's office. Almost 
 at a glance he unjustifiably read much into the situation and 
 gruffly said: "This is irregular; we can't have it." A courteous 
 explanation that the sole aim was to secure social facts elicited 
 no response from this apparently anti-social individual other than 
 a curt abbreviation of his first remark. 
 
 An investigation of the relation of fatigue to industrial acci- 
 dents raises difficulties which increase on every hand. On one 
 side is a series of physiological and psychological phenomena; on 
 the other, an equally involved series of objective and social 
 factors. At this point the question might easily have been raised 
 as to whether further study would bring definite results. It was 
 from such an attitude that further inquiry was made. A pre- 
 liminary study of this phase of the general problem of fatigue in 
 industry raises six important groups of questions, which will be 
 considered in as many sections. 
 
 (a) While considerable research work has been done in con- 
 nection with a study of fatigue, each of the inquiries has treated 
 the phenomenon more or less independently of its social signifi- 
 cance. Although the physiologists and especially the psycholo- 
 gists have contributed extensively to the study of fatigue, 13 the 
 writer has not seen a description of the manner in which and 
 the extent to which fatigue is psychically related to accidents in 
 
 " For example, the description of the investigations of Kraepelin and of his colaborers in 
 the laboratory at Heidelberg fill several large volumes of the Psychologische Arbeiten. 
 
6 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 industry. The discussions regarding fatigue generally stop with 
 analyses of subjective processes. They do not deal with fatigue 
 as a social problem or consider it in relation to a special group 
 of social phenomena such as accidents. 14 Is there not a need, 
 then, for a concise description of what the physiologists and also 
 the psychologists have discovered that may be used in a study 
 of fatigue as a cause of accidents ? The question that is raised 
 here calls for the formulation of a law of the development of 
 the fatigue processes which accompany continued work, in so 
 far as they may be related to accidents. 
 
 (&) In the next place, how does modern industrial labor affect 
 the normal development of fatigue in what ways is the devel- 
 opment of the fatigue process hastened in the case of present- 
 day working people, and why; and what are the observable 
 circumstances under which these processes result in accidents? (c) 
 Can the subjective fatigue processes be measured by means of 
 controlled experiments in terms comparable to the observable 
 conditions preceding accidents, and thus be causally related to 
 accidents ? 
 
 (d) The fourth question is: What are the objective corre- 
 lates of fatigue in terms of actual accidents, or to what extent 
 do statistics of the hours when accidents occur isolate fatigue 
 from the other and more evident causes? (e) Has over fatigue 
 attracted attention to itself to the extent that men of the busi- 
 ness and legal world have pronounced it a cause of accidents? 
 Specifically, to what extent do investigations of the causes of 
 railway accidents, for example, by the Interstate Commerce Com- 
 mission, isolate fatigue as a cause of accidents; and have the 
 courts indicted fatigue as a cause of accidents ? 
 
 (/) In the last place, should not all the facts relative to this 
 problem be brought together in a unified whole? The facts de- 
 rived (i) from a study of the normal development of fatigue, 
 (2) from a study of pathological fatigue under modern indus- 
 trial conditions, (3) from an experimental study of fatigue under 
 
 14 The Brief in Defense of the Ten-Hour Law for Women in Illinois (1909), by Louis D. 
 Brandeis, assisted by Josephine Goldmark, contains an excellent compilation of opinions from 
 European and American sources regarding different social phases of the fatigue problem. The 
 brief has served as a valuable reference work in the preparation of portions of sections II, III, 
 and V of this study. 
 
EMORY S. BOGARDUS 7 
 
 controlled conditions, (4) from a statistical inquiry into accident- 
 hours, and (5) from a compilation of legal opinion relating to 
 the problem in hand; will be summarized and presented in de- 
 fense of the proposition that fatigue is a cause of industrial acci- 
 dents. To the extent that the facts show that fatigue is a causal 
 factor of work-accidents, a modified method of combating their 
 prevalence will be necessary. One general suggestion in this con- 
 nection will be made. In the next section a description of the 
 development of the fatigue processes which may lead up to and 
 culminate in industrial accidents will be undertaken. 
 
 II. RELATED FATIGUE PROCESSES 1 
 
 Mosso was among the first to point out in a scientific way 
 the fatal struggle between the machine-operative, subject to the 
 laws of fatigue and exhaustion, and the machine itself, powerful 
 and indefatigable. 2 He designates fatigue as a chemical process. 
 The earliest experiments relative to fatigue were of a chemical 
 nature. 
 
 Normal muscle-tissue has the power of changing the sugar 
 brought to it by the blood into glycogen (C 6 H 2 O 6 H 2 O= 
 C 6 H 10 O 5 ). The muscle stores away the glycogen thus formed 
 and it becomes a constant constituent of a normal muscle. The 
 glycogen which the muscle has stored away while resting is con- 
 sumed during activity. If the activity is sufficiently prolonged, 
 the glycogen disappears entirely and exhaustion of the muscle is 
 likely to result. It has been shown by verified experiments that if 
 most of the carbohydrate (or glycogen) be removed from the 
 body of an animal, the organism gives the 'Symptoms of "pro- 
 nounced fatigue." 3 The same result holds true of individual 
 muscles. 
 
 Without doubt, during muscle activity there is a constant 
 
 1 This sketch of the fatigue processes is such as appears preliminary to the formulation of 
 a causal law of fatigue underlying industrial accidents. Only the material germane to a clear 
 understanding of the chapters which follow is presented here. 
 
 1 "Le savant professeur (Mosso) nous montre la lutte inevitable fatale, entre la machine 
 puissante, infatigable et aveugle et 1'ouvrier charge de la conduire, de la guider, mais qui lui, 
 organisme vivant, est soumis aux lois de la fatigue et de 1'epuisement." P. Langlois, Introd., 
 trans, of Mosso's La fatigue intellectuelle (Paris, 1904), 12. 
 
 J F. S. Lee, "The Nature of Fatigue," Pop. Sci. Mon., LXXVI, 185, 186. 
 
8 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 drain upon the material from which muscle-energy is obtained. 4 
 There is a growing loss of power to absorb nutriment from the 
 blood, and a continual tearing down without equal building up. 
 After repeated muscle contractions, the processes of katabolism 
 (tearing down) are in excess of those of anabolism (building 
 up) ; and prolonged muscular activity is accompanied by an 
 "exhaustion of energy-yielding material/' It should be added 
 that this exhaustion process goes on not only in the groups of 
 muscles which are being visibly used, but also in the groups of 
 muscles in different parts of the body which are held tense and 
 unrelaxed in guiding the groups of visibly working muscles. 
 
 Besides, the mentioned structural changes which accompany 
 work 5 occur not only in muscles but in nerve-cells. Physio- 
 logical evidence indicates that during mental and muscular ac- 
 tivity nerve-cells undergo actual structural changes. 6 (a) The 
 nucleus of the nerve-cell shows marked decrease in size; it 
 changes from a smooth and round to a jagged, irregular outline ; 
 it loses its open, reticulate appearance, (b) The protoplasm of 
 the nerve-cell shows a slight shrinkage, and undergoes vacuola- 
 tion. (c) The cell capsule suffers a decrease in the size of its 
 nuclei. These results were obtained from a study of spinal 
 ganglion and brain-cells electrically stimulated and of those in 
 a state of fatigue produced normally. For certain of these 
 nerve-cells, Hodge found that a period which varied from seven 
 to twenty-four hours was necessary before the cells returned to 
 their previous shape and appearance. 
 
 Guerrini's experiments corroborated Hodge's results. He ex- 
 amined microscopically the brain-cells of animals fatigued by 
 muscular work. The more the animal had been fatigued 
 
 the more profoundly altered the nerve-cells of its cerebral or cerebellar cor- 
 tex were found to be. These are, briefly, the modifications which fatigue 
 
 4 W. H. Howell, A Text-book of Physiology (Saunders Co., 1909), 71. 
 
 * It is not intended to make a definite distinction here between mental and muscular 
 fatigue. In all forms of hazardous labor the mental and muscular factors are both inextricably 
 involved as parts of one bodily process, but of course in varying degrees. 
 
 'See D. F. Hodge, "A Microscopical Study of Changes Due to Functional Activity in 
 Nerve Cells," Jour, of Morpkol., VII, 95-168; also "Some Effects of Electrically Stimulating 
 Ganglion Cells," Amer. Jour, of Psych., II, 376-402; also A. G. Levy, "Fatigue of the Cerebral 
 Motor Cortex," Brit. Med. Jour. (1900), 741. 
 
EMORY S. BOGARDUS 9 
 
 produces on the microscopic structure of the nerve-cell, and more evidently 
 in that of the cerebral than in that of the cerebellar cortex, and most of all 
 in the structure of those nerve-cells which correspond to the motor zones. 7 
 
 This progressively exhaustive chemical process has another 
 significant phase for this paper. As a result of his experiments, 
 Ranke came to the belief that certain substances which inhibited 
 the power of muscular contraction were formed as a result of 
 the chemical processes occurring during contraction. He named 
 these, "fatigue substances" ("ermiidenden Stoffe"). 8 
 
 In the extracts of normal muscle, parcolactic acid (C 3 H 6 O 3 ) 
 is found but slightly, while the amount greatly increases during 
 muscle activity. Mosso calls attention to the fact that before 
 the close of the i8th century Lavoisier and Sequin, by a series 
 of memorable chemical analyses, demonstrated that muscular 
 work increased the amount of carbonic acid eliminated from the 
 system. A laborer expires nearly twice as much carbon dioxid 
 during a working day as during a resting day. The carbon 
 dioxid results from the oxidation of the carbon found in the 
 constituents of the muscle. Monopotassium phosphate ( KH 2 PO 4 ) 
 is another of the important and definitely determined fatigue sub- 
 stances. 9 These substances seemed to be formed also in the 
 nerve-cell during activity. 10 
 
 In the next place, the fatigue substances mentioned exert a 
 poisonous and paralysing effect upon the whole organism. Both 
 parcolactic acid and carbon dioxid "when in any but small quan- 
 tity are inimical to protoplasmic activity, and furthermore, .... 
 a muscle under their influence shows the very same physical 
 symptoms that are shown by a muscle fatigued through work." 
 After investigating a large amount of testimony from physicians 
 and physiologists, both European and American, Brandeis and 
 Goldmark state: 
 
 They [the unexpelled products of fatigue] circulate in the blood, poison- 
 ing brain and nervous system, muscles, glands, and other organs until normally 
 
 removed by the oxygen of the blood, by the liver or kidneys When 
 
 they exceed their physiological or normal amount, exhaustion results 
 
 7 Guido Guerrini, "Preliminary Account of the Influence of Fatigue on the Structure of 
 the Nerve-Cells," Lancet, II, 1087. 
 
 1 J. Ranke, Tetanus (Leipzig, 1865), chap, xv, "Die einzelnen ermudenden Stoffe." 
 ' Howell, op. cit., 70. 10 Ibid., 139. 
 
10 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 In extreme instances of overexertion death results, not from sheer ex- 
 haustion of the heart, but from chemical poisoning due to the unexpelled 
 products of fatigue. 11 
 
 In this connection, Dr. H. B. Favill says : 
 
 Any living organism will die promptly if the waste products (including 
 the fatigue substances) from its life processes accumulate Laboratory- 
 research, verified by many competent observers, indicates that there are 
 created in the process of muscular work .... substances of a nature dis- 
 tinctly poisonous. 12 
 
 Besides the fatigue substances mentioned, Weichardt states 
 that muscular contraction produces a definite toxin (keno- 
 toxin). 13 He found kenotoxin in the muscle juices ("Muskel- 
 preszsaft") ; and in addition to the known fatigue substances. 
 When injected into an animal, kenotoxin produces fatigue; in 
 large doses it causes death ("wirkte er ermiidend und in groszen 
 Doses, todtlich"). Weichardt has definitely isolated both keno- 
 toxin and its antitoxin ("beide Substanzen, habe ich isoliert 
 dargestellt und zu ausgedehnten Versuchsreihen verwendet")- 
 These results have been verified by Dr. Wolff-Eisner. 14 They add 
 weight to the fact that the known fatigue substances possess a 
 toxic and paralyzing nature. 
 
 It appear that the fatigue poisons accumulate first, not in 
 the muscles actually moving but in the groups of tense, non- 
 moving muscles, which are used in guiding the given activity. 
 These muscles are poorly irrigated. But sooner or later the 
 fatigue substances accumulate in the moving muscles, even though 
 these are better irrigated. The toxins also circulate in the blood 
 throughout the body. Howell describes the twofold chemical 
 process accompanying work as (a) an exhaustion of energy- 
 yielding material, and (b) an accumulation of the products of 
 katabolism (the fatigue substances). 15 Verworn refers to the 
 
 11 L. D. Brandeis (assisted by Josephine Goldmark), The Brief in Defense of the Ten-Hour 
 Law for Women in Illinois (1909), 77, 78. 
 
 " H. B. Favill, "The Toxin of Fatigue," Survey, XXIV, 769. 
 
 13 See W. Weichardt, "Ueber das Ennudungstoxin und Antitoxin," Munch, med. Wochenschr., 
 LI, 2122-26, LII, 1234-36; "Ermudungs- und Ueberermuduncsmaszmethoden," Deutsche 
 Vierteljahrschr.f. ojfentl. Gesundheitspjl., XXXIX, 324-34- 
 
 14 See A. Wolff-Eisner, "Ueber Ermudungs- und Reduktionstoxine," CentralbLf. Bakteriol., 
 i Abt., XL, 634-44- 
 
 15 Howell, op. cit., 71. 
 
EMORY S. BOGARDUS II 
 
 using up of energy-yielding material as culminating in "Erschop- 
 fung" a literal exhaustion; and to the production of fatigue 
 substances as resulting in a state of "Ermudung." 16 The change 
 that takes place in the reaction of an active muscle, in the size of 
 an active nerve-cell, and in the amount of waste material thrown 
 off by the organism when it becomes active, leaves little room 
 to doubt that there is a direct relation between structural changes 
 and activity. 
 
 ^" This conclusion brings up the related functional changes ac- 
 companying work. For the purpose of this istudy, the fatigue 
 process may be treated as centering around the objective phe- 
 nomenon of increasing muscular inaccuracy. Because of the 
 using up of muscle material and because of the accumulation in 
 the muscles of the fatigue-toxins, a given group of working mus- 
 cles gradually become less able to respond to the demands made 
 upon them by the psychical-neural apparatus. If rapidly repeated 
 stimuli of equal strengths at equal intervals be applied to a mus- 
 cle, it is found that at first the contractions increase in extent 
 (forming the "treppe"), that after a certain period the contrac- 
 tions begin to diminish steadily in height until finally the muscle 
 will fail to respond to the stimulus. This progressive loss of ir- 
 ritability in the muscle, caused by repeated activity, has been 
 designated as fatigue. 17 
 
 Ergograph experiments (where the stimulation of the muscle 
 is not artificial, but voluntary) show that after a state of complete 
 fatigue has been reached with a given task, a very long interval 
 is necessary for the muscle to make complete recovery. 18 Mosso 
 lays stress on the fact that Professor Maggiora proved that two 
 hours' rest is necessary before the fatigue traces are completely 
 removed from the flexor muscles of the fingers after they have 
 been exhausted by a series of contractions in the ergograph. 19 
 
 Maggiora found that the last smaller contractions of muscles 
 are more exhaustive than the first large contractions. 20 After 
 
 '* Max Verworn, Allgemeine Physiologic (Jena, 1909), 557. 
 17 Howell, op. cit., 34, 35. 
 
 11 Ibid., 49. The ergograph is a special instrument devised by Mosso, by means of which 
 the muscle is given a specific work to do, such as lifting a weight. 
 
 "A. Mosso, Fatigue (Paris, 1904), trans, by the Drummonds, 150. 
 
 " A. Maggiora, "Ueber die Gesetze der Ermudung," Arch.f. Anat. u. Physiol. (1800), 213. 
 
12 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 muscles are completely fatigued, still further efforts to contract 
 them greatly prolong the period of complete recovery. Work 
 which calls for contractions of tired muscles is much more in- 
 jurious ("viel schadlicher") than greater muscular tasks under 
 normal conditions. 21 Verworn states that a fatigued muscle re- 
 quires a considerably longer time ( "unvergleichlich mehr Zeit") 
 for relaxation than does a normal muscle. 22 It is the long in- 
 terval of recovery, a period unduly long for the removal of the 
 katabolic products due to the activity of a single muscle, which 
 leads to the belief already cited that fatigue is partly due to con- 
 sumption of muscle-material itself, which has to be replaced by 
 anabolic or building-up processes before the muscle is entirely 
 free from fatigue effects. 23 
 
 Other things being equal, the rate at which the working mus- 
 cle becomes less responsive to stimulation depends (a) upon the 
 rapidity and (b) upon the difficulty of the given piece of work. 
 Kronecker found that the more rapid is the rhythm in which mus- 
 cular contractions are produced, the more rapidly does the height 
 of these contractions diminish; and vice versa. 24 By using the 
 ergograph, Winfield S. Hall found that if a muscle be given a 
 load proportional to the actual strength of the muscle and if 
 the muscle be allowed to rest from the strain of the weight 
 during the period of relaxation, the time of the fatiguing process 
 may be indefinitely prolonged. 25 
 
 Not only do working muscles become less able to respond to 
 stimulation because of fatigue, but they receive less and less effi- 
 cient stimulation from the psychical-neural apparatus. It appears 
 that with the exhaustion of energy-giving material and with the 
 accumulation of the toxic fatigue substances in the parts used 
 and in those portions of the muscles located at any place in the 
 body that are under tension in guiding the activity of the mus- 
 cles that are working, inhibitory impulses ascend along the affer- 
 ent fibers, with which every muscle and tendon is supplied, to 
 
 " Op. cit., 211. " Max Verworn, op. tit., 548. 
 
 " W. H. Howell, op. tit., 71. 
 
 14 See C. S. Yoakum, An Experimental Study of Fatigue (The University of Chicago Press, 
 1009), 3. 
 
 ts W. S. Hall, Bulletin (Northwestern Medical School, Chicago). 
 
EMORY S. BOGARDUS 13 
 
 the motor centers of the cortex and cord. Myers says that the 
 afferent fibers running from the muscular (and other) tissues 
 of the body to terminate around the cells of the motor nuclei of 
 the cord, bulb, and mid-brain, play an important part in reflexly 
 co-ordinating muscular action. 26 The various motor centers of 
 the cord which control the movements of flexion and extension 
 are alternately excited or inhibited, owing to the play upon them 
 of afferent impulses peripherally derived from the movements 
 themselves. Whatever disturbs these afferent impulses disturbs 
 muscular co-ordinations. The using up of muscle material and 
 the accumulation of fatigue substances appear to increase the 
 inhibitory action of afferent impulses. 
 
