240 



THE INDIA RUBBER WORLD 



January 1, 1921 



light is at least as effective in promoting life and destroying 

 harmful germs as indirect sunlight, or direct sunlight that has 

 passed through glass. From the hygienic standpoint, then, there 

 is nothing against night work in a properly lighted room. 



THE PSYCHOLOGICAL ASPECTS 



And what of the psychological aspects of the. subject? A few 

 years ago such a question would have been ruled out as "high- 

 brow stuflf" by the "practical" works manager. But not so now ; 

 the very obvious fact that the human machine is operated by the 

 brain, and therefore the condition of this controlling apparatus is 

 a matter of prime importance, has filtered into the minds of the 

 whilom scoffers. Electricians tell us that the amount of electricity 

 that you can obtain from a given connection is directly propor- 



RELAnoN OF Industrial Accidents to Illumin.\tion 

 A ^^,^XIMuM OF Accidents Occl-r During Novemker. December and 



jANirABY, THE MoNTHS OF MINIMUM r>AVLlGHT 



tional to the electromotive force at the source, and inversely 

 proportional to the resistance of the conductor. This may serve 

 as an analogy by which to describe the effect of the mind upon 

 the worker. The "electromotive force" is the necessity for 

 him to make his living — the fear of "losing his job"; the "resist- 

 ance" is his natural laziness, the irksomeness of labor as such. 

 The output of any individual worker will depend upon these two 

 forces. 



The effect of a greatly reduced "labor-motive force" resulting 

 from the shortage of workmen is still a very vivid memory in 

 the minds of employers. How to reduce the resistance, the innate 

 repugnance to work, is the most serious problem confronting the 

 efficiency engineer and the scientific manager today. To supply 

 incentive, to create interest, to inspire enthusiasm, to relieve 

 tedium, in short, to increase the will to work, are subjects which 

 fall within the domain of modern psychology. Aside from the 

 ancient prejudice of the worker against night labor, the fact is 

 that night offers better conditions for work ; there are fewer dis- 

 tractions, and less heat in summer. 



That there are sociological problems involved is evidenced by 

 the fact that at least one of the great manufacturing states has 

 a law against night work by women, and strenuous efforts have 

 been made to introduce such laws into Xew York State. 



THE ECONOMIC ASPECTS 



Little argument is needed to .show the economic advantages 

 which night work presents. The difference between profit and 

 loss in manufacturing may often be solely a question of the 

 overhead expense. Interest, taxes, insurance, and depreciation of 

 plant make up the larger part of the fixed charges. Double shift 

 meant cutting this in half, and triple shift, or continuous opera- 

 tion, cutting in thirds, prorated to output. To build and equip 



new factories to be idle half or two-thirds of the time is an 

 unpardonable sin against efficiency and economy. Aaequate and 

 proper electric lighting is capable of doubling the value of the 

 total investment in manufacturing plants throughout the world, 

 measured by their producing capacity. 



But the economic importance of artificial lighting is not con- 

 fined to the strictly night-shift operation. Daylight is insufficient 

 for maximum production for a considerable portion of the time 

 of the 8-hour day shift, totaled for the year. There are dark 

 days in the winter, dark mornings and afternoons in spring and 

 fall, and many rooms that are naturally dark at any time. In 

 one of the most up-to-date automobile plants I recently saw 

 hundreds of electric lamps burning on a bright autumn day. To 

 have tlie production kept up in both quantity and quality regard- 

 less of the vagaries of the weather, or changes of season, is a 

 manifest wisdom to a manufacturer who would thrive, — to keep 

 at the top in those trying periods when the weaker go to the wall. 

 Any loss in production due to inadequate lighting is an absolutely 

 needless waste. 



COST OF ARTIFICIAL LIGHTING 



The cost of artificial lighting is a matter that can be disposed 

 of with very little discussion. Light is the one facility that most 

 directly affects the output of the human machine. Its results 

 vary from zero, or nothing, in total darkness, to 100 per cent in 

 proper illumination. A light that reduces the output 10 per cent 

 is equivalent to a 10 per cent raise in wages. The only logical 

 method of figuring the cost of light is therefore to equate it 

 with wages. In one tire plant, which may serve as an example, 

 the cost of electric light was two cents for an average size tire. 

 A curious case is that of a very large automobile plant, in which 

 the cost of washing the windows is equal to the cost of all the 

 electric light used, and the plant regularly runs continuously. A 

 little arithmetic will show how the matter stands. Suppose a 

 workman is receiving a wage of 60 cents an hour, which is one 

 cent a minute. Suppose the cost of electric current is one cent 

 per unit (k.w.h.). One minute of wages is then equal to one 

 unit of current, or 1,000 warts, for one hour, or 100 watts for 10 

 hours. One minute of wages, therefore, will pay for the current 

 for a 100-watt lamp for a ten-hour day. Current, however, is 

 not the whole cost of the light ; there are the other items of 

 lamps, accessories, and upkeep. All of these should not exceed 

 the cost of the current. One minute of wages may then be con- 

 sidered equal to the entire cost of light from a SO-watt lamp for 

 a 10-hour day, or a 60-watt lamp for 8 hours. This would be 

 ample for work in a fixed position ; but if general illumination 

 were required where the work or machines were more or less 

 widely separated, two, or even three times this amount might be 

 required. 



We may, therefore, say that the loss of from one to three 

 minutes of a workman's time will balance the cost of a 100 per 

 cent light for his whole working day. Economy is good manage- 

 ment, the most profitable proportioning of outgo to income. Can 

 there be any worse economy than a failure to supply the best 

 possible light for the workman? 



LESSENS SHOP ACCIDENTS 



There is one collateral branch of the subject of the economics 

 of lighting which is of importance, and that is its' relation to 

 industrial accidents. Some ten years ago a fairly comprehensive 

 compilation of statistics showed that 25 per cent of industrial 

 accidents were due to faulty fighting. Recent statistics indicate 

 that but 15 p<;'r cent are now traceable to this source. This is a 

 gratifying improvement, but it is still exactly IS per cent too 

 many. With the present cheapness and ease with which ample 

 light for safety can be supplied, there is no excuse for failure in 

 this regard. Avoidable accidents to the human machine are not 

 good economy. 