 The neural apparatus also becomes less efficient in guiding 
 the working muscles because of the structural changes going on 
 in the nerve-cells. Dearborn says that nerve-cells do become ex- 
 hausted progressively, however slowly, even in cases where their 
 blood-supply is ample and their vigor normal. 27 Tigerstedt says 
 that by a method especially adapted to the purpose it may be 
 shown that the nervous mechanism is being greatly strained be- 
 fore there is any sign of fatigue in the external work done. 28 
 In summing up the situation regarding nerve-cell fatigue, it may 
 be said that it seems probable that under normal conditions some 
 portions of the nerve centers remain in more or less constant 
 activity during the day without showing a marked degree of 
 fatigue, just as muscles remain in a more or less continuous state 
 of contraction throughout the waking period. 29 But when the 
 nerve centers are strongly stimulated the fatigue is more marked 
 "because the processes of repair in the nerve centers cannot then 
 keep pace with the processes of consumption of materials." 30 
 
 Another factor which affects the efficiency of the neural appa- 
 ratus in guiding the active muscles, has been mentioned, namely, 
 the poisoning and paralyzing effect of the fatigue substances 
 
 * C. S. Myers, Experimental Psychology (Longmans, Green & Co., 1909), 186. 
 
 37 G. V. N. Dearborn, "On the Fatigue of the Nerve Centers," Psych. Rev,, IX, 182; see 
 also W. H. Burnham, "The Problem of Fatigue," Amer. Jour, of Psych., XIX, 385. 
 
 * R. Tigerstedt, A Text-book of Human Physiology (Appleton, 1006), trans, by Murlin, 
 446. 
 
 "Howell, op. cit., 138. "Ibid. 
 
14 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 which circulate through the brain and other centers of control. 
 The structural and functional fatigue changes which have been 
 described may be briefly summarized at this point. Not only do 
 muscles become less responsive to stimulation (because of the 
 using up of energy-giving material and because of the paralyzing 
 effects upon them of the fatigue substances), but the muscles 
 receive less and less efficient stimulation from the neural appa- 
 ratus (because of the effects upon the neural apparatus by the 
 inhibitory impulses from both the tense and the moving muscles, 
 by the structural changes in the spinal ganglion and central nerve- 
 cells, and by the poisonous fatigue substances circulating through 
 the higher neural centers). 
 
 The combined effects of these forces result in increasing mus- 
 cular inaccuracy. Muscular co-ordinations become seriously ham- 
 pered and irregular. The loss of control over the muscular 
 co-ordinations consists first in "the immeasurably short shifts 
 and 'blockings' of the more finely adjusted musculature .... 
 on to the grossest muscular contractions that finally cease to 
 respond to the effort of the will. 5 ' 31 
 
 Loss of muscle control as indicated by the progress from 
 blocking of the more finely adjusted musculature on to failure 
 to make the grossest muscular contractions is not adequately 
 represented by a continuous descending slant. Increasing fatigue 
 when brought to the notice of the worker leads to tempo rary 
 spurts, that is to say, to an increase in the volitional strain or at- 
 tention which he brings to bear on his task. Although the fatigue 
 process may go on for a time unnoticed, it sooner or later appears 
 in consciousness in the form of "sensations." These sensations 
 may arise first as feelings of effort, then as feelings of strain, 
 then as sensations of fatigue. 32 The fatigue sensations are warn- 
 ings. They indicate that the organism demands "a shift in the 
 working mechanism." By tremendous effort, a fatigued worker 
 may for a short time bring to his labor a striking degree of vo- 
 litional attention. 
 
 These spurts appear irregularly, and there are alternating 
 and irregular periods of depression or bad spells -when the worker 
 
 ' Yoakum, op. cit., 114. Ja Ibid., 117. 
 
EMORY S. BOGARDUS 15 
 
 is less able to give attention and when the co-ordinations are less 
 likely to be .correct than during the periods of volitional strain. 
 Beyond doubt, the periods of depression are due to flagging 
 interest and increasing fatigue. 33 Hence, during uninterrupted 
 work and as soon as fatigue effects predominate over skill due to 
 practice, there sets in an irregularly decreasing control over mus- 
 cle co-ordinations. The time at which fatigue is likely to over- 
 come practice during a given period of work depends among other 
 things upon the rate and difficulty of the work, as already noted, 
 for the given individual. At the beginning of a period of unin- 
 terrupted work there is likely to be uncertain muscle control, due 
 to the necessity of getting "warmed up" and occasionally to 
 nervous excitement attendant upon beginning a piece of work. 
 Then for a certain length of time the muscle control is likely 
 to be good due to practice effects. 34 When practice gain is 
 overcome by fatigue effects, then muscular inaccuracy becomes 
 a developing and important factor. During this period effort is 
 expended in waves of force that approximate what Treves calls 
 the irregular progress of mental fatigue rather than the regular 
 decline of muscle power. 35 
 
 Muscular inaccuracies may be of two kinds : one may keep up 
 with the rhythm of work and make spatial maladjustments; or 
 one may make accurate spatial movements, and fall behind the 
 rhythm; or one may do both. Thus muscular inaccuracies may 
 be not only of a spatial nature, but may involve a time element as 
 well. Mosso says: 
 
 The time of physiological reaction .... is the name given to the inter- 
 val between the occurrence of an electric spark, for instance, and our giving 
 some sign of having perceived it, say by touching an electric button on which 
 our hand rests. This short space of time .... represents the delay which 
 takes place before we take account of one of the most simple forms of per- 
 ception Fatigue has great influence on the duration of this reaction 
 
 time. When such measurements are repeated without an interval for rest, 
 the time before the response is given gradually increases. 86 
 
 M Myers, op. cit., 194. 
 
 34 A. Binet, La fatigue intettectuelle (Paris, 1898), 334; also E. Kraepelin, Philos. Studien, 
 XIX, 459-507. 
 
 " Yoakum, op. cit., 42. 
 36 Mosso, op. cit., 205. 
 
1 6 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 A delay in promptness of reaction 37 and a greater number of 
 faults of memory and attention are noticeable after fatigue. 38 
 It is almost impossible to be attentive when the brain, for in- 
 stance, is fatigued. 39 The length of time that ordinarily elapses 
 before one responds with the hand, for example, to a touch 
 on the foot may be doubled as a result of the effects of fatigue on 
 attention. 40 
 
 ^The effect of fatigue on attention which is such an impor- 
 tant factor in failure to make accurate muscular co-ordinations 
 appears to have its basis in the difficulty of maintaining the ten- 
 sions which are guiding the given activity." It is not possible to 
 maintain one set of tensions long without physiological changes 
 taking place. And any physiological changes may while they 
 are still subconscious be the "cue" for a change of attention to 
 some other topic of thought, a change which may involve a new 
 set of tensions and thus the process continues. Or, the physio- 
 logical changes referred to may come to consciousness in the 
 form of sensations of fatigue, and in this case there is a change 
 of attention to the point of origin or to the sensations themselves, 
 and vigilance over muscular movements is temporarily suspended. 
 V In the case of monotonous division of labor where the work- 
 man must attend continually to one single uninteresting point or 
 part of a machine the same neural-muscular apparatus must be 
 used, the same tensions must be maintained. The difficulty of 
 maintaining this situation with little if any variation becomes 
 increasingly great. If the task in hand requires constant atten- 
 tion, increasing muscular inaccuracy is likely to result imme- 
 diately due to the effects of fatigue on attention. The degree of 
 muscular inaccuracy is determined partly by the inability of mus- 
 cles to respond according to their state of wear and tear and 
 to the amount of fatigue substances which have accumulated 
 and partly by the inability of the neural apparatus to attend to 
 
 17 "Reaction time includes such phenomena as (a) the latent period in the sense organ, 
 (6) time of transmission along the afferent nerve, (c) resultant processes within the central 
 nervous system, (d) time of transmission along the efferent nerve, and (e) the latent period in 
 the muscle." J. M. Cattell, "The Time Taken by Cerebral Operations," Mind, XI, 230. 
 
 11 Z. Treves, "Dans quelle mesure peut-on, par des methodes physiologiques, etudier la 
 fatigue,'* etc., 13* Cong. Intern. d'Hyg. et Demog., V, sec. 4, ques. 3, p. 37. 
 
 39 Mosso, op. cit., 198. 4 * Ibid., 205. 
 
EMORY S. BOGARDUS 17 
 
 the movements of the given muscles according to the number 
 of and the state of the tensions which can be relied upon in 
 guiding the given activity. 41 
 
 Muscular inaccuracy is increased especially where the regular 
 effects of fatigue on attention are augmented by a general con- 
 dition of over fatigue of the whole system, that is to say, by a 
 state of chronic overfatigue. Pathological fatigue also results in 
 "increasing inaccuracy of judgment," 42 which in turn increases 
 muscular inaccuracy. Overwork blunts all the psychic activities 
 and diminishes sensibility; and hence diminishes the precision of 
 movements and the exactness of the rhythm. 43 
 
 It has been pointed out in this section that uninterrupted mus- 
 cular work results in using up of energy-yielding material of 
 muscles and of nerve-cells, and in the accumulation of toxic 
 waste substances, with an accompanying decrease in muscle irrita- 
 bility and activity, and inability of the neural apparatus to attend 
 to muscle movements, i.e., with a corresponding and increasing 
 irregularity in the co-ordination of muscular action.^ The rate 
 X at which these various phases of the fatigue process takes place 
 is dependent on the rate and difficulty including monotony 
 of the given task.J 
 
 If stated in terms of the subjective conditions which the 
 writer believes quite generally precede accidents, a summary of 
 this chapter may be given psychological expression. The re- 
 sultant and germane law of fatigue i^i Uninterrupted muscular 
 activity is accompanied by inaccurate muscular co-ordinations, 
 which increase irregularly and at a rate largely determined by 
 the speed and relative difficulty of the activity for the given 
 individual.} 
 
 41 See Yoakum, op. tit., 99-124; also Myers, op. cit., 186 ff. 
 
 4 * E. W. Scripture, "Researches in Reaction Time," Yale Studies, IV, 12-16, 69-75. 
 
 41 J. de Moor, 13. Intern. Kongr.f. Hyg. u. Demog., Pt. I, 5, sec. 4, ques. 3, p. 9. 
 
1 8 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 III. RELATED INDUSTRIAL CAUSES OF ACCIDENTS 
 
 After a study of the related subjective processes accompany- 
 ing work had been made and after the formula given at the close 
 of section II had been determined upon, the writer supplemented 
 a previous limited experience by spending considerable time in 
 visiting factories and shops in and about Chicago. The purpose 
 was to test the conclusions already in mind and to observe more 
 accurately the conditions which precede accidents. Eleven fac- 
 tories and shops were visited, representing as many forms of 
 industry. 1 Permission was obtained to wander leisurely about 
 and thus unnoticed to observe operatives of dangerous machines 
 while at work. About twenty types of dangerous machines were 
 found. 2 Three accidents were directly witnessed two at solder- 
 ing machines and one at a press and drill. 
 
 As a result of these observations it appears to the writer that 
 thejchief industrial conditions leading up to and culminating in 
 V accidents are those of monotony and speed and of unrelated 
 tension, kept up for long hours. This process seems to result 
 in increasing numbers and extent of muscular inaccuracies, which 
 in turn appear to be the phenomena immediately preceding acci- 
 dents. This view in more or less detail will be supported in this 
 section. 
 
 Proof is hardly necessary to show that monotony and great 
 speed characterize the conditions under which operatives of 
 dangerous machines work. In most industries, labor is so sub- 
 divided that each worker has but one small part to do. This 
 part is repeated thousands of times daily. To make a small 
 sickle section, for example, requires thirty operations by as many 
 men and boys. Certain parts of this process make vivid the 
 factors of monotony and speed. 
 
 A man feeds metal sheets into a machine that cuts them out in a three- 
 cornered form, 20,000 per day .... one motion is required for each sheet. 
 
 1 These included the packing, canning, and steel industries; leather-goods and knitting 
 establishments; steel-castings and box factories; various wood- working and metal- working 
 concerns, and wagon shops. 
 
 1 Among these types are those represented by the press and drill, the press and die, revolv- 
 ing knives, saws, stamping and cutting machines of various forms, and soldering machines. 
 
EMORY S. BOGARDUS 19 
 
 The two holes of the sickle section, when punched, are slightly enlarged 
 on one side to receive the head of the rivet, 7,000 per day. Along one side 
 of the room in which the edges of the sickle section are beveled are arranged 
 a row of grindstones six feet across. In front of these whirring stones sit 
 a line of powerful, heavy-faced men, not a spark of animation in their faces. 
 They are each doing the same thing; they drop one of these plates into the 
 slot of the frame, shove the frame against the rapidly revolving stone and 
 then draw it back; drop, shove, draw back .... 5,000 times each day. In 
 the room where the sections are serrated, a row of young men stand, feeding 
 machines which run at great speed and with deadening noise. These machines 
 cut the teeth on the bevel edge of the plate, 7,000 plates a day. 
 
 These monotonous, speeded-up operations in connection with 
 dangerous machinery are found in "the manufacture of nearly 
 every article of use or comfort with which our lives are sur- 
 rounded ; in the manufacture of that piano, the chair you are sit- 
 ting on, the watch in your pocket, the car you ride in, the sewing 
 machine, the meat you ate for your breakfast this morning." 
 
 In the canning factories of Pittsburgh, for instance, where 
 tops for cans are cut from sheets of tin, the foot-press operator 
 puts the sheets in the press, gauges it so that it will fall evenly, 
 gives a quick pressure of the foot in order to clip the tin for 
 each top. This quick pressure and accompanying hand move- 
 ments are repeated "forty times a minute, 24,000 times a day." 3 
 Ernst Abbe points out that 
 
 with this sameness ("Gleichformigkeit") and continually recurring monotony 
 ("Einformigkeit"), we also get the continuous ("fortgesetzte") fatigue of 
 the same organ, of the same nerve centers, and of the same part of the brain 
 .... because all that is to be done, whether muscular or mental work, must 
 be constantly repeated ("sich wiederholen") in the same manner from morn- 
 ing to night, day by day, and week by week.* 
 
 s Today, the necessary rapidity of monotonous motions fa- 
 Xtigues workers and causes accidents. Dr. Thomas Oliver regrets 
 the attempt to americanize shipbuilding in England for the rea- 
 son that this "rushing" is a cause of serious accidents. 5 Pro- 
 fessor G. Pieraccini and Dr. R. Maffei, Florence, state that piece- 
 work, which necessitates higher speed, tends, both in itself and 
 
 * Eliz. B. Butler, Women and the Trades (Charities Pub. Com., 1909), 36. 
 4 E. Abbe, Gesammelte Abhandlungen (Jena, 1906), HI, 225. 
 s T. Oliver, Diseases of Occupation (London, 1908), 3. 
 
20 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 together with the fatigue that ensues, to favor the occurrence of 
 labor accidents. 6 It is no exaggeration to say that the pace kills 
 andjnjures more people than labor peruse.. To the extent that 
 the stupefying effects of monotony and the confusion attendant 
 upon "speeding up }} are added to the regular development of the 
 fatigue process, loss of muscular control and danger of accident 
 are increased. 
 
 A characteristic phase of monotony and speed is unrelaxed 
 tension of the worker. Arlidge says that the fatigue of machine 
 operatives is more the fatigue of watching than that of working. 7 
 From a psychological standpoint, it is impossible to attend to 
 very many things at a time or to attend to one thing for very 
 long at a time. It is especially fatiguing to keep the attention 
 on a simple process which presents no new phase, but which is 
 a continuous repetition of a few simple movements hour by hour. 
 It is true, of course, that these movements tend to become auto- 
 matic ; but when they must be made in close proximity to danger- 
 ous and rapidly revolving tools, a certain degree of voluntary 
 attention must be exercised, or else injury will result during a 
 moment of inattention. 
 
 Professor Henderson states that the speed of saws, for 
 instance, is a -significant factor in increasing danger, "because 
 the swift movement increases the strain upon attention and so 
 
 X rapidly exhausts nervous energy." 8 The relaxation of tension 
 which sometimes results in serious injury, says Elizabeth B. 
 Butler, may be accounted for by the hurry of the worker who 
 is usually ambitious, or by the weariness toward the end of the 
 five hours' continuous work. 9 
 
 ^ Operatives of machinery become accustomed to the presence 
 of danger and hence less on their guard against the effects of 
 fatigue on attention. Cadbury says that workers accustomed to 
 danger are apt to look away to talk to their companions and in 
 
 * See Brandeis and Goldmark, Ten-Hour Law for Women, 75. 
 
 T J. T. Arlidge, The Hygiene, Diseases and the Mortality of Occupations (London, 1892). 
 C. R. Henderson, "Wood-Workers and Their Dangers," World To-Day, XIX, 975. 
 
 Eliz. B. Butler, op. cit., 22 . 
 
EMORY S. BOGARDUS 21 
 
 a moment of relaxed tension the hand is caught under the ma- 
 chine. 
 
 The incessant noise of the machinery, the excessive monotony of the 
 {/ work, and above all, the long hours, which are too often spent in an ill- 
 lighted and ill-ventilated atmosphere all tend to produce a depressing and 
 deadening effect which cannot fail to destroy the alertness of attention. 10 
 
 In the steel mills, for example, an alert mind is the first re- 
 quirement for safety. 11 There, as elsewhere in connection with 
 dangerous work, attention is focused more on the proper accom- 
 plishment of the work than on self -protection. But attention 
 to the matter of self -protection in steel mills is comparable to an 
 attempt to dodge bullets on the battlefield. Neither a steel- 
 worker nor a soldier of that type can long retain the respect of 
 his fellows. Attention to self -protection is bound to be sec- 
 ondary and incidental; but to insure the workman's safety it 
 must be constant and keen. However instinctive this vigilance 
 may be, it cannot be considered unfailing. The speed^and in- 
 tensity of the work, the .heat and noise of the steel mill, TEe 
 weariness of the workers, "all these things tend to numb the 
 faculties most needed for protection." 12 
 
 As a result of continuous and unrelaxed tension, the fatigue 
 processes go on insidiously. The onset of fatigue is often un- 
 perceived. The tension in modern industry calls out the voli- 
 / tional power which urges on a fatigued worker, intensi- 
 fies application, and minimizes the sensation of effort, thus 
 concealing fatigue. Kirkpatrick emphasizes the fact that a per- 
 son often does not feel weary after his power to act has been 
 very much decreased. 13 The distinction which must be made 
 between the sensations which supervene during the performance 
 of the work and the lowered capacity for work as shown ob- 
 jectively by diminution in the amount of work executed is well 
 known. Rivers says that there may be complete absence of any 
 sensations of fatigue, when the objective record. shows that the 
 
 " Edw. Cadbury and others, Women's Work and Wages (The University of Chicago Press 
 1907), S3- 
 
 " Crystal Eastman, Work-Accidents and the Law (Charities Pub. Com., 1910), 91. 
 
 "Ibid. 
 
 1J E. A. Kirkpatrick, Fundamentals of Child-Study (Macmillan, 1009), 322. 
 
22 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 work is falling off in quantity, or in quality, or in both. 14 The 
 curve of organic fatigue follows a different outline than that 
 which represents the production of voluntary work. 15 
 
 Workmen are generally ignorant of the difference between 
 the subjective development of fatigue, and its objective corre- 
 lates. Unrelaxed tension in modern industry makes continuous 
 and terrible demands on the human volitions. These, in turn, 
 so intensify application and minimize warnings of overfatigue 
 that the worker in the dangerous trades may suddenly through 
 inaccurate movements find himself handicapped for life, or the 
 wife and children may receive the unexpected message that their 
 breadwinner has given up his life while serving at the post of 
 duty. 
 
 The terrific mental strain due to monotony and speeding up 
 js doubly vicious because of the fact of long hours, After a 
 certain period of time, varying in length with different indi- 
 viduals, unrelaxed tension cannot be consistently maintained, un- 
 certainty of movements increases, and danger of accidents multi- 
 plies. After making a careful investigation of work-hours, the 
 National Conservation Commission says : "The present working 
 day from a physiological standpoint is too long, and keeps the 
 majority of men and women in a continual state of overfatigue. 16 
 .... The manual worker through fatigue caused by long hours 
 is in a continual state of overexertion! }Yl 
 
 The situation is especially grave when the men and women 
 kept in a continual state of overfatigue because of long hours 
 are operatives of dangerous machinery. Further, in many in- 
 dustries where danger exists, the long hours of regular employ- 
 ment are supplemented by demands for "overtime" work during 
 certain parts of the year. In Pittsburgh, for example, Elizabeth 
 Butler found that many canning factories work every night until 
 ten o'clock during the busy season, making a working week 
 of over 72 hours. 18 One manager admitted that the girls 
 
 M W. H. Rivers, The Influence of Alcohol, etc., on Fatigue (London, 1908), 2. 
 
 15 T. Oliver, Dangerous Trades (London, 1902), 117. 
 
 16 Senate Document No. 419, 6ist Cong., 2d sess. (1910), 626. 
 
 17 Ibid., 666. 
 
 18 Eliz. B. Butler, op. cit., 39, 40. 
 
EMORY S. BOGARDUS 23 
 
 under his direction " worked 75 hours a week for two months 
 every year." He added that the factory inspectors generally 
 did not interfere; that they usually come around in September 
 and after the holidays, and "they never see any overtime." 19 In 
 another factory where foot-press work was the chief type of 
 labor, Miss Butler found that the employees are sometimes 
 forced to work twelve and fourteen hours and "accidents are 
 so frequent that the place has been characterized as a butcher 
 shop." 20 As another more or less typical illustration, a "hinge 
 factory" may be mentioned where "overtime" work until half- 
 past eight is demanded almost throughout the year, there 
 being no regular alternation of busy and slack seasons, but change 
 according to orders. 21 This irregularity is peculiarly true of the 
 laundries, where in the latter part of the week "overtime" often 
 lasts till eleven o'clock at night and later. 22 
 
 In regard to railway employees, Crystal Eastman quotes a 
 yard-master as follows : 
 
 Yardmen now usually work twelve hours, but when the yards are 
 pressed, they often work the brakemen the sixteen-hour limit. And when 
 a man works sixteen hours at a stretch, it often means that he has been 
 awake eighteen or twenty hours, because there is a rule that a man must be 
 called two and a half hours before he goes on duty. 2 * 
 
 In the steel industry, the working day is usually twelve hours. 
 A typical steel- worker says : 
 
 I've been twenty years at the furnaces and have been working a twelve- 
 hour day all that time, seven days in the week We work that way 
 
 for two weeks and then we work the long turn and change to the night shift. 
 The long run is when we go on at seven Sunday morning and work through 
 the whole twenty-four hours up to Monday morning. 8 * 
 
 John A. Fitch says that in 1907 he could find only about 120 
 eight-hour men among the 17,000 employees in the three largest 
 plants of the Carnegie Steel Company in Allegheny County a 
 
 " Ibid., 53. * Ibid., 233. " Ibid., 225. 
 
 " See Clark and Wyatt, "Women Laundry Workers in New York," McClure's, XXXVI, 
 401-13- 
 
 23 Crystal Eastman, op. cit., 33. 
 
 34 John A. Fitch, The Steel-Workers (Charities Pub. Com., 1911), 170. 
 
24 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 trifle less than three- fourths of i per cent ; "the prevailing work- 
 day is twelve hours for steel-workers." But the machinists being 
 also repair men are sometimes obliged to work much longer, occa- 
 sionally "a continuous twenty-four-hour period, while sometimes 
 the men work thirty-four hours or longer without rest." 25 
 
 Under normal conditions, fatigue would be overcome by ade- 
 quate periods of rest, but in modern industry the workman is 
 often denied the satisfaction of the physiological demands of 
 fatigue. The human organism is so constructed that on rare 
 occasions great reserve powers can be called out. Modern in- 
 dustrial labor is such that the reserve forces are called out daily. 
 Mental strain and muscular fatigue are phases of the general 
 fatigue process which develops with accumulative force, not 
 only in the course of a day-period, but week by week. Jo- 
 teyko says that it appears certain that fatigue accumulates "s'ac- 
 cumule progressivement" in the organism. 26 "Fatigue is 
 viciously progressive," says Dr. Favill. 27 The actual structural 
 changes, the impairment of the nutritive processes, the accumu- 
 lation of poisonous products when taken together make up "an 
 overwhelming incubus which no organism can long survive." 28 
 
 Fatigue sometimes starts a vicious circle which leads to the 
 craving of and indulgence in means for deadening fatigue. 
 Liquor may drive away temporarily the fatigue sensations, but 
 in the end it will leave the workman weaker, more subject ,to 
 trembling, to uncertain muscular control, and to injury. 
 
 Where fatigue is not balanced by adequate rest and nourish- 
 ment, a deficitj-emains which is added to daily, which accumu- 
 lates little by little; and the workman suffers increased suscepti- 
 bility to accident. When the workman's strength becomes 
 debilitated through overwork, he becomes incapable of atten- 
 tion, 29 and defenseless against accident. 
 
 Present-day operation of dangerous machinery finally re- 
 solves itself into a competition of sensitive human nerves and 
 
 "Op. tit., 174. 
 
 * J. Joteyko, "Participation des centres nerveux dans les phenomenes de fatigue muscu- 
 laire," L'annee Psych., VII, 166. 
 
 >r H. B. Favill, "The Toxin of Fatigue," Survey, XXIV, 772. " Ibid. 
 
 19 Th. Ribot, "The Psychology of Attention," Open Court (1896), 99. 
 
EMORY S. BOGARDUS 25 
 
 muscles against relentless and insensitive iron. 30 The greater 
 the number of hours that machinery must be operated per day, 
 the feebler and more uncertain become the human forces that 
 guide it. To the machine, time is nothing; to the working man 
 and woman, each hour that passes beyond a certain limit offers 
 increasing opportunity of injury and possibility of death. 
 
 While monotony, speed, unrelaxed tension, together with long 
 hours, appear to be the leading general causes of industrial fatigue 
 and hence of many accidents, it is proposed next to determine if 
 possible the modus operandi of these general causes in bringing 
 about accidents. In other words, what are the concrete, imme- 
 diate conditions preceding accidents? 
 
 The writer has had access to the accident records of the state 
 of Illinois for the year ipio. 31 These records refer to accidents 
 which necessitated that the injured lay off from work fifteen days 
 or over, and they apply to the various manufacturing industries, 
 the steel industry, and to many small plants and factories in 
 Illinois. Of the total number of accident reports some over 
 3,000 which were examined, 2,678 applied to non- fatal cases 
 and gave a fairly accurate description of what happened preced- 
 ing the given accidents. The remaining 4OO-odd reports either 
 omitted a description of the immediate cause or else gave it so 
 inaccurately as to throw doubt on its value for this analysis. 
 
 The accident descriptions which apparently are accurate fall 
 into two general classes. Class A includes the accidents where 
 the immediate cause was evidently beyond the control of the 
 injured due to the breaking of machinery, to bursting of 
 boilers, to chips of steel flying in the air. Typical statements 
 illustrating this general class of accidents, as taken from the 
 accident reports, are subjoined: 
 
 Scaffold collapsed. 
 
 Bolster flew out from under steam hammer. 
 
 Chip in eye. 
 
 Gas exploded. 
 
 Hot steam blew in eye. 
 
 J *T. Oliver, Dangerous Trades, 117. 
 
 31 1 wish to acknowledge the courtesies shown me by Edgar T. Davies and his assistants in 
 the office of State Factory Inspection (Chicago). 
 
26 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 Flying nail struck eye. 
 
 Struck in the face by piece of iron .... due to pulley breaking. 
 
 Hot scale blew into eye. 
 
 It is beyond doubt that in the cases represented by Class A, per- 
 fect subjective control preceding the given accidents would not 
 have made escape possible. 
 
 Class B represents those accidents in which loss of control, 
 varying from failure to make fine co-ordinations on to gross and 
 bungling co-ordinations and to absence of movements which 
 might have prevented injury, appears to have been a factor. 
 Class B is illustrated by the following typical descriptions : 
 
 Did not get her hand away soon enough and thumb was caught between 
 billets. 
 
 Placed his finger too close to the cutter in putting in a piece of work. 
 
 Got his fingers under the die when it came down. 
 
 Caught hand under punch. 
 
 In some manner he got the small finger of right hand against the saw 
 while the same was in motion. 
 
 Did not get his hand out of the way in time and his fingers were caught 
 between plunger and edge of socket. 
 
 His hand slipped over the guard and caught in the knife. 
 
 His fingers went under the die when he accidentally tripped the press. 
 
 Caught his fingers in the die. 
 
 The injured accidentally placed his finger too close to the cutter in put- 
 ting in a piece of work. 
 
 Automatically placed foot on treadle when tips of fingers were under die. 
 
 Hand slipped on to rip-saw. 
 
 Caught hands in knives. 
 
 Caught fingers between press and die. 
 
 Caught fingers between head of die and material. 
 
 Caught fingers in jointer while operating same. 
 
 Caught thumb between sheet metal and die. 
 
 Her finger slipped into the gear of her machine. 
 
 Of the 2,678 accident records which gave a fairly good de- 
 scription of what occurred immediately preceding the accidents, 
 twelve records were of doubtful analysis. Four hundred and 
 sixty-three cases or 17.2 per cent belonged to Class B. Of the 
 fatal-accident reports studied the number is too small to be of 
 much value. Twenty fatal accidents or 37.8 per cent were of 
 Class A; and forty-one or 62.1 per cent belonged to Class B. 
 
EMORY S. BOGARDUS 
 
 Table I shows that a large percentage of non- fatal accidents is 
 immediately preceded by muscular inaccuracies. In all cases of 
 Class B, it is conceivable that if the injured had had perfect and 
 ready control over muscular movements he would not have suf- 
 fered accident. 
 
 TABLE I 
 
 INDUSTRIAL ACCIDENTS CLASSIFIED 
 
 Year 1910 
 
 Doubtful 
 
 Class A 
 
 Class B 
 
 Total 
 
 Number 
 
 12 
 
 4.63 
 
 2,203 
 
 2,678 
 
 Percentage 
 
 o 4 
 
 17. 2 
 
 82.2 
 
 IOO 
 
 
 
 
 
 
 In Section II it has been shown that the developing subjective 
 fatigue processes inevitably result in increasing muscular inac- 
 curacy; in the preceding paragraphs of this section it has been 
 y further shown that monotony, speed, mental strain in connection 
 with long hours hasten the fatigue processes and hence greatly 
 increase the loss of muscular control. In this section it is main- 
 tained that to the extent that fatigue is a primary cause of mus- 
 cular inaccuracies, 82.2 per cent of the 2,678 accidents studied 
 involved fatigue as a causal factor. 
 
 This proposition is illuminated by the fact that "the swift 
 machinery of modern industry requires the attendants to push 
 and guide the material in close proximity to merciless cutting 
 tools." 32 In Chicago the writer found twenty types of ma- 
 chines in connection with which the operatives were working so 
 close to revolving saws, knives, drills, rollers, or at machines 
 of the press and die type that the misplacement of the hand a 
 fraction of an inch meant mutilation. The three accidents which 
 the writer witnessed were exactly of this nature two at 
 soldering machines and one at a press and drill in each 
 case a hand was misplaced a fraction of an inch and came into 
 contact with dangerous parts of the respective machines. 
 
 At mangles, too, the danger is grave. What the girls call "millionaire 
 work" work that has to come out straight in contrast with "board- 
 ing-house" work, must be shoved up to tvithin a quarter of an inch of 
 the cylinder. Fingers once caught in such mangles are crushed. Consider 
 
 33 C. R. Henderson, op. cit., World To-Day, XIX, 972. 
 
28 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 in connection with these two points the high rate of speed at which the 
 girls feed the work into the machine, and the precarious character of their 
 work will be realized. 38 
 
 From these facts it is evident that the slight slips and mis- 
 takes which every person makes are exactly the phenomena which 
 precede many serious accidents when they occur in dangerous 
 occupations. "When a cook drops a cup, the loss is a few cents; 
 when a structural iron-worker is guilty of no greater inattention, 
 he may lose his life." 34 
 
 The thesis of this section has been confirmed by a report 
 prepared by the Bureau of Labor which is not off the press at 
 this writing (April i, 1911). The following excerpt is taken 
 from proof sheets : 
 
 It (the fatigue process) gradually upsets those nice adjustments of 
 the living organism upon which depend efficient labor and the safety of the 
 worker. The margin of safety in modern industry is small. It is measured 
 too frequently by fractions of an inch. Reduce the alertness and the exact- 
 ness with which the body responds to the necessities of its labor, and by just 
 so much have you increased the liability that the hand will be misplaced that 
 fraction which means mutilation* 
 
 Thus slight deviations entail serious consequences and result 
 in industrial accidents. "The exhausted workman no longer 
 has full control over his muscles. His results are less exact, 
 danger by accident increases/' 36 Even the skilled laborer does 
 not work as regularly as the machine. His ability to make ac- 
 curate movements shows regularly returning shrinkings as a 
 result of the activity of the neural-muscular factors. 37 This phase 
 of the fatigue problem has been summed up by Felix Arnold : 
 
 Concentrated activity, especially when it involves motor control, usually 
 results in fatigue. There arises .... increased slowness of response. Effi- 
 ciency of attention begins to decline In simple reactions, the reaction 
 
 time becomes longer. Objects in the field of attention persist for a less time 
 in the center of control. On the subjective side, fatigue is felt as weariness, 
 disinclination to persistent effort, sensation of strain in the muscles, lack of 
 interest in situations which normally are of an impelling nature, and some- 
 
 Clark and Wyatt, McClure's, XXXVI, 402. 
 
 ** Bureau of Labor and Industrial Statistics (Wisconsin), 13th Bien. Report, Part I, p. 4. 
 
 " Senate Document No. 645, v. n, p. 42. 
 
 36 H. Herkner, Handworterb. d. Staatswissensch. (Jena, 1909), I, 1215. 
 
 " E. Roth, 14. Intern. Kongr.f. Hyg. u. Demog., II, 611. 
 
EMORY S. BOGARDUS 29 
 
 times as pain in the parts of the body affected. On the objective side fatigue 
 is manifested by a general slackness and listlessness of the body posture, by 
 relaxed fingers, and by asymmetrical and fidgety movements. Co-ordina- 
 tions become more bungling, incorrect, and for finer control often impossible" 
 
 If men and women subject to industrial overstrain are work- 
 ing at or near rapidly revolving knives or saws, are operating 
 punches, presses, or drills at a furious rate of speed, their chances 
 are good of being counted among the annual list (in the United 
 States) of 30,000 killed and 500,000 injured in industry. 39 
 
 The law of fatigue as related to accidents and given at the 
 close of Section II may be restated in the light of the facts of 
 this section as follows: The irregularly increasing muscular in- 
 accuracy which accompanies work results in correlatively in- 
 creasing chances of accident. 
 
 It is proposed to test this law by further facts. In the fol- 
 lowing section it will be attempted to verify further, if possible, 
 the causal relationship existing between fatigue, decreasing mus- 
 cular control, and accidents, by means of several series of con- 
 trolled experiments in which various industrial conditions are 
 more or less closely simulated. 
 
 IV. SOME CONTROLLED EXPERIMENTS 
 
 (From the Psychological Laboratory of the University of Chicago)* 
 
 Section II set forth the fact that continued work is accom- 
 panied by increasing muscular inaccuracy. In Section III it 
 was shown that these muscular inaccuracies are the immediate 
 phenomena preceding a large proportion of accidents. In order 
 to determine more exactly the nature of the muscular inac- 
 curacies which increasingly accompany continued work and 
 
 ** Felix Arnold, Attention and Interest (Macmillan, 1910), 153. 
 
 " J. B. Andrews, "A Clinic for Industrial Diseases," Survey, XXV, 269. 
 
 1 Preliminary to these experiments, the writer conducted two series of experiments on the 
 typewriter. The striking of a typewriter key requires a definite muscular co-ordination. All 
 variations of one-half inch and over from the correct muscle movement appear as errors on the 
 typewritten pages. These faulty co-ordinations are similar in general nature to the muscular 
 inaccuracies which precede many industrial accidents. The results of the typewriter experi- 
 ments indicated clearly an irregular but marked increase in the number of muscular errors 
 occurring during a given work-period. This increasing inaccuracy was accompanied by symp- 
 toms of increasing fatigue. But it will be observed that in experiments on the typewriter, the 
 power which runs the typewriter is intrinsic; that is, the subject or operator by his own voli- 
 tion must keep the typewriter in motion. It appeared that these experiments would have 
 
30 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 which result in increasing danger of accident, a type of machine 
 for experimental purposes was designed which in its operation 
 would combine the factors most common to industrial conditions, 
 namely, monotony, speed, mental strain and which at the same 
 time would permit a computation of the muscular inaccuracies 
 resulting from operating it. 2 
 
 Figs, i and 2, will give an idea of the apparatus used. The 
 part of the machine designated x in Fig. i appears in enlarged 
 form in Fig. 2. The letters a, b, c, d represent thin brass plates 
 so set in the top of the table that their inner lines form a square 
 of one-inch dimensions. They do not come in contact with each 
 other; their upper surfaces are practically on a level with the 
 upper surface of the table. The letters a', b', c' , d' designate 
 another set of brass strips whose inner lines are three-sixteenths 
 of an inch from the inner lines of a, b, c, d, respectively. The 
 subject was given wooden inch cubes, one side of each being 
 covered with a thin brass plate. If the block was accurately 
 placed its outer edges brass side down would exactly coincide 
 with the inner lines of a, b } c, d. However, the outer edges of 
 the brass base could extend over the lines of a, b, c, d practically 
 three-sixteenths of an inch in any direction and the placement 
 would still be counted as accurate. But the brass strips were so 
 electrically wired that a and a', b and b' ' , etc., represented the 
 termini of respective circuits. Hence if the brass base of a block 
 for instance, was misplaced to the extent that one of its sides 
 extended over a! , as represented by the dotted line r, an electrical 
 circuit was established and an error was recorded on an endless 
 sheet of smoked paper carried by two slowly revolving Scripture 
 drums, arranged after the manner of Yoakum. 3 If the block 
 
 greater value if conducted on a machine which was run by external power, e.g., by an electric 
 motor. In this case the operator would be required to keep up with the pace set by the machine, 
 and not set his own pace. 
 
 It was this problem which I took to Professor James R. Angell, to whom I am indebted 
 for making possible the experiments described in this section, for designing a considerable 
 portion of the apparatus, and for many stimulating suggestions. The apparatus which is 
 described in the following pages was built only after a special study had been made of dangerous 
 machines in industry. It was designed especially to incorporate as many as possible of the 
 general features of the machines used in the dangerous trades. 
 
 1 For the purposes of this chapter, these experiments have been presented from a socio- 
 logical point of view. Much material is at hand for a psychological discussion. 
 
 J C. S. Yoakum, An Experimental Study of Fatigue, 54. 
 
EMORY S. BOGARDUS 
 
 was misplaced as represented by the dotted line /, the circuits 
 represented by the termini b and b' ' , and d and d' were closed 
 respectively and two errors were recorded on the smoked paper 
 
 FIG. i 
 
 by corresponding markers. It was not possible to close more 
 than two circuits and hence make more than two errors by a 
 single misplacement. It will be noted that the inner lines of a' 
 
32 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 and d f , and of b' and c' are separated by one and three-eighths 
 inches, respectively, so that a leeway of three-eighths of an inch 
 in either direction was given. 
 
 A revolving pulley O (Fig. i), driven by power obtained 
 through a speed-reducer from a motor, carried a double arm, m 
 and m 1 '. Both m and m r carried shields s and s' t respectively, 
 set at an angle such that when the pulley revolved, the blocks 
 being set on the square would be brushed off to the left and 
 toward the subject who was seated facing x. Each of the 
 shields s and s' were of brass (as were the arms m and m' and 
 the pulley) and each carried a small brush of fine brass wire 
 attached to the lower inner corner. As the shield brushed off a 
 block at x the small wire brush passed over a brass knob k and 
 closed an electrical circuit, which occurrence was recorded by a 
 fifth marker on the smoked paper mentioned in the preceding 
 paragraph. Reference to the smoked paper showed the nature 
 of errors, i.e., the direction in which the misplacement occurred, 
 the number of errors, and their occurrence in relation to the 
 time-element. An observation method was devised which served 
 as a check on the record carried by the smoked paper. Because 
 of a great variety of phenomena which happened in connection 
 with the placement of the blocks and which the registering 
 apparatus could not be made to record, the observation method 
 proved more accurate and satisfactory and was finally adopted. 
 
 Before each test the subject was given as much time as he 
 wished for practice. He did not know exactly when his test- 
 period began nor when it was likely to close except that he 
 knew that it would not extend over twenty minutes. By this 
 method the factors of "warming up," of the nervousness fre- 
 quently attendant on beginning a piece of work, and of the "final 
 spurt" were almost entirely eliminated. The actual test-period 
 was made fifteen minutes long in all cases, although none of the 
 subjects knew this fact fifteen minutes being the length of time 
 determined upon as sufficient to indicate many of the character- 
 istics of fatigue, to show the tendency of these characteristics, 
 and to bring out important points regarding the nature of mus- 
 cular inaccuracies. The tests were made on successive days and 
 
EMORY S. BOGARDUS 33 
 
 at the same hour each day for the given subject as far as possible; 
 any variations were noted. A record of the subject's general 
 physical condition at the beginning of each test was kept and 
 also of the subject's introspections at the close of the daily trial. 
 
 The following method of evaluation of errors was adopted as 
 being the most satisfactory. If the block was misplaced to the 
 left, for example, so as to establish the connection represented 
 by the termini aa r (illustrated by the dotted square r, Fig. 2), 
 one error was counted ; if, as shown by the dotted square /, the 
 block was misplaced so as to make the connections bb' and dd r , 
 two errors were recorded. If either hand of the subject was hit 
 by the revolving shields s and s' f three errors were counted 
 such an occurrence being a gross inaccuracy. Failure to put in 
 a block being the omission of a whole muscular co-ordination 
 was evaluated at five errors. Other types of maladjustments 
 occurred occasionally and were evaluated on the above basis. 
 
 It may be well to note that in these experiments an essential 
 feature of the method is that stimuli were provided of the so- 
 called extrinsic nature. 4 The machine being driven by electricity 
 set the pace and the subject was required to keep up. To the 
 observer these tests appeared as a real contest between human 
 muscle and sensitive nerves, and the machine, insensible and inde- 
 fatigable. The machine regularly worked on and on; the subject 
 worked irregularly, with increasing tendency to fall behind. 
 
 Although in these experiments no saws, knives, or drills were 
 present and hence gross muscular inaccuracies did not mean 
 actual mutilation of the subject's hands, this fact appeared to be 
 adequately balanced by three other factors, (a) Throughout the 
 experiments each subject clearly manifested an instinctive dread 
 of getting hit by the revolving shield even in the final experi- 
 ments, the subject would instinctively jerk back his hand when- 
 ever he became conscious that his hand was likely to be hit. (&) 
 Throughout the experiments the records of each subject were 
 posted and a healthy spirit of competition was maintained which 
 assisted greatly in keeping up a maximum efficiency, (c) In 
 particular, the graduated system of evaluating inaccurate co- 
 ordinations served continually in keeping down the number of 
 
 4 W. H. R. Rivers, The Influence of Alcohol, etc., on Fatigue, 12. 
 
34 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 gross inaccuracies. The writer believes that these factors when 
 taken together served to maintain a degree of carefulness in 
 operating this experimental machine comparable to that mani- 
 fested by the average worker in the dangerous trades, who in- 
 evitably becomes inured to the danger of working close to 
 revolving knives, saws, drills, etc. 
 
 Eleven subjects participated in these experiments. 5 Br., Hy., 
 Pr., Sp., Sw., and Wr. were men; Ch., Fr., Hys., My., and Wd. 
 were women. This list included trained psychologists who had 
 worked at reaction-time experiments, at co-ordination of hand 
 and eye movements, at general fatigue experiments. Three of 
 the subjects had taken part in the prolonged series of fatigue 
 experiments conducted by Yoakum. One of the subjects had 
 worked in a screw room; another, as an operator in a telephone 
 exchange. In view of the considerable amount of practice which 
 was given in these experiments the results did not show any 
 particular effects of the previous training of the subjects. This 
 point will be discussed later. Further details regarding methods 
 will be given when the various groups of experiments are de- 
 scribed. 
 
 The first group of experiments was designed to get a maxi- 
 mum of simplicity of operation, of monotony, of speed, and of 
 mental strain or unrelaxed tension. The rate was such as to 
 require that a block be set on the square x (Figs, i and 2) once 
 a second or sixty times per minute. Two blocks were used. The 
 cycle of a single operation may be described as follows : (a) 
 stopping block i with the left hand when brushed off the square 
 x by the machine, and putting block 2 on the square x with the 
 right hand; (b) passing block i over from the left hand to the 
 right hand; (c) placing block i on the square with the right hand 
 while the left hand stopped block 2 ; and so on. The monotony, 
 speed, and unrelaxed tension of this process is obvious. 
 
 Eight subjectsi four men, Hy., Pr., Sp., Sw., and four 
 women, Ch., Fr., Hys., and Wd. worked in Group I. Each 
 subject was given several practice trials, covering two or three 
 weeks, until the maximum efficiency was obtained, as far as could 
 
 * The writer wishes to express his deep obligation to the persons who willingly gave of their 
 time and strength that this investigation might be furthered. 
 
EMORY S. BOGARDUS 
 
 35 
 
 be judged by the daily records of errors. The tests were then 
 continued until six to ten normal records were obtained for each 
 subject. By the use of volitional power and highly concentrated 
 attention, and as a result of a strong spirit of rivalry, the subject 
 tried in each test to make no errors or to keep the errors within 
 minimum limits. 
 
 Among other things, the errors of each subject were tabulated 
 according to their occurrence in the first or in the second half 
 of the given test periods. 6 The tabulated figures for each sub- 
 ject were added together and the average daily number of errors 
 for the first and second halves of the test periods was obtained. 
 The results appear in Table II. 
 
 TABLE II 
 MUSCULAR INACCURACIES (GROUP I) 
 
 Subject 
 
 Average Num- 
 ber of Errors, 
 First Half 
 
 Average Num- 
 ber of Errors, 
 Second Half 
 
 Average Total 
 Number of 
 Errors 
 
 Ch. . 
 
 3.OO 
 
 6 oo 
 
 Q.OO 
 
 Fr 
 
 6.16 
 
 iq.Si 
 
 21 .00 
 
 Hy 
 
 6.66 
 
 12. OO 
 
 18.66 
 
 Hys 
 Pr 
 
 S.i6 
 
 2 .OO 
 
 13.00 
 5.83 
 
 18.16 
 7.83 
 
 Sp. . 
 
 4. <;o 
 
 5.83 
 
 10. w 
 
 Sw.. 
 
 1.83 
 
 4.OO 
 
 5.83 
 
 Wd 
 
 1.66 
 
 3.83 
 
 c .40 
 
 
 
 
 
 Total 
 
 30-97 
 
 66.32 
 
 97.29 
 
 General average . . . 
 
 3-87 
 
 8.29 
 
 12. 16 
 
 From Table II it will be observed that the average daily num- 
 ber of errors for all subjects was 3.87 for the first half of the 
 test periods and 8.29 for the second half. In other words, 31.82 
 per cent of the errors occurred in the first half of the test periods 
 and 68.17 per cent in the last half. As determined by the intro- 
 spections, the immediate cause of the distribution of muscular 
 inaccuracies in this fashion is to be found largely in the irregu- 
 larly decreasing effectiveness of the attentive processes. In par- 
 
 6 In analyzing the results of these experiments, a large number of tables have been made. 
 Only those have been selected for use here which best present the general results. It is difficult 
 to avoid the omission of some classifications of data which might prove helpful. 
 
36 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 ticular, such factors entered as rise of feelings of effort, of 
 strains, of fatigue in the muscles of the eyes, arms, back, hands, 
 legs, abdomen, etc. In many of the tests the subjects experienced 
 a growing uncertainty of muscular control over the hands. 
 
 Whatever the cause, the most significant result of this group 
 of experiments was the fact that the subjects were not able to 
 maintain a steady degree of volitional attention even though they 
 knew that the test would cover a short period of not over twenty 
 minutes. During these tests the subjective processes broke down, 
 in spite of continued efforts of the subjects to the contrary, to 
 the extent of permitting practically twice as many errors to occur 
 in the second half as in the first half of the work period. Some 
 of the subjects, whose work in this group of experiments is 
 fairly typical, are working for much longer test periods. The 
 strain on the individual caused by the greater length of the work 
 period is compensated by giving him a slower rate of speed. 
 While full results are not yet at hand, the indications are that 
 when the longer period is divided into two equal periods for 
 purposes of comparisons, the relation between the number of 
 errors occurring during the first half and during the second half 
 of such a period is almost a duplicate of the results shown in 
 Table II. In other words, when the operation of the experi- 
 mental machine is made less rigorous and continued for greater 
 lengths of time, so that fatigue does not develop in fifteen 
 minutes (as in the experiments already described), but in the 
 given increased period of time, it may be assumed that the results 
 in Table II would not suffer material change. 
 
 Tables II and III illustrate the law of fatigue as given at the 
 close of Section II, that continued work is accompanied by in- 
 creasing muscular inaccuracy. Granted that the general results 
 of this group of experiments would not have been essentially 
 changed if a lower rate of speed had been substituted for a high 
 rate and a longer period of time substituted for a short period- 
 two substitutions which may be considered as counterbalancing 
 each other in a large measure then the following conclusion 
 may be given: If the subjects in this series of experiments had 
 been operating dangerous machines where slight misplacements 
 
EMORY S. BOGARDUS 37 
 
 mean mutilation, the danger of accidents would have been far 
 greater (if not twice as great) in the latter half than in the first 
 half of a given work period. 
 
 In Section II the point was emphasized that the increase in 
 muscular inaccuracy which accompanies continued work depends 
 on the rate of work. That is to say, if the operative of a dan- 
 gerous machine should be "speeded up," his danger of suffering 
 accident would be thereby increased; and that increased danger 
 would persist as long as the increase in rate of work remained a 
 "speeded-up" operation for the given operative. According to 
 the law given at the close of Section II, an increase in speed will 
 hasten the fatigue processes, the development of muscular v ; nac- 
 curacies, and hence the chances of accident. 
 
 In testing this point the apparatus used in the preceding series 
 was slightly modified. A pipe p and a square box q containing 
 a dozen inch cubes were added to the apparatus ( see Fig. i ) . By 
 this time the observation method had been so satisfactorily de- 
 veloped that the brass plates on one side of the blocks were taken 
 off and the subject permitted to place the blocks with any side 
 down. The cycle of operations consisted in catching the block 
 with the left hand as it was brushed off the square x by the 
 machine and of dropping it in the opening of the spout p. In 
 the mean time the right hand had to pick out another of the 
 blocks from box q and place it accurately on the square x. 
 
 The speed was made one-half that of the preceding series, or 
 30 blocks per minute. This was a rate which seemed slow or 
 moderate to most of the subjects and errors appeared to occur 
 more as a result of chance than from any other cause. As far 
 as the speed was concerned, there was no excuse for errors. 
 Tests were made daily at this rate until a series of records was 
 secured sufficient to serve as a basis of comparison with the 
 results obtained from speeding up. Then the rate was increased 
 from 30 to 37^ blocks per minute. On the day that test i was 
 made at the faster rate, and preceding the test, the subject was 
 given all the time that he wished for practice. Tests at the 37J4 
 rate were continued for twelve days for all subjects. Then a 
 faster rate of 45 blocks per minute was offered. Table III gives 
 
RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 the number of errors made by each subject during the series of 
 trials at the three rates of speed. 
 
 TABLE III 
 
 MUSCULAR INACCURACIES (GROUP II) 
 
 Rate 
 
 No. of 
 Trials 
 
 Br. 
 
 Fr. 
 
 Hy. 
 
 Hys. 
 
 My. 
 
 Pr. 
 
 Wd. 
 
 Wr. 
 
 Total 
 
 
 I 
 
 I 
 
 2 
 
 2 
 
 4 
 
 4 
 
 o 
 
 6 
 
 16 
 
 35 
 
 30 
 
 2 
 
 I 
 
 6 
 
 8 
 
 2 
 
 5 
 
 i 
 
 
 
 4 
 
 27 
 
 
 3 
 
 2 
 
 3 
 
 o 
 
 O 
 
 o 
 
 12 
 
 6 
 
 9 
 
 32 
 
 
 4 
 
 O 
 
 i 
 
 6 
 
 I 
 
 3 
 
 2 
 
 i 
 
 i 
 
 15 
 
 
 i 
 
 25 
 
 92 
 
 39 
 
 127 
 
 14 
 
 39 
 
 2 
 
 44 
 
 387 
 
 
 2 
 
 17 
 
 57 
 
 IS 
 
 3 1 
 
 IO 
 
 54 
 
 3 
 
 23 
 
 212 
 
 
 3 
 
 21 
 
 15 
 
 13 
 
 18 
 
 16 
 
 15 
 
 7 
 
 39 
 
 144 
 
 
 4 
 
 IO 
 
 5 
 
 29 
 
 61 
 
 14 
 
 7 
 
 3 
 
 38 
 
 l6 7 
 
 
 5 
 
 9 
 
 6 
 
 18 
 
 5 
 
 IO 
 
 44 
 
 3 
 
 26 
 
 117 
 
 
 6 
 
 9 
 
 23 
 
 3 
 
 20 
 
 ii 
 
 23 
 
 i 
 
 18 
 
 1x8 
 
 37^ < 
 
 
 
 
 
 
 
 
 
 
 
 
 7 
 
 4 
 
 12 
 
 4 
 
 i 
 
 2 
 
 7 
 
 7 
 
 14 
 
 51 
 
 
 8 
 
 3 
 
 29 
 
 2 
 
 4 
 
 7 
 
 17 
 
 3 
 
 6 
 
 81 
 
 
 9 
 
 3 
 
 23 
 
 I 
 
 3i 
 
 4 
 
 34 
 
 i 
 
 6 
 
 103 
 
 
 10 
 
 3 
 
 I 
 
 7 
 
 6 
 
 i 
 
 2 
 
 6 
 
 7 
 
 33 
 
 
 ii 
 
 3 
 
 22 
 
 22 
 
 4 
 
 o 
 
 8 
 
 7 
 
 4 
 
 70 
 
 
 12 
 
 o 
 
 9 
 
 7 
 
 7 
 
 o 
 
 7 
 
 7 
 
 33 
 
 70 
 
 
 I 
 
 48 
 
 128 
 
 52 
 
 148 
 
 65 
 
 "5 
 
 70 
 
 325 
 
 943 
 
 
 2 
 
 101 
 
 108 
 
 18 
 
 166 
 
 56 
 
 134 
 
 56 
 
 88 
 
 736 
 
 4.C, . 
 
 
 123 
 
 117 
 
 22 
 
 7i 
 
 2 A 
 
 IO4. 
 
 64 
 
 202 
 
 7^1 
 
 
 4 
 
 * 
 
 57 
 
 * * / 
 
 182 
 
 o^ 
 75 
 
 / o 
 21 
 
 OT- 
 
 *3 
 
 xwif. 
 
 102 
 
 V *T 
 
 26 
 
 108 
 
 / o 
 
 584 
 
 
 5 
 
 46 
 
 79 
 
 82 
 
 134 
 
 15 
 
 118 
 
 16 
 
 256 
 
 74 6 
 
 Although the first trials at the 37^ rate in the case of each 
 subject were preceded by a practice period, the effect of speeding 
 up from a 30 to a 37^ rate on muscular inaccuracy is marked. 
 As indicated by Table III, the increase varies considerably from 
 the case of Wd. to that of Hys., where the increase in number of 
 inaccuracies is from i to 127. For the first six trials at the 37 J4 
 rate the process was clearly a speeded-up one for all the subjects 
 excepting Wd. ; a decrease in errors is also characteristic. For 
 the last six trials at the 37^ rate, the totals of errors indicate 
 that no further decrease in inaccuracies would have resulted if 
 the series at this rate had been continued. The introspections 
 given by the subjects bear out this conclusion. The totals for 
 these last six trials also indicate that the 37^2 rate had become 
 a much less speeded-up process than for the first six trials at 
 
EMORY S. BOGARDUS 
 
 39 
 
 that rate, but that it still remained a speeded-up process when 
 compared with the records for the 30 rate. 
 
 Table III shows that the introduction of the 45 rate (al- 
 though the first trials were again preceded by a practice period) 
 was accompanied by a large increase in the number of errors. 
 Table IV is prepared from Table III and indicates the relative 
 percentage of errors occurring in the first and second half of the 
 trials at the 30 rate, for the first six and for the second six trials 
 at the 37J4 rate, and for the 45 rate, for each subject; at the 
 30 or slow rate where errors were not due to speed, but appar- 
 ently to chance, the average percentages of errors indicate that 
 practically the same number of inaccuracies occurred in the first 
 half as in the second half of the given work period the ratio 
 being 50.0 to 49.8. 
 
 But when the rate was increased to 37^ blocks per minute 
 there occurred not only a large increase in the actual number of 
 errors, but, as will be seen by looking at Table IV, a large pro- 
 
 TABLE IV 
 PERCENTAGE OF ERRORS (FROM TABLE III) 
 
 SUBJECT 
 
 30 RATE 
 
 37* RATE 
 (FIRST Six TRIALS) 
 
 37* RATE 
 
 (SECOND Six 
 TRIALS) 
 
 4SRATE 
 
 First 
 Half 
 
 Second 
 Half 
 
 First 
 Half 
 
 Second 
 Half 
 
 First 
 Half 
 
 Second 
 Half 
 
 First 
 Half 
 
 Second 
 Half 
 
 Br.. 
 
 75-0 
 33.3 
 50.0 
 25.0 
 66.6 
 73-3 
 30.7 
 46.6 
 
 25.0 
 66.6 
 50.0 
 75.0 
 33-3 
 26.6 
 69.2 
 53-3 
 
 49-4 
 49-4 
 37-6 
 42.3 
 24.0 
 19.1 
 26.3 
 3i-5 
 
 SO.S 
 62.8 
 62.3 
 57-6 
 76.0 
 80.8 
 73.6 
 68.4 
 
 43-7 
 32.0 
 60.4 
 39-6 
 35-7 
 4L3 
 29.0 
 
 50-7 
 
 56.2 
 67.8 
 39.5 
 60.3 
 64.2 
 58.6 
 70.9 
 49.2 
 
 33.6 
 29.9 
 38.4 
 36.7 
 44-5 
 34.8 
 26.9 
 40.9 
 
 66.3 
 70.0 
 6l. S 
 63.2 
 SS.4 
 6 S .I 
 73-0 
 59-0 
 
 Fr 
 
 Hy 
 
 Hys 
 
 My 
 
 ^"y 
 Pr. 
 
 Wd 
 
 Wr . 
 
 Average 
 
 50.0 
 
 49-8 
 
 33-4 
 
 66.5 
 
 41-5 
 
 58.3 
 
 35.7 
 
 64.2 
 
 
 portion of the inaccuracies occurred in the second half of the 
 given trials. The ratio of errors between the first and second 
 halves of the first six trials at the 37^ rate was 33.4 to 66.5. For 
 the second six trials at the 37K rate when this rate no longer in- 
 volved as speeded-up operations as during the first six tests, 
 because of skill resulting from practice, the percentage of inac- 
 
40 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 curacies fell, the ratio being 41.5 to 58.8. When the rate was 
 increased to 45 blocks per minute, the process again became a 
 speeded-up one and the percentage of inaccuracies in the last 
 half of the trial periods again rose this time to 64.2 per cent. 
 The ratio was 35.7 to 64.2. 
 
 The noteworthy fact in these experiments is that as soon as 
 the work was speeded up from the 30 to the 37^ rate or from 
 the 37^2 to the 45 rate, the larger part of the increase of errors 
 took place in the latter half of the given work periods. These in- 
 creases clearly show the effect of fatigue on muscular inaccu- 
 racies. This conclusion, based on the objective records, is corrobo- 
 rated by the introspections given by the subjects. While operat- 
 ing the machine at the speeded-up rates, all the subjects com- 
 plained of sensations of fatigue during the second half of the 
 work periods, ranging from distinct strains in the muscles of the 
 eyes, arms, and hands to temporary paralysis of the right arm 
 (Wr., in whose case the right arm co-ordinations broke down 
 completely, and the subject was forced to stop in one test) . Typi- 
 cal introspective reports are subjoined : 
 
 Eye strain felt during last three or four minutes. 
 
 Slammed blocks in toward close of period, because of less certainty of 
 muscle control. 
 
 During last half of period eyes blurred continually. 
 
 Back began to ache about middle of period and continued. 
 
 Conscious of increasing inaccuracy and of increasing feeling of "losing 
 out." 
 
 Greater tendency toward the last to fumble blocks. 
 
 Fumbling increased, caused by developing fatigue in fore-arm, and by 
 lapses of attention. 
 
 Fatigue in arms felt early in trial. 
 
 Fagged all over to keep up the process became a torture. 
 
 Felt pain between shoulders toward the last. 
 
 Almost decided that I couldn't keep it up for full period. 
 
 Compelled to exert increasing volitional power. 
 
 Strain in left arm toward the end of the period. 
 
 Increasingly tended to get behind in muscular movements. 
 
 Boredom of it increased. 
 
 Last few minutes seemed like hours. 
 
 Started well, but fatigue developed in arms, wrists, shoulders. 
 
 Terrible strain developed in right arm. 
 
 Became aware of a general inaccurate feelincc in regard to hands. 
 
EMORY S. BOGARDUS 41 
 
 One or two other points brought out by this group of ex- 
 periments may be mentioned here. Reference to the tables will 
 make clear the fact of marked individual difference in regard to 
 making errors. These variations do not appear to be explained 
 when the subjects are classified on the men and women basis or 
 according to the degree of psychological training, but rather 
 by temperamental differences. Reference to the records of indi- 
 vidual subjects (Table III) shows marked variations from day 
 to day in many cases. The explanation for this fact appears to 
 be found in the varying bodily conditions of the given subject 
 from day to day. The decidedly abnormal conditions were of 
 two kinds either the subject found himself simply "out of 
 form," or else he began the test normally and errors began to 
 increase early and rapidly as a result of late hours, overwork, 
 forms of illness. 
 
 The material presented in this section may be summarized at 
 this point. These experiments indicate that uninterrupted work is 
 accompanied by increasing muscular inaccuracy, and other things 
 being equal, any speeding up in the operation of dangerous ma- 
 chinery means accelerated development of fatigue and of muscular 
 inaccuracy. In other words, fatigue causes muscular inaccuracy. 
 Since, as indicated in Section III of this study, men and women 
 in the hazardous employments are working in close proximity 
 to dangerous tools, and where misplacement of the hands a frac- 
 tion of an inch means mutilation, the material presented in this 
 section may be considered as evidence that fatigue causes acci- 
 dents. The data presented in Section III to the effect that mus- 
 cular inaccuracies are the actual phenomena preceding a large 
 majority of accidents bears out the conclusion that fatigue, mus- 
 cular inaccuracies, and industrial accidents are causally related. 
 In the next section, the hours when accidents occur will be 
 analyzed. 
 
RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 V. ACCIDENT-HOURS 
 
 Reference is made in Section III to a study of accident 
 records (State of Illinois for the year 1910) which has been 
 made by the writer. It will be recalled that of the accident re- 
 ports examined, 2,687 gave a fairly accurate description of what 
 happened preceding the given accidents; and 2,203 or & 2 - 2 P er 
 cent of the 2,687 accidents conceivably might have been avoided 
 if the injured or the fellow-servant, who was the cause of the 
 accident in some cases, had had accurate muscular control. Of 
 the 2,203 accidents which might have been avoided, the time at 
 which 2,162 of these occurred was given. These reports were 
 tabulated according to the hours of the day, and the results 
 appear in Table V. In general, there is ajise in the number of 
 accidents during the forenoon, a decided fall after the noon 
 period of rest, and another rise in the afternoon hours. Further 
 conclusions must be withheld until certain factors are considered. 
 A vital point is to be found, not in the number of accidents per 
 hour, but in the number of accidents per hour during a period 
 when the same number of employees are at work. 
 
 TABLE V 
 
 ACCIDENT-HOURS (ILLINOIS, IQIo) 
 
 Morning 
 
 Accidents 
 
 Afternoon 
 
 Accidents 
 
 7 to 7 : so . 
 
 7O 
 
 I to I ' SO 
 
 ill 
 
 8 to 8 : so . . 
 
 ISO 
 
 2 to 2 ' SO 
 
 is6 
 
 9 to o : <;o . 
 
 IQ2 
 
 3 to ^ * so 
 
 227 
 
 10 to 10:59. ... 
 
 y 2 
 24.6 
 
 4 to 4." SO 
 
 260 
 
 1 1 to 1 1 : 59 
 
 2S7 
 
 s to s so 
 
 I4.S 
 
 12 to 12:59. ... 
 
 4.Q 
 
 o * o ov 
 Other hours 
 
 280 
 
 
 
 
 
 The figures given in Table V represent factories in which 
 the working hours are not similar. While in general the working 
 day is from 7 A.M. to 6 P.M. with a rest period from 12 M. to i 
 P.M. in the factories to which the statistics in Table V apply, 
 there are important variations. In many factories especially 
 where women are employed, the day begins at 7:30 A.M. The 
 time of the lunch period at noon varies in one plant employing 
 
EMORY S. BOGARDUS 43 
 
 about 3,000 men and women, the writer found that practically 
 one-half of this number take their lunch period from n 130 to 
 12. Frequently the employees begin their afternoon period of 
 work at 12 145 P.M., and in some cities at 12 130 P.M. In the large 
 cities the working day closes in a considerable number of cases 
 at 5 130 P.M. or 5 P.M. ; and if there is Saturday afternoon work, 
 at 4 P.M. A study of the work-hours of the factories to which 
 the figures in Table V apply shows that from 7 A.M. to 8 A.M., 
 from ii A.M. to i P.M., and after 5 P.M. a lesser number of em- 
 ployees are at work than during the other work-hours, when the 
 employees of all the factories represented are considered in the 
 aggregate. If the table shows a smaller number of accidents 
 during the hour from 7 to 8 A.M. than in the succeeding hour, it 
 is not safe to infer that the danger of accident is correspondingly 
 less, since a smaller number of persons are at work from 7 to 8 
 A.M. than during the following hour. In Table V the periods 
 from 8 to 1 1 A.M. and from i to 5 P.M. are of almost uniform 
 employment. 
 
 In considering this period of uniform employment the rate \ 
 of work must be taken into account before definite conclusions 
 may be drawn regarding the influence of fatigue. As pointed , 
 out in Section IV, the greater the speed of work, the greater is 
 the danger of accident, and vice versa. Hence the question \ 
 arises : Is the rate of work uniform in connection with dangerous 
 machinery ? 
 
 In a recent investigation by the United States Bureau of 
 Labor, records were taken from hour to hour from stamping 
 presses equipped with automatic counters for registering the 
 production. Records were kept for twenty- three machines for 
 periods varying from one day to seven. With reference to the 
 results, the report of the Bureau of Labor says that it is ex- 
 tremely probable "that there is an average slackening of activity 
 on the part of the workers in the last hour and a half of the 
 day." 1 If this explanation be correct and be applied to the after- 
 
 * Quoted from proof-sheets of Vol. XI of the "Report on Condition of Woman and Child 
 Wage-Earners in the United States," Senate Doc. No. 645, 6ist Cong., 2d sess. 
 
44 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 noon period of uniform employment from i to 5 P.M., it will be 
 seen that the last hour from 4 to 5 P.M. is probably one during 
 which the rate of activity is much less than during the preceding 
 hours. In general and on the average it may be assumed that 
 the afternoon period from i to 4 P.M., like the forenoon period 
 from 8 to ii A.M., is one of both uniform employment and of 
 fairly uniform rapidity of work. 
 
 From each of the three-hour periods of both uniform em- 
 ployment and rapidity of work three other factors have been 
 eliminated: (a) During the last half -hour of work before noon 
 and before the time for closing there is likely to occur what is 
 called the "final spurt," which comes with the realization that 
 one's work is nearly finished and which tends to reduce the dan- 
 ger of accident because of the increased volitional forces brought 
 to bear upon the work, (b) The close of the working period is 
 to some extent a period of readjustment accumulated work is 
 removed; new stock is secured in order that the next period of 
 activity may go forward unhindered. 2 (c) There enters also the 
 sense of accomplishment. The worker may proceed more lei- 
 surely to the close of the period, after he has accomplished a cer- 
 tain amount of work and has his task well in hand. 3 
 
 The question arises : How do the afternoon totals compare 
 with the forenoon totals ? But an adequate basis of comparison 
 is not present. In the first place, the forenoon period is often 
 longer than the afternoon period. Further, it is not correct to 
 compare the totals for the hours from i to 4 P.M. with those from 
 8 to ii A.M. because the existence of a Saturday half-holiday 
 during the summer, and in some trades throughout the year, de- 
 presses the afternoon totals, while a high number of accidents 
 on Monday mornings after the Sunday holiday unduly increases 
 the forenoon totals. Also/ the evidence indicates that the rapidity 
 of work is considerably lessened in the last hour and a half of 
 the day's work and the chances of accident are correspondingly 
 decreased. 
 
 * Op. cit., Senate Doc. No. 645, Vol. I, 395- 
 'Ibid. 
 
EMORY S. BOGARDUS 
 
 45 
 
 (^ Fig. 3 illustrates Table V and makes graphic the more or 
 less regular increase in the number of accidents during both the 
 forenoon and afternoon periods of uniform employment and of 
 uniform speed of activity.) The fall in the number of accidents 
 following the noon period of rest is striking. When it is re- 
 called that Table V and Fig. 3 apply only to those accidents 
 (Class B) which were immediately preceded by muscular inac- 
 curacies of small proportion (see Section III), further illu- 
 mination thus will be given to the law of fatigue as stated at the 
 
 No. of a 
 Accidents 
 7 to 8 A.M. 
 
 8 tO Q A.M. 
 9 to IO A.M. 
 10 tO IX A.M. 
 XI A.M. tO 12 M. 
 
 12 M. tO I P.M. 
 X tO 2 P.M. 
 2 tO 3 P.M. 
 3 to 4 P.M. 
 4 to 5 P.M. 
 5 to 6 P.M. 
 Other hours 
 
 ccidents 50 xoo 150 200 250 300 
 
 
 
 
 
 
 
 
 
 | 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 I 
 
 
 
 
 
 
 
 
 1 
 
 
 | 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 |_ 
 
 
 
 
 
 
 
 
 J 
 
 
 
 
 I 
 
 
 
 
 
 
 
 
 
 
 " 
 
 
 FIG. 3 
 
 close of Section III; namely, that (the increasing muscular inac- 
 curacy accompanying uninterrupted work results in increasing 
 numbers of accidents.) 
 
 The question of accident-hours has hardly been raised as yet 
 in the United States. Only a few states, such as Wisconsin, 
 Minnesota, and Illinois, require that the exact time of accidents 
 be reported to the offices of factory inspection. At best, sta- 
 tistics of accident-hours in the United States are unsatisfactory. 
 Table VI is prepared frorn the accident records of Wisconsin 
 for the year 1 907-8.* It should be noted that in Table VI 
 and in the tables of accident-hours which follow that all accidents 
 are included those due to the breaking of machinery, etc.; 
 whereas in Table V (Illinois statistics) only those accidents are 
 
 4 Bur. of Labor and Industr. Statis. (Wis.), itfh Biennial Report, Part I (1007-8), 78. 
 
4 6 
 
 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 classified which conceivably might have been avoided if the in- 
 jured parties had had accurate muscular control. The question 
 is raised by the compiler of the Wisconsin figures why the largest 
 number of accidents did not occur in the last hour of work. 
 Since many establishments close at some point between 5 and 6 
 P.M. the lessened number of accidents for this hour may be ac- 
 counted for in this way in large measure. The explanation for 
 the relative decrease in the number of accidents from n to 12 
 P.M. may be threefold: (a) As in Illinois, there may be whole 
 shifts of men and women who take their lunch period at 1 1 130 
 A.M., and hence are not working during the last half -hour; (b) 
 There presumably is a slackening of the rate of work with a 
 correlative decrease in danger of accident; (c) Some workmen 
 with a surplus of energy may experience the "final spurt" and 
 thus the danger of accident may be lessened. 
 
 TABLE VI 
 
 ACCIDENT-HOURS (WISCONSIN, 1907-8) 
 
 Morning 
 
 Accidents 
 
 Afternoon 
 
 Accidents 
 
 7 to 7 * "sO 
 
 156 
 
 i to i : <\o . . 
 
 247 
 
 8 to 8 59 
 
 2/14 
 
 2 to 2 : so . . 
 
 4O7 
 
 9 to o ' ^o 
 
 4.27 
 
 2 to 3 : so . . 
 
 4-zc 
 
 10 to 10* 59 
 
 486 
 
 4 to 4: <o . . 
 
 446 
 
 1 1 to 1 1 ' 59 . . 
 
 376 
 
 5 to s : so . . 
 
 277 
 
 
 
 
 
 At all events, a consideration of the Wisconsin statistics for 
 the hours of uniform employment and uniform rapidity from 8 
 to ii A.M. and from i to 4 P.M. would eliminate many extrane- 
 ous elements and justify the conclusion, as in the case of the 
 Illinois statistics, that fatigue is a causal factor in accidents. 
 
 Table VII shows the distribution of accidents through the 
 day in New England and southern cotton mills. 5 The table in- 
 cludes figures from three series. 
 
 Of the three series presented, that of accidents in one New England 
 mill for an eight-year period is the most significant, since it shows the 
 comparatively unhindered operation of uniform causes. In this series the 
 percentage of accidents gradually rises during the forenoon until n o'clock, 
 
 * Op. cit., Senate Doc. No. 645, Vol. I, 395. 
 
EMORY S. BOGARDUS 
 
 47 
 
 and then there is a decided drop. In the afternoon the percentage remains 
 comparatively low until 4 o'clock, when there is a considerable rise followed 
 
 by a large decrease in the percentage during the last hour of the day 
 
 The accident distribution is apparently a product of at least two factors. 
 The worker in beginning gradually increases his speed, the result being a 
 combination of increasing speed with growing fatigue. A basis is thus 
 furnished for a growing accident rate. As already indicated, there is an 
 increase in percentage of accidents both in morning and afternoon; but in 
 the latter period the process is not repeated on the same scale as during the 
 morning hours. The drop at the end of the period has several factors whirh 
 vary from industry to industry. The fatigue is itself a large element in the 
 result. It finally overcomes to a degree the driving energy which has kept 
 up the speed. 8 
 
 TABLE VII 
 
 ACCIDENT-HOURS (iN COTTON MlLLS) 
 
 Morning 
 
 Accidents 
 
 Afternoon 
 
 Accidents 
 
 7:01 to 8 
 
 163 
 
 i :oi to 2 
 
 14.1 
 
 8 * 01 to o 
 
 208 
 
 2 " OI to 3 
 
 i6 
 
 O'OI to IO 
 
 2CJI 
 
 3'OI to d 
 
 IQ'l 
 
 lO'OI to II 
 
 242 
 
 4*01 to ^ 
 
 14.7 
 
 II *OI tO 12 
 
 121 
 
 5 'oi to 6 
 
 O2 
 
 
 
 
 
 In presenting tables of accident-hours compiled from the 
 records of nineteen establishments engaged in metal manufacture 
 (a special inquiry made by the United States Department of 
 Labor) and from the unpublished records of the Indiana depart- 
 ment of factory inspection for two years, the Bureau of Labor 
 says, by way of analysis of the figures : 
 
 It is evident that in the inter-relation of influences acting upon the situa- 
 tion now one and now another may be dominant. The most constant factor 
 will be fatigue. It will be present in varying proportion in every case. It 
 may act with the tendency to increase speed and thus to produce a greater 
 number of accidents. It may in the end become so pronounced that speed 
 is reduced and the accident rate lowered. (It should not be forgotten, how- 
 ever, that this lowered accident rate is presumably far higher than it would 
 be were the laborer working at this reduced rate while yet unfatigued.) 
 
 There will be some tendency to minimize the factor of fatigue in the 
 above process, because it is not a matter of acute sensation. It gradually 
 upsets those nice adjustments of the living organism upon which depend 
 efficient labor and the safety of the worker Reduce the alertness and 
 
 6 Ibid. 
 

 48 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 the exactness with which the body responds to the necessities of its labor, 
 and by just so much have you increased the liability that the hand will be 
 misplaced that fraction of an inch which means mutilation. 
 
 The law of fatigue is a universal law. We may change its operation, but 
 
 cannot eliminate the fact The weaker organism suffers soonest and 
 
 most. 1 
 
 It may be well to note here the two methods of tabulating 
 accidents according to hours. The unsatisfactoriness of both 
 methods is due to the fact that accidents occurring from one to 
 fifteen minutes before or after a given hour, say 8 A.M., are 
 frequently reported as occurring at 8 A.M. In Table VII, 
 accidents are tabulated from 7:01 to 8 A.M., etc., and accidents 
 which really happen after eight o'clock and belong to the second 
 hour are included in the record for the first hour of work. Thus 
 to each hour-period of the day many accidents are accredited 
 which really belong to the succeeding hour. Ten to eleven A.M. 
 in Table VII, for instance, really means 10:15 to n 115 A.M. or 
 thereabouts, and the greatest number of accidents really occurred 
 somewhat later in both the forenoon and afternoon periods than 
 is indicated. 
 
 On the other hand, in Tables V and VI accidents have been 
 tabulated from 7 to 7.59 A.M., etc. This method is incorrect in 
 the other direction. Some accidents occurring shortly before 
 8 A.M. and in the first hour of work have been reported as oc- 
 curring at 8 A.M., and hence are included in the record for the 
 second-hour period. In the succeeding ten tables both methods 
 have been used, as far as the writer can determine. On the 
 whole, it appears that the inaccuracies of the two sets of errors 
 to a certain extent counterbalance each other. 
 
 The Minnesota Bureau of Labor has recently published a table 
 giving a classification of hours of the accidents which were re- 
 ported to the Bureau during the year August i, 1909, to July 
 31, 1910. In commenting on this table the Bureau says: 8 
 
 Fatigue and nerve strain also have a place among the causes of acci- 
 dents and the table and chart below (see Report) suggest that it may be an 
 important place. The question should be given further consideration. 
 
 7 0p. cit., Senate Doc. No. 645, Vol. I, 395- 
 
 1 Bureau of Labor, etc. (Minn.), izth Biennial Report (1900-10), 137, 140. 
 
EMORY S. BOGARDUS 
 
 49 
 
 The curves seem conclusive that .... fatigue largely explains the lapse 
 of attention that causes injury in the later portion of the working period 
 
 In the study of accident-hours, European countries, notably 
 France and Germany, are far ahead of the United States. In 
 France, a study of accident-hours has been made by Professor A. 
 Imbert of the University of Montpelier. He found that a study 
 of 5,534 accidents distributed among 140,407 workers in the 
 cir conscription de Toulouse gave results similar to those indi- 
 cated by Table VIII. These statistics apply to wood-workers, 
 the chemical industries, building trades, etc. Table VIII refers 
 
 TABLE VIII 
 
 ACCIDENT-HOURS (FRANCE, 1904) 
 
 Morning 
 
 Accidents 
 
 Afternoon 
 
 Accidents 
 
 7 to 8. . 
 
 232 
 
 I to 2 
 
 132 
 
 8 to o 
 
 7QI? 
 
 2 tO 3 
 
 ?io 
 
 o to 10 
 
 24.0 
 
 7 to 4.. 
 
 421 
 
 10 to ii 
 
 O^ 
 4?8 
 
 4 to "?. 
 
 CI2, 
 
 II to 12 
 
 202 
 
 s to 6. . . 
 
 2 ( \4 
 
 
 
 
 
 to the year 1904, represents all industries, and covers the depart- 
 ments of Herault, Aveyron, Lozere, Cantal, and Tarn. 9 Imbert 
 interprets these figures as follows : 
 
 A large number of accidents result directly from the physical or mental 
 fatigue of the workmen at the moment of the accident and this assertion 
 
 can easily be proved by innumerable instances One result .... is 
 
 that fatigue renders the workman less apt to avoid accident since he cannot 
 make ("ne peut plus realiser") as intense an effort as usual nor execute 
 
 movements of his normal rapidity Two facts are shown very clearly 
 
 by this table of figures (see Table VIII) ; namely, the considerable share 
 played by fatigue in producing accidents and the equally important influence, 
 in the inverse sense, of the midday hour of rest. 10 
 
 Fatigue being the inevitable consequence of work, accidents inexorably 
 increase from hour to hour. 
 
 Imbert refers to the inquiries made by M. Le Roy, division 
 factory inspector of Toulouse, for the years 1903 and 1904, and 
 says that the results, which apply to several thousands of acci- 
 
 A. Imbert and M. Mestre, "Nouvelles statistiques d'accidents du travail," Rev. Scien- 
 tifique, October 21, 1905, 521. 
 
 10 A. Imbert, "Les accidents du travail et les compagnies d'assurances," Rev. Scientifique, 
 June 4, 1904, 715. 
 
 " See Footnote 7. 
 
RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 dents, are in harmony with his results ("toutes, sans exception, 
 presentent les caracteres generaux que nous avons enumere 
 cidessus"). An excerpt from M. Le Roy's analysis is subjoined. 
 It is indisputable, in fact, that the more fatigued a worker is, the more 
 liable he is to accident. The accident is then the consequence of the com- 
 bined results of physical depression, relaxed attention, and less rapid move- 
 ments All these data and the various statistics to which reference 
 
 has been made bring us necessarily to a consideration of fatigue as one of 
 
 the chief causes of accidents This cerebral fatigue, due to monotonous. 
 
 speeded-up labor, induces a nervous depression which is betray^ Ky inaf- 
 tentiorvvery often resulting in accident It is precisely this form of fatigue 
 that explains the increasing progression of accidents with the progress of 
 working hours in industries where work is most often limited to watching 
 machinery. 13 
 
 Germany was among the first nations to require that accident- 
 hours be reported. Table IX is compiled from the German acci- 
 dent statistics for the years 1887 and 1891, and applies to all of 
 the various trades and to agriculture combined. The accidents 
 represented in Table IX appear to have been reported with more 
 system than that shown in the reporting of accident-hours in 
 other countries, with the possible exception of France. Table 
 IX represents a wide and comprehensive range of accidents. 13 
 
 TABLE IX 
 
 ACCIDENT-HOURS (GERMANY, 1887, 1891) 
 
 Morning 
 
 Accidents 
 
 Afternoon 
 
 Accidents 
 
 7 to 8 
 
 IX4I 
 
 I to 2 
 
 1,727 
 
 8 to 9 
 
 1. 06 1 
 
 2 to 3 . . 
 
 2,44. c 
 
 9 to 10 
 
 2,4-QO 
 
 3 to 4.. . 
 
 3,220 
 
 10 to ii 
 
 2 Ate 
 
 4 to ^ , . 
 
 3,104 
 
 II to 12 
 
 3,213 
 
 S to 6. . 
 
 2,824 
 
 
 
 
 
 The results of the investigations made in Germany in the 
 years 1897 and 1907 are similar in the main to those given in 
 Table IX. 14 Of the 81,284 accident cases reported for the year 
 
 11 See Brandeis and Goldmark, Ten-Hour Law for Women (New York), 241, 242. 
 
 13 See E. R. Krejcsi, Cong. Intern. d'Hyg. et de Demog., VII,328; also the 24th Annual 
 Report, Commissioner of Labor (U.S.), Vol. I, 1132-34; also the i?th Annual Report, New 
 York Bureau of Labor Statistics, 73-939- 
 
 14 See Amtliche Nachrichten des Reichs-Versicherungsamts, Beiheft I, Teil i (1910); also 
 see Bulletin of the Bureau of Labor, No. 92 (January, 1911). It should be noted that these 
 German statistics refer to fatal accidents and to those cases where the injured was disabled 
 for more than thirteen weeks. They include the accident reports from the mining, quarrying, 
 iron-and-steel, metal-working, textile, wood-working industries and from the building trades. 
 
EMORY S. BOGARDUS 
 
 1907, 13.87 per cent occurred between the hours of 6 and 9 A.M., 
 and 28.42 per cent between the hours of 9 A.M. and 12 M. ; while 
 13.81 per cent happened between the hours of 12 and 3 P.M., and 
 26.32 per cent between the hours of 3 and 6 P.M. In regard to 
 the 45,971 accident cases reported for the year 1897, the per- 
 centages of the accidents for the different sections of the day 
 run approximately parallel with those given for the year 1907. 
 For both years the increase in the number of accidents during 
 the forenoon and afternoon periods is most pronounced in the 
 metal-working trades. The percentages for the 424 accident 
 cases reported in 1907 for the South German metal-workers were 
 as follows : 12.89 P 61 " cent f r the hours from 6 to 9 A.M., and 
 37.23 per cent for the hours from 9 A.M. to 12 M., and 11.93 P er 
 cent for the hours from 12 M. to 3 P.M., and 32.22 per cent for 
 the hours from 3 to 6 P.M. 
 
 In England little attention has been given to accident-hours; 
 a partial and inadequate list of accidents in factories and work- 
 shops for the year 1903 may be found in the British Sessional 
 Papers, House of Lords. 15 Table X gives the figures of a recent 
 study of accident-hours in Belgium (1907) and applies to all 
 industries. 18 
 
 TABLE X 
 
 ACCIDENT-HOURS (BELGIUM, 1907). 
 
 Morning 
 
 Accidents 
 
 Afternoon 
 
 Accidents 
 
 7 to 8 
 
 roo 
 
 I to 2 
 
 1*6 
 
 8 to o 
 
 AC A 
 
 a to < . . 
 
 4O^ 
 
 9 to 10 
 
 ;86 
 
 3 to 4.. . 
 
 787 
 
 10 to ii 
 
 83 < 
 
 4. to < . . 
 
 <O4 
 
 II to 12 
 
 675 
 
 <; to 6 . . 
 
 568 
 
 
 
 
 
 In Copenhagen, Dr. H. Bille-Top kept a record for ten years 
 (1898 to 1907) of the industrial-accident cases which he was 
 called upon to attend according to the hour of their occur- 
 ence. 17 Dr. Bille-Top attributes the increase in the number of 
 
 "Vol. LIX, an. 
 
 " Ministere de 1'industrie et du travail, Rapports annuels de ^inspection du travail (1907), 
 ai2, 213. 
 
 " H. Bille-Top, "Die Verteilung der Unglucksfalle der Arbeiten, die Wochentage und die 
 Tagesstunden," Centralbl. /. Allegemein. Gesundheitspfl., XXVII, 197. 
 
52 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 accidents in both the forenoon and afternoon periods to increas- 
 ing fatigue ("zunehmender Miidigkeit, zunehmender Abge- 
 spanntheit" ) . 
 
 Professor G. Pieraccini and Dr. R. Maffei, head physicians 
 in the Royal Main Hospital, Florence, have made an investiga- 
 tion of the accidents (with reference to accident-hours) which 
 took place in some of the railway machine-shops of Italy (1901 
 to 1905). The results of their tabulation of accident-hours are 
 given in Table XI. They omit the first hour of work of both 
 
 TABLE XI 
 
 ACCIDENT-HOURS (ITALY) 
 
 Hours of Work 
 
 Accidents 
 
 2d 
 
 206* 
 
 *d. . 
 
 258 
 
 4th. . 
 
 3 
 
 3.2 A^ 
 
 5th.. 
 
 32^ 
 
 
 
 periods of the day because fewer workmen are at work than 
 during the succeeding hours. The accidents for the correspond- 
 ing hours of the forenoon and afternoon periods are added to- 
 gether. Professor Pieraccini concludes that the protraction of 
 the hours of labor raises the number of accidents with each suc- 
 cessive hour, in both the first and second half of the day. 18 
 
 In Vienna, Dr. Leo Verkauf has made some investigation of 
 accident-time in connection with insurance studies. His figures 
 refer to those industries (in Austria) in which a short recess, 
 sometimes of thirty minutes, is given at 10 A.M. and at 4 P.M. 19 
 They show an increase in the number of accidents for the first 
 three hours of the forenoon and of the afternoon periods. With- 
 out some sort of comparative basis covering the same industries, 
 the effects of the recess are difficult to determine. 
 
 Many conditions in Europe are different from those in the 
 United States. Yet the fact that European investigations are 
 uniformly emphatic in the assertion that the danger of accident 
 increases with continued work is most significant for the Ameri- 
 can situation. The fatigue effects of the great and feverish haste 
 
 11 See Brandeis and Goldmark, op. tit., 252. 
 ' E. R. Krejcsi, op. tit., 328. 
 
EMORY S. BOGARDUS 
 
 53 
 
 at which things are done in the United States must be added to 
 the regular fatigue effects of the more deliberate European 
 methods of operation. 
 
 Table XII gives the statistics to which reference has been 
 made in the preceding paragraphs. The totals appear at the 
 bottom of the table. From these figures it is not possible to 
 make a comparison of the number of accidents occurring in the 
 forenoon with those of the afternoon because the Saturday and 
 other half-holidays depress the afternoon totals and because the 
 forenoon period is frequently of greater length than the after- 
 noon period. No attempt has been made to tabulate accidents 
 
 TABLE XII 
 SUMMARY OF ACCIDENT-HOURS 
 
 Hours 
 
 7 to 8 
 
 8 to 9 
 
 9 to 10 
 
 lotoii 
 
 II tOI2 
 
 la to i 
 
 x to a 
 
 a to 3 
 
 3 to 4 
 
 4 to 5 
 
 5 to 6 
 
 Illinois 
 
 97 
 156 
 
 163 
 380 
 818 
 
 25 
 232 
 
 794 
 
 747 
 500 
 
 9 
 ii 
 
 ISO 
 244 
 
 208 
 
 538 
 1,072 
 30 
 305 
 
 815 
 
 1,146 
 454 
 19 
 
 12 
 
 193 
 427 
 
 251 
 653 
 1,332 
 2O 
 340 
 
 1,069 
 
 1,421 
 586 
 
 18 
 16 
 
 246 
 
 486 
 
 242 
 
 573 
 1,137 
 57 
 478 
 
 i,598 
 
 i,857 
 835 
 27 
 20 
 
 257 
 376 
 
 121 
 226 
 765 
 63 
 292 
 
 1,59 
 
 1,623 
 675 
 46 
 
 34 
 
 49 
 94 
 
 67 
 233 
 368 
 
 50 
 587 
 
 738 
 74 
 23 
 5 
 
 ill 
 247 
 
 141 
 439 
 943 
 18 
 132 
 
 745 
 
 982 
 136 
 ii 
 
 9 
 
 156 
 407 
 
 165 
 634 
 1,054 
 40 
 310 
 
 1,037 
 
 1,408 
 403 
 
 18 
 14 
 
 227 
 
 435 
 
 203 
 590 
 1,199 
 
 45 
 42i 
 
 1,243 
 
 1,986 
 
 787 
 
 22 
 26 
 
 260 
 446 
 
 147 
 412 
 
 899 
 105 
 513 
 
 1,178 
 
 2,016 
 
 504 
 24 
 
 29 
 
 145 
 
 277 
 
 92 
 159 
 353 
 118 
 
 254 
 1,306 
 
 i,5i8 
 568 
 
 24 
 20 
 
 Wisconsin .... 
 U.S. (cotton 
 mills) 
 
 Minnesota 
 Indiana, etc. . . 
 France(foriQ03) 
 France (for 1 904) 
 Germany (for 
 1887) 
 
 Germany (for 
 1801) 
 
 Belgium 
 
 England 
 
 Denmark 
 Total 
 
 3,732 
 
 4,993 
 
 6,326 
 
 7,566 
 
 7,o68 
 
 2,289 
 
 3,914 
 
 5,646 
 
 7,184 
 
 6,533 
 
 4,834 
 
 
 according to the days of the week. Not only are there insuf- 
 ficient statistics to be tabulated in this way, but the Sunday 
 period of supposed rest introduces new and complex factors. 
 The records for the day following pay-nights indicate that ab- 
 normal factors have entered. As far as accident records go 
 which may be tabulated by the days of the week, they indicate 
 a large number of accidents on Monday, a much less number on 
 Tuesday, a gradual rise till the close of the week, when the 
 number of accidents on Monday is exceeded. "In many indus- 
 tries, notably the iron and steel, mining, textile, and railway, the 
 
54 
 
 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 number of accidents steadily increases from the first or middle 
 of the week and attains a maximum for Saturdays." 20 
 
 recreation seems to unfit workmen for steady work on Monday, 
 "but fatigue evidently plays a role also; for even on Monday 
 the number of accidents between 9 A.M and 12 M. is larger than 
 between 6 and 9 A.M., even in proportion to the hours worked 
 in the two periods." 
 
 Table XII gives the same general results as Table V (Illinois 
 statistics) : (a) A marked increase of accidents during the fore- 
 noon period; (&) A decided fall after the noon period; and (c) 
 Another marked rise in the afternoon period. Accurate conclu- 
 sions regarding fatigue effects must be confined to those work- 
 hours when the number actually at work is uniform and when 
 the rapidity of work is fairly uniform. The hours of uniform 
 employment and of uniform rapidity of work as determined in 
 the early portion of this section, are from 8 to 11 A.M. and from 
 i to 4 P.M. On the basis of this analysis, Table XIII has been 
 constructed; the figures have been taken from Table XII. The 
 number of accidents for the first hour of the three-hour morning 
 
 TABLE XIII 
 ACCIDENT-HOURS (FINAL RESULTS) 
 
 
 FIRST HOUR 
 
 SECOND HOUR 
 
 THIRD HOUR 
 
 
 8 to 9 Morning 
 x to 2 Afternoon 
 
 9 to 10 Morning 
 2 to 3 Afternoon 
 
 10 to ii Morning 
 3 to 4 Afternoon 
 
 Illinois 
 
 261 
 
 340 
 
 473 
 
 ^Visconsin . . 
 
 4QI 
 
 834 
 
 O2I 
 
 U S Cotton Mills. 
 
 74.0 
 
 416 
 
 44 c 
 
 Tvlinnesota. 
 
 O77 
 
 1,287 
 
 I,l6^ 
 
 Indiana 
 
 2,OI< 
 
 2,386 
 
 2,336 
 
 France (1003) 
 
 48 
 
 60 
 
 IO2 
 
 France (1004) 
 
 A27 
 
 6<o 
 
 600 
 
 Germany (1887) 
 
 t.c6o 
 
 2,106 
 
 2,841 
 
 Germany (1891) 
 
 2,128 
 
 2,820 
 
 3,843 
 
 Belgium 
 
 (TQO 
 
 080 
 
 1,622 
 
 England 
 
 JQ 
 
 36 
 
 49 
 
 Denmark 
 
 21 
 
 3O 
 
 46 
 
 Italy 
 
 206 
 
 258 
 
 324 
 
 
 
 
 
 Total 
 
 9,117 
 
 12,230 
 
 15,064 
 
 
 
 
 
 ' Bureau of Labor Statistics (New York), XVII, 786. 
 
EMORY S. BOGARDUS 55 
 
 period of uniform employment and rapidity has been added to 
 the number of accidents for the first hour of the afternoon period 
 of uniform employment and rapidity, and so on. The more or 
 less regular increase in the number of accidents, hour by hour, 
 from 9,113 to 12,230 and from 12,230 to 15,064, indicates quite 
 definitely the results of fatigue in terms of actual accidents 
 inasmuch as extraneous elements have been largely accounted 
 for and not included in these figures. 
 
 Table XIII serves as a basis for the following conclusion: 
 Continuous work, other things being equal, is accompanied, hour 
 by hour, by an increasing number of accidents. Table XIII adds 
 weight to the statement of the law of fatigue given at the close 
 of Section III ; the increasing muscular inaccuracy which accom- 
 panies uninterrupted work results in increasing danger of acci- 
 dent. Table XIII is offered in support of the thesis of this 
 investigation, that fatigue is a cause of industrial accidents. 
 
 In the following section an attempt will be made to answer 
 the question, Has fatigue attracted attention to itself to the 
 extent that it has been indicted as a cause of accidents by men 
 of judicial and conservative mind? 
 
 VI. JUDICIAL FINDINGS AND DECISIONS 
 
 The accident statistics presented in the preceding section were 
 related mainly to the development of fatigue and to the increase 
 of accidents during the regular ten-hour day. The figures for 
 accidents occurring during overtime work are very inade- 
 quate. Light is thrown on this point from two important 
 sources : (a) the reports of the Interstate Commerce Commission, 
 and (&) the decisions of the courts. Although the material used 
 in this chapter and gleaned from these two sources is largely 
 incidental to the main function of these sources, it is for that 
 reason of special value for this investigation. The overtime 
 accident cases cited in this section are not intended to show the 
 relative danger of working "overtime," since there is no ade- 
 quate basis of comparison. The accident cases cited here are 
 those apparently due to fatigue of overwork and per se are 
 offered as additional evidence in defense of the thesis that fatigue 
 
56 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 is a cause of accidents. No attempt has been made here to offer 
 an exhaustive list of such cases. The purpose at this point is 
 to cite cases which will establish the fact, not the quantitative 
 extent, of fatigue resulting from working overtime as a cause 
 of accidents. 
 
 For several years past the Interstate Commerce Commission 
 has concerned itself with a study of railway accidents; its find- 
 ings are published quarterly. An excerpt germane to this inves- 
 tigation follows: 
 
 In nearly or quite every bulletin that has been issued, it has been neces- 
 sary to record one or more collisions due to the mistakes or negligence of 
 men who have been on duty so many hours as to raise the supposition, if not 
 the presumption, that they had become drowsy, if they had not actually 
 fallen asleep; and cases in which enginemen are definitely reported as being 
 asleep on duty are common. 1 
 
 Table XIV presents a list of fifty- four railway accidents com- 
 piled from the reports of the Interstate Commerce Commission. 
 In these cases, the person or persons responsible for the accident 
 had been on duty periods of time varying from eleven hours and 
 nineteen minutes to thirty-nine hours and twenty-five minutes 
 without intermission (except where noted). 2 In respect to the 
 accidents tabulated, the Interstate Commerce Commission either 
 states or directly implies that "the men at fault had been on duty 
 an excessive number of hours/' 3 The implication is clear that the 
 fatigue of overtime work was the chief cause of these accidents 
 involving loss of life and property. The facts upon which Table 
 XIV is based are submitted as proof from an angle different 
 from that of the preceding chapters that fatigue is a cause of acci- 
 dents. Typical illustrations of what happened directly previous 
 to the occurrence of the given accidents are given : 
 
 Accident No. 8 (Table XIV). Flagman, who had been ordered to hold 
 one of the trains, went into caboose to get red light; sat down to warm him- 
 self and dry his clothes; fell asleep; had been on duty sixteen and a half 
 hours. 
 
 1 Interstate Commerce Commission, Report, No. 18, 10. 
 
 ' The size of Table XTV is such that limitations of space do not permit its publication. 
 Its contents, however, are indicated here. 
 3 See Footnote i. 
 
EMORY S. BOGARDUS 57 
 
 Accident No. 30. Due to forgetfulness on the part of an engineman 21 
 years old who had been on duty thirty-nine hours and twenty-five minutes. 
 
 Accident No. 34. Operator fell asleep and failed to deliver meeting 
 order; on duty twenty-four hours. 
 
 Accident No. 38. Engineman fell asleep and slept two minutes; had 
 been on duty twenty-one hours. 
 
 Accident No. 32. (Forty-two killed and injured.) Operator turned 
 
 east-bound passenger train on wrong delivery track He had been on 
 
 duty twenty hours and fifty minutes. 
 
 Accident No. 40. Engineman fell asleep and passed automatic block 
 signal set against him; also passed flagman; had been on duty seventeen 
 hours. 
 
 Accident No. 41. Engineman (killed) disregarded flag; had been on 
 duty twenty-eight hours. 
 
 Accident No. 46. (Fifty-six killed and injured.) Misplaced switch at 
 meeting point. Brakeman had been on duty twenty hours and forty minutes. 
 
 Accident No. 53. (Eight killed and injured.) The conductor and flag- 
 man of the freight had been on duty sixteen hours and fifty minutes. The 
 freight was delayed .... the flagman was left at "D" to stop the north- 
 bound train After remaining at this station about seven hours (the 
 
 flagman) was sitting on the steps of a caboose of a freight train standing on 
 the side track, with the lantern on one of the lower steps of the caboose 
 between his feet. While so sitting he fell asleep and was not roused until the 
 north-bound train came along and passed him (and ran into the delayed 
 freight). 
 
 Table XIV includes fifty- four collisions and derailments in 
 which the total number of killed and injured was five hundred 
 and forty-one persons; the total damage to engines, cars, 
 and roadbed was $512,453. When the Interstate Commerce 
 Commission gives as the chief cause in each of these instances the 
 fact that the men at fault had been on duty an excessive number 
 of hours, and when the circumstances preceding the given acci- 
 dents are considered, the proof is strong that the fatigue of over- 
 work was beyond doubt the causal factor. Table XIV presents 
 fifty-four concrete, important cases in support of the proposition 
 that fatigue is a cause of accidents. 
 
 Further testimony in defense of the thesis of this treatise has 
 been obtained from decisions of the courts this is presented in 
 the paragraphs which follow. Seven cases will be cited here in 
 which the courts have decided that fatigue was a cause of the 
 given accidents. 
 
58 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 (a) In the case of Pennsylvania v. McCaffrey, the Supreme 
 Court of the State of Indiana held : 
 
 Unless it be that a master has a right to require a servant to stand at 
 his post of duty without food or rest for nineteen hours every day, Sundays 
 included, and that such conduct is not a breach of duty to the public as well 
 as to its other servants, it follows that the appellant (the railway company) 
 in this case has not performed its duty towards decedent without which it is 
 liable if this negligence was the proximate cause of his accident. That it 
 was, it is clear. The law of nature is inexorable in its demands. The crav- 
 ings of hunger must be appeased. The laws of humanity declare that every 
 man fit to be a member of a train crew must have three meals, some rest, 
 and eight hours sleep a day. The appellee well says: "Deprived of these 
 requisites of intelligent life, a soldier becomes a coward; a workingman a 
 drone." Any being would lose his strength if worked a few months by the 
 time schedule provided for this crew. Every statute and employers' rule is 
 made in the presence of, and subject to the laws of nature. Hunger, thirst, 
 and sleep are imperative; and when a schedule is made of nineteen con- 
 secutive hours of service on a train, and no provision is made by the company 
 for their supply of food, it is understood that the employees must, of neces- 
 sity, at times during the service, leave their places to get their meals. So 
 that when the engineer and conductor left the train, after thirteen hours' 
 service, on the day of the accident, to get their suppers it was in obedience 
 to this law of nature an over-ruling necessity, and was not, therefore, 
 negligence on their part. They were not deserters, and their conduct cannot 
 be characterized as offending habits. 4 
 
 (&) In the case of Galveston, H. & S.A. Ry. Co. v. Broivn 
 et a/., the Court of Civic Appeals of Texas said : 
 
 In determining the question of Brown's negligence in going to sleep on 
 his engine, the jury could consider a fact in evidence, viz., that he had been 
 working for appellant for the five days and nights preceding this accident, 
 and was overworked to such an extent that sleep was unavoidable. We think 
 that when appellant so overworks one of its employees that he cannot be 
 expected to stay awake, it ought not to be allowed to say that he was negli- 
 gent in going to sleep, in a question affecting the observance of its rules. 8 
 
 (c) The Supreme Court of the State of Indiana has handed 
 down a decision of special importance in the case of the Republic 
 Iron & Steel Co. v. Ohlet. Excerpts from this decision are given 
 herewith. 
 
 At the time the plaintiff sustained the injury alleged, he had been work- 
 ing continuously, at the instance and request of the defendant, in the said 
 factory, for a period of forty-eight hours, without any sleep; and when he 
 was ordered by said foreman to hold the rod, by reason of his continuous 
 
 4 38 N.E. Reporter, 67. s 59 S.E. Reporter, 930. 
 
EMORY S. BOGARDUS 59 
 
 work, without sleep, he did not realize or appreciate the danger to which he 
 was being subjected It is disclosed that after he had worked continu- 
 ously some thirty-six hours in turning the rod, he informed Kelly, the fore- 
 man, that he did not believe he could endure the labor any longer; but the 
 latter informed him that he must continue at work until the rod was 
 finished. It is not reasonable to assert that a man who has labored continu- 
 ously for a period of forty-eight hours without sleep, or for even a much 
 shorter time, is in his normal condition, or that he under the circumstances 
 can properly exercise all of the faculties or senses with which he is endowed. 
 .... A human being deprived of sleep for the period which appellee was 
 becomes dull in intellect and apprehension, and necessarily must be more or 
 
 less unmindful of his surroundings The jury had the right at least to 
 
 consider this feature of the case, as bearing upon the question whether, under 
 all of the circumstances, appellee apprehended and appreciated the danger 
 to which he was subjected. 9 
 
 (d) In the case of Pelin v. New York Centr. and H.R.R. Co., 
 the Supreme Court of New York, Appellate Division, Fourth 
 Department, reversed the trial court's decision in favor of the 
 defendant and held that there was sufficient evidence to warrant 
 the jury in finding that the injuries were due to exhaustion of 
 certain servants of the corporation, owing to their having been 
 on duty twenty- four consecutive hours (in violation of the 
 statute). The court also held that, although those directing the 
 movements of a train-crew might reasonably have anticipated 
 that the run on which the crew was engaged would not last 
 twenty- four consecutive hours, the conditions of the business of 
 the road having been such that the run could not be completed in 
 less than such time, and an injury having resulted from the ex- 
 haustion of the crew owing to the hours of work, the corporation 
 was liable. Says the court: 
 
 The statute is for protection of employees liable to be injured by the 
 carelessness or oversight of co-employees, caused by exhaustion induced by 
 
 long-continued application to work A railroad company with a crew 
 
 out on a train for more than twenty- four hours may elect to have the trip 
 completed by the same crew. If so it runs the risk of liability for any in- 
 juries sustained by any of its co-employees, and which is the proximate cause 
 
 of exhaustion or inattention caused by such working overtime The 
 
 jury had a right to say that the fact that the flagman was asleep was dug to 
 over- exhaustion by reason of his protracted employment, and that the col- 
 lision might not have occurred had he been in his normal wakeful condition.* 
 
 * 68 N.E. Reporter, 901. *N.Y. Supp., No. 92, 468. 
 
60 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 (e) The case of the Great Northern Railway v. Couture, who 
 was injured while engaged as a brakeman, is directly to the point. 
 "The decision in the reported case is a novel one, and there are 
 but few decisions upon the liability of a master for injuries 
 caused by compelling him to work an excessive number of 
 hours." 8 The court says : 
 
 A master who keeps his servant continuously at work for an undue number 
 of hours is liable in damages for an injury which the servant sustains in the 
 ordinary discharge of his duty, in consequence of his inability, from fatigue 
 and exhaustion, to use the requisite skill and care. [The company was held 
 liable] not upon alleged grounds of having used a defective system of coupling, 
 nor for an excessive rate of speed in bringing the cars together, but for keeping 
 the young man at work for an unreasonable length of time without sleep. 
 .... It could not be otherwise than that his bodily strength was at that time 
 exhausted and that his mental faculties must have been rendered dull and his 
 
 power of observation greatly weakened The learned judge was right 
 
 in holding the present appellants responsible .... in the application of the 
 well-known principle that the employer's care for his workmen must be pro- 
 portional to the risk of the occupation in which he engages them. To exact 
 the extra-hazardous risk of coupling the cars in this instance required a degree 
 of supervision and care on the part of the railway company's officials, which 
 they greatly neglected, in compelling Couture to perform that work at three 
 o'clock in the morning, after a service of forty-eight hours, interrupted only 
 by two breaks, one of six and one of two hours. We have no hesitation in 
 adopting the learned trial-judge's conclusion in this respect, and we believe 
 this considerant of his judgment was sufficiently warranted by the terms of 
 the plaintiff's declaration. 8 
 
 (/) In affirming the decision of a lower court in favor of 
 L. W. Reed, administrator, in the case of Reed v. Southern Rail- 
 way Co., the court states : 
 
 The testimony tended to show that Reed had mistaken the time by reason 
 of the fact that his watch had run down ; but it likewise tended to show that 
 this was caused by the defendant in requiring or permitting Reed to operate 
 his engine for forty-two consecutive hours immediately preceding the col- 
 lision, without rest, and for twenty-seven or twenty-eight hours without 
 anything to eat. This was evidence of negligence [on the part of the South- 
 ern Railway Co.]. 10 
 
 (g) E. D. McCrary, a flagman in the employ of the Southern 
 Railway Company, while lying on the outside of the tracks 
 
 1 7 Amer. and Eng. Annotated Cases, 190. Ibid. I0 55 S.E. Reporter, 218. 
 
EMORY S. BOGARDUS 6 1 
 
 (August 17, 1906) near Sheldon, S.C., presumably asleep, with 
 his shoulders between the cross-ties and his head or a part of it on 
 the rail, was killed by a passing freight. In the trial in the circuit 
 court, the Southern Railway Company was charged with care- 
 less negligence 
 
 in requiring and permitting the said E. D. McCrary to act as flagman upon 
 said train, and to go out as flagman on the trip upon which he was killed, 
 when the said company through its agents in service, knew or could have 
 known that the said E. D. McCrary was in such physical condition, owing to 
 the want of sleep and rest as to render him unfit to perform the duties of 
 flagman, .... and in requiring the said E. D. McCrary to be and remain in 
 the service of the defendant with scarcely any sleep or rest for such a length 
 of time immediately preceding his death as was completely to exhaust his 
 physical and mental powers, as to render him incapable of properly guarding 
 himself, and the train upon which he was flagging, against the dangers inci- 
 dent to the operation of trains. 
 
 The defendants denied the allegation of negligence and wilfulness and 
 interposed the defenses of contributory negligence and assumption of risk." 
 
 The jury rendered a verdict in favor of the plaintiff for 
 $9>5oo, and the defendant appealed. On June 25, 1909, the 
 Supreme Court of South Carolina affirmed the judgment of the 
 circuit court. 
 
 In the seven cases cited, the courts have decided that the re- 
 spective accidents were due (a) not to negligence, but in obe- 
 dience to a law of nature, i.e., in part to the demands of fatigue; 
 (b) to the fact that the injured was overworked to such an extent 
 that sleep, the result of overfatigue, was unavoidable; (c) to the 
 fact that the injured because of fatigue had become dull in appre- 
 hension and unmindful of his surroundings; (d) to overex- 
 haustion by reason of protracted employment; (e) as a conse- 
 quence of the inability of the injured from fatigue and 
 exhaustion to use the requisite skill and care; (/) to the fact that 
 the fatal mistake of the injured was caused by the fatigue of 
 overwork; (g) to the exhaustion of the physical and mental 
 powers of the deceased. 
 
 The fact that fatigue has attracted attention to itself as a 
 cause of accidents to the extent that such a conservative body 
 as the judiciary will thus indict it, is noteworthy. The seven 
 
 " 65 S.E. Reporter, 3. 
 
62 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 cases which have been summarized in the preceding paragraphs 
 are not presented because of any legal points involved or for any 
 reasons other than as a sevenfold argument in support of the 
 thesis that fatigue is a cause of accidents. 
 
 In the following chapter, all the evidence thus far obtained 
 chemical, physiological, neural, psychological, industrial (as 
 such), experimental, statistical, legal will be brought together 
 and offered as a unified whole in defense of the thesis of this 
 investigation. The facts thus collated will be used as a basis 
 for what appears to the writer to be the one best method of re- 
 form and of overcoming fatigue as a cause of industrial acci- 
 dents. 
 
 VII. CONCLUSIONS 
 
 In this study it has been found (Section II) that continued 
 work is accompanied by the using up of energy-giving material 
 of the muscles and nerves and by the production and accumula- 
 tion of toxic fatigue substances. As a result of these processes, 
 muscles respond less and less accurately and the central nervous 
 system becomes less and less efficient in its methods of control. 
 At a certain point in the katabolic processes of the working mus- 
 cle, inhibitory impulses are sent in to the cortical centers over 
 the afferent nerves. These appear in consciousness in the form 
 of sensations of effort, of strain, of fatigue which constitute 
 warnings and which demand a change in the working mechanism. 
 At the same time, the working muscle gradually becomes weaker, 
 owing to the using up of its energy-giving material, and less 
 responsive, owing to the paralyzing effect of the accumulating 
 toxic substances. If the given activity is continued long enough 
 or if continued for a shorter time with a high degree of unre- 
 laxed tension, the cortical centers submit to katabolic processes 
 and become less accurate in controlling peripheral movements. 
 The combined phases of the fatigue process result in muscular 
 inaccuracy extending from the immeasurably small blockings 
 of the finely adjusted musculature on to the failure to make the 
 grossest muscular contractions. 
 
 But the nervous system is so constructed that on occasion it 
 can call out reserve strengths and for short, irregular periods of 
 
EMORY S. BOGARDUS 63 
 
 time ward off disastrous fatigue effects. Thus the progressive 
 loss of muscular control accompanying work is marked by irregu- 
 larly appearing spurts and depressions. Upon these facts the 
 law of fatigue is based which is so generally a fundamental ex- 
 planation of the cause of accidents. Because knowledge of this 
 law appears to be essential to a thorough understanding of in- 
 dustrial accidents, it is restated here: Uninterrupted work is 
 accompanied by muscular inaccuracy which increases irregularly 
 and at a rate dependent on the rate of activity and on the relative 
 difficulty of the given work for the given individual. 
 
 Section III set forth the fact that the increasing muscular 
 inaccuracy which accompanies work is greatly accelerated by the 
 conditions peculiar to industrial conditions by the monotonous 
 and speeded-up operations, by the mental strain which comes 
 from trying to attend to simple operations maintained at a ter- 
 rific rate. When these conditions must be met for excessive 
 hours without adequate rest periods, they lead to failure to make 
 even the grossest co-ordinations to sleep and exhaustion. Since 
 a large proportion, especially of non- fatal injuries, occur in con- 
 nection with dangerous machinery where a muscular inaccuracy 
 of an inch or of a fraction of an inch results in mutilation of 
 the operative, the facts thus far reviewed may be summarized 
 in the statement that uninterrupted work is accompanied by in- 
 creasing muscular inaccuracy, which in turn results in increasing 
 chances of accident. 
 
 In the series of controlled experiments (Section IV), it was 
 definitely shown that even in a short period of work involving 
 monotony, speed, mental strain, where a high degree of voli- 
 tional power might be called out for the full time, practically 
 two-thirds of the muscular inaccuracies occurred in the last half 
 of the period. When the rate of work in these experiments was 
 increased and as long as the rate was a "speeded-up" one for the 
 given individual, the number of errors was and remained ab- 
 normally increased; moreover, the abnormal increase developed 
 quite generally in the second half of the work periods. 
 
 The results of these experiments show that fatigue is an ever- 
 constant factor in continued work, that the appearance of this 
 
64 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 constant factor in the foreground during a given work period 
 depends in part on the rapidity of work. These results illu- 
 minate the proposition that uninterrupted work is accompanied 
 by muscular inaccuracy which increases at a rate dependent on 
 the rate of activity. When given an industrial interpretation, 
 these results indicate that continued work in the dangerous trades 
 is accompanied during each of the succeeding work periods by 
 increasing chances of accident and at a rate correlative with the 
 speed of work. 
 
 The statistics of the hours when accidents occur (Section V) 
 show complex results. As a basis for conclusions work periods 
 were taken when the factors of "warming up" and "final spurt" 
 are eliminated, when a uniform number of people are at work, 
 and when a fairly uniform degree of speed was maintained. 
 Statistics for such work periods show a regularly and pronounced 
 rise in the number of accidents from hour to hour. If extrane- 
 ous factors are not included statistics of accident-hours indi- 
 cate clearly that fatigue is a cause of industrial accidents. These 
 statistics make possible a description of typical succession of 
 events: (a) the development of fatigue due to monotonous, 
 speeded-up work under a high pressure of mental strain main- 
 tained for long hours at a time; (b) the development of mus- 
 cular inaccuracies due to this increasing fatigue; (c) increasing 
 numbers of accidents due immediately to this increasing loss of 
 muscular accuracy. 
 
 The case against fatigue of overwork is becoming so clear 
 that it is receiving attention in the findings of such a group of 
 men as compose the Interstate Commerce Commission and in the 
 decisions of the conservative courts. Legal authorities have in- 
 dicted fatigue as a cause of accidents and the related decisions 
 have been presented (Section VI) in further defense of the thesis 
 of this investigation. 
 
 In the preceding paragraphs the facts have been summarized 
 upon which the thesis is maintained that fatigue is a cause of 
 industrial accidents. A word of explanation is needed at this 
 point. The accidents which formerly were bulked together and 
 attributed to carelessness now receive a more careful explanation. 
 
EMORY S. BOGARDUS 65 
 
 Dr. Emil Roth says that that which is often ascribed to the care- 
 lessness ("auf das Konto des Leichtsinns und der Nachlassig- 
 keit") of the worker is in reality the result of oncoming fatigue. 1 
 Professor Adams states that this carelessness which has been 
 alleged as a cause of accidents "we are now beginning to realize 
 is often due to the mere stress and strain under which modern fac- 
 tory operatives work." 2 Carelessness is not an ultimate cause, says 
 Elizabeth Butler in her study of Women and the Trades, but a 
 resultant from any one of a multitude of things, one of which 
 is the haste and disregard of personal risk resulting almost in- 
 evitably from a piece-work system. 3 
 
 Crystal Eastman, who has made a study of the causes of those 
 fatal accidents which are commonly spoken t>f as due to the 
 "carelessness of the man injured," says that instead of 95 per 
 cent, only 32 per cent of the fatal accidents can be laid in a 
 measure to the responsibility of the victims ; that of this 32 per 
 cent, 1 1 per cent is not due to carelessness, strictly speaking, but 
 to ignorance, youth, and physical weakness; that in the case of 
 the remaining 21 per cent of the fatalities actually due to care- 
 lessness, some of the men were heedless, some inattentive, and/ 
 some reckless. 4 
 
 For the heedless ones no defense is made. For the inattentive we main- 
 tain that human powers of attention, universally limited, are in their case 
 further limited by the conditions under which the work is done long hours, 
 heat, noise, intense speed. For the reckless ones, we maintain that natural 
 inclination is in their case encouraged and inevitably increased by an occu- 
 pation involving constant risk; recklessness is part of the trade. Not all 
 accidents due to inattention and recklessness can be thus defended; but 
 speaking generally these two kinds of carelessness cannot fairly be called 
 faults of the workman. 
 
 So-called carelessness may be explained by the fact that the 
 fatigued workman is unable to give as close attention to safety 
 appliances and machine guards as a normally resistant workman 
 can give. In their laundry investigation, Clark and Wyatt found 
 
 1 Emil Roth, 14. Intern. Kong., etc., IV, 290. 
 
 a Adams and Summer, Labor Problems (Macmillan, 1908), 483. 
 
 3 Eliz. B. Butler, Women and the Trades (Charities Pub. Com., 1909), 108. 
 
 4 Crystal Eastman, Work Accidents and the Law (Charities Pub. Com., 1910), 95. 
 
66 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 that "each burn is due to carelessness," but that if the girls were 
 to be careful, they would have to focus their minds on self- 
 protection, instead of on the proper accomplishment of their 
 tasks, and would also have to work at a lower rate of speed. 5 
 Hence it is becoming evident that accidents which have been 
 hastily and unscientifically classed as due to "negligence" or to 
 "carelessness" are in reality due to the inexorable demands of 
 the overworked human organism. 
 
 In concluding this summary, it may be added that as soon 
 as it becomes evident that fatigue is a cause of accidents and as 
 soon as the way in which fatigue causes accidents becomes clear, 
 definite methods of prevention must be determined upon and put 
 into operation. /Society cannot afford tQ,_allow its industrial 
 members to submit themselves unduly to the law of fatigue un- 
 dlerlying accidents or to be coercedTby external ~c^Sditions" in a 
 sjmilar__fashipnT' Society cannot afford to permit wage-earners" 
 because of the fatigue effects of long hours of monotonous, 
 speeded-up toil to be destroyed or even to be removed temporarily 
 or permanently as means of support to large families (and the 
 support of these families thus to be thrown upon the public). 
 
 The deaths and disablements due to fatigue represent a need- 
 less waste to society. Louis M. Greeley says that every day the 
 enormous waste to society from industrial accidents becomes 
 clearer, that the burden imposed upon public charity becomes 
 heavier, and that the conviction becomes stronger that our present 
 inaction in these matters must give place to intelligent action in 
 order that these great evils be lessened. 6 
 
 At this point, the question logically follows: What can be 
 done to reduce the fatigue which causes accidents? 7 The 
 answer must be psychological and economic. Make it over- 
 whelmingly to the financial advantage of employers to reduce to 
 the narrowest limits the number of accidents that befall their 
 
 s Clark and Wyatt, "Women Laundry Workers in New York," McClure's, XXXVI, 
 404. 
 
 'L. M. Greeley, "Changing Attitude of the Courts toward Social Legislation," Survey, 
 XXIV, 778. 
 
 7 It will be clear that the defense of the thesis of this investigation does not in itself call 
 for an elaborate discussion of measures for prevention. Consequently, the suggestions made 
 here will be presented only in outline form. 
 
EMORY S. BOGARDUS 67 
 
 employees. 8 The chief way to prevent fatigue-accidents effec- 
 tively is to make the lives and limbs of his employees as impor- 
 tant to an employer as the output. 9 The all-important measure 
 in minimizing fatigue-accidents appears to be compulsory acci- 
 dent-insurance (constitutionality granted, of course). 10 This 
 method of prevention works better than any other in Germany, 
 and is described briefly by Professor Henderson : 
 
 The German industrial-insurance law requires the employers to pay one- 
 third of the cost of sickness-insurance, and all the premiums for accident- 
 insurance; the sickness-insurance fund cares for the disabled workman for 
 thirteen weeks, after which the employers' fund pays for further support 
 during disablement due to accident. Naturally, it is seen to be to the interest 
 of all parties to reduce the number of accidents to the lowest possible level 
 by taking all precautions suggested by experience. If a workingman is 
 careless he may be fined and thus disciplined to observance of the regula- 
 tions made for his benefit. If a certain factory shows a high rate of injury 
 to employees, its assessment is correspondingly raised by the executive com- 
 mittee. The accident-insurance law works automatically to reduce accidents. 11 
 
 (a) It is safe to say that when it becomes financially ad- 
 vantageous to employers to minimize danger of accident to 
 employees they will replace monotonous and speeded-up hand- 
 operations as far as possible by automatic processes. Piece-work 
 in connection with dangerous machines will be supplanted by 
 time-work. Miss Anderson, chief lady inspector in England, 
 says that by cutting down piece-work the danger of accidents 
 will be lessened. In laundries more than one manageress has been 
 able to minimize the risk of accident by insisting on payment by 
 time, not by piece. 12 It follows from the law of fatigue (Sec- 
 
 H. R. Seager, Industrial Insurance (Macmillan, 1910), 28. 
 
 ' Crystal Eastman, op. tit., 106. 
 
 "A problem for investigation arises at this point: What effect has compulsory accident- 
 insurance in Germany had upon the number of accidents per year per thousand ? Adequate 
 data are not at hand whereby a definite answer can be given. The situation is exceedingly 
 complex and many factors would have to be given consideration, some of which may be indi- 
 cated, (i) Year after year employees are speeded up in order to secure an increasing output 
 and a higher accident rate would naturally result from higher rates of speed. (2) During the 
 industrial development of a country, untrained and inexperienced workmen are constantly 
 being added to the force a fact which would tend to increase the accident rate. (3) Stricter 
 control is exercised now than twenty-five or even ten year?-, ago in reporting accidents. Many 
 other factors might be mentioned. 
 
 11 C. R. Henderson, "Wood-Workers and Their Dangers," World To-Day, XXXVI, 976. 
 
 " A. M. Anderson, Sess. Papers (House of Lords, 1004), LIX, 201. 
 
68 RELATION OF FATIGUE TO INDUSTRIAL ACCIDENTS 
 
 tion II), and from the results of the experiments (Section IV), 
 that a reduction in speed would mean a reduction in chances of 
 accident. 
 
 But in many industries a reduction in speed is hardly prac- 
 ticable competition and economic demands are too strong. To 
 reduce speed would seem a retrogression in industry. Where it 
 is impossible to substitute automatic machines, the employer 
 whose employees have been made as valuable to him as his out- 
 put (by compulsory accident-insurance) will lessen the dangers 
 of speed by shortening hours of work. 13 
 
 (b) Under compulsory accident- insurance laws the employer 
 would lessen the danger of accidents by making hours of continu- 
 ous work commensurate with the intensity and danger of the 
 work. Crystal Eastman says that shorter hours an eight-hour 
 day for all railroaders is about the most important thing to 
 reduce the number of accidents. 14 In regard to the employees 
 in the dangerous wire-mills, Miss Eastman says that one way to 
 lessen danger of accident will be "to reduce the hours and shorten 
 the shift." 15 
 
 Greater intensity of work necessitates longer periods of relaxation. If 
 the strain of the work cannot be lessened, the duration must be. Think of 
 the crane man (in the steel-mill) upon whose alertness and care depend the 
 lives of several others. His is a hot, unpleasant, lonely job. There is no 
 one to spell him. He cannot get down from his cab for any reason. And 
 he works twelve hours every day in the year except Christmas and the 
 Fourth of July. No steel company can maintain that it has done everything 
 to prevent accidents until it has reduced the working hours of men in such 
 responsible positions." 
 
 (c) Men and women must not be allowed to work at speeded 
 and dangerous machines according to personal ambition but ac- 
 cording to the physical ability of the given individuals. This norm 
 will be attained not by the methods of the ordinary factory in- 
 spector nor even by medical factory inspection, but ultimately by 
 examinations including tests possibly similar to those described in 
 Section IV in which each individual receives expert attention. 
 The physically unfit for the more dangerous forms of work must 
 be weeded out by expert tests; they must not be allowed as now 
 
 " Crystal Eastman, op. cit., 74. ' Ibid., 33. **Ibid. t 86. "Ibid., 74. 
 
EMORY S. BOGARDUS 69 
 
 to assume the more dangerous forms of work from economic 
 motives and be eliminated by the painful and costly method of 
 accident; for here as elsewhere the law of the survival of the 
 fittest holds. The physical ability (and mental alertness) of the 
 worker and the hours of work must be proportional to the fa- 
 tiguing character and danger of the work. 
 
 (d) Compulsory accident-insurance so regulated that the em- 
 ployee must contribute a certain percentage of the fund from 
 which compensations are paid will enlist the strong forces of 
 labor itself, from individual laborers as such, to the powerful 
 labor unions, in a more successful fight against fatigue and other 
 causes of accidents. When it is made to the financial advantage 
 of both employee and employer to reduce accidents, safety 
 appliances, for example, will be not only installed, but actually 
 used. Employers and employees must use various methods of 
 instructing new and uninitiated workers as to the subtle dangers 
 of fatigue. "Ignorance permits accidents which might be pre- 
 vented." 17 The potential force of the labor union under rational 
 control, as a means of securing education of employees in in- 
 dustrial hygiene, of securing shorter hours and more adequate 
 rest periods, etc., would be aroused to activity if it were made 
 to the financial advantage of the union to do so. The union, 
 made up of the workers themselves, is always present to observe 
 violations, which cannot be the case, for instance, with factory 
 inspectors. 
 
 While a discussion of methods for prevention of fatigue as a 
 cause of accidents does not properly belong here, it is maintained 
 that a method worthy of consideration is compulsory accident- 
 insurance granted the constitutionality of such a procedure, of 
 course. In other words, it is contended that in the prevention of 
 fatigue as a cause of accidents, the will of the employer is pre- 
 eminently important, and the will of the employees expressed 
 through labor unions under rational control is of next importance. 
 
 17 C. R. Henderson, "Social Cost of Accident, Ignorance and Exhaustion," Pamphlet 
 No. 72, National Child Labor Commission (New York, 1908). 
 
 - 
 
14 DAY USE 
 
 RETURN TO DESK FROM WHICH BORROWED 
 
 LOAN DEPT. 
 
 This book is due on the last date stamped below, or 
 
 on the date to which renewed. 
 Renewed books are subject to immediate recall. 
 
 use 
 
 HAR26t960 
 
 
 
 lQjan' fi ?JC 
 
 JAN 
 
 MAY 1 6 1969 
 
 LD 21A-50m-4,'59 
 (A1724slO)476B 
 
 General Library 
 
 University of California 
 
 Berkeley 
 
 26/ff LD 21-50w-l,'J 
 
U.C. BERKELEY LIBRARIES 
 
 CODS2flOtb3