THE LIGHTING OF FACTORIES, MILLS AND WORKSHOPS BY C. E. CLEWELL In May, 1910, Prof. Chas. F. Scott, Sheffield Scientific School of Yale University, in an editorial in the Electric Journal, made an analysis of the costs of factory lighting in terms of wages, thus emphasizing a new point of view in the consideration of industrial lighting. In the years following, it has become quite common to evaluate factory lighting costs to an equivalent proportion of the wages of the employees who use the light, as one of the best ways of expressing the advantages of good light in factory work. RELATIONS OF ADEQUATE LIGHTING TO FACTORY PRODUCTION Any factory executive or manager should take an interest in those factors which may influence, for good, the production rate of his plant, provided the matter is presented to him in a convincing manner; and he will be found, in many cases, to accept as a working basis for the value of the best lighting to his plant the return in quantity and quality in production resulting directly or indirectly from the expenditure for a modern system of lighting to replace an old and an inadequate system. The value of adequate factory lighting may thus be reduced in a simple manner to such items as the time it saves the employees in the performance of their regular work, the improved accuracy it makes possible in workmanship, the protection and safeguarding of the eyes of the workmen, the beneficial effect of bright and cheerful surroundings on the temperament of those affected, and the tendency it has to reduce accident hazard. If, therefore, in summarizing the advantages of good factory lighting, in contrast to inferior lighting conditions, the cost of improved light be evaluated to the equivalent time saved the employees in the general run of their work, it will be found that the wages thus saved are usually materially greater than the cost of the lighting, and the net saving to the plant, either through reduced wages for the same output, or in larger and better output for given wages, due to improved lighting, is just as definite and important an asset to the plant as is a new machine tool which, due to its higher efficiency in contrast to an older machine, is capable of effecting a similar economy. As a starting point, therefore, it is desirable to assume toward adequate factory lighting an attitude of such a nature as to class it as one of the economies in industrial management; and, rather than to place too much emphasis on the cost of the different available types of lamps or on the various systems of lighting, to concentrate the major part of the attention on the improved quality and quantity of workmanship which may be expected to accompany better lighting. In brief, it is well to think of lighting as an asset to the plant, and, when deciding on the type of lamp to install, to consider which type is best suited to the needs of the factory, rather than to direct all attention, as is so often the case, on those relatively small differences in first cost, which sometimes lead to a selection of the cheapest rather than the best. As a matter of fact, the past five or ten years have witnessed widespread improvements in many factories where the prevailing former conditions were very poor, and a typical factory manager of to-day, whose sections are equipped with modern lighting, is able to take a certain pride in the improved appearance of the surroundings, and at the same time he has the assurance that the accompanying improved workmanship and sentiment of his employees, represent material returns in excess of any outlay he may have been called upon to make for the improvements in question. As obvious as these indirect advantages may seem to be, they are not as satisfying, nor are they as useful in the practical advancement of better lighting conditions in the industries, as would be the case were there more definite examples of cash returns available due to improved light, or were there on record actual numerical percentages of increases in output due to the same cause. The need for such definite information is made evident in a statement by Dean A. J. Rowland, in a discussion on the subject of factory lighting several years ago, part of which follows:1 "There is one very important detail of industrial lighting which seems to have been given but little attention by anyone; that is, the accumulation of data which will give the answer to this question: Is it or is it not worth while to light rooms and machinery correctly and well? "Such questions are as important as any which can be considered in connection with industrial lighting. The kind of lamps used, their 1 Trans. I. E. S., vol. VIII, No. 6, pp. 286 and 287. arrangement, the kind of shades put on them, are insignificant matters compared with the money value of good light to the industries. This will have to be determined somehow if industrial lighting is to come into its own." This quotation from Dean Rowland's discussion is merely given as typical of the impression which prevails that such data are badly needed, and while this need is generally recognized, the data desired are very difficult to obtain, and several quotations from a number of authorities must be taken at this time roughly to indicate the available information on this general phase of the problem. It will be noted that some of these quotations refer to advantages of good light and the disadvantages of bad light, based on features other than those of economy. In a general way, however, they bear directly on the important question as to "Why good light is a necessity?" As an example, the first report of the Departmental Committee on Lighting in Factories and Workshops (London, 1915) contains several comments as follows:3 'Complaints of eye strain, headache, etc., attributed to insufficient lighting are common, and while an exhaustive medical inquiry would be necessary to establish the connection between these defects and inadequate lighting, there is a general impression that unsatisfactory lighting is, in various ways, prejudicial to health. It is also recognized that insufficient light adds to the difficulty of the proper supervision of work, and of the maintenance of cleanliness and sanitary conditions generally. "Witnesses gave specific instances of the effect of improved lighting in increasing the output and improving the quality of work turned out." Again, in the same report, the following statement appears concerning the diminished output of work due to insufficient light:4 "The effect of improved lighting in increasing both the quantity and the quality of the work is generally admitted, and specific instances are quoted in the evidence. In one instance the output was diminished 12 to 20 per cent. during the hours of artificial lighting, and in another the earnings of the workers increased 11.4 per cent. after the installation of a better system of lighting." A clause from one of the Public Health Bulletins of the United States Health Services presents the case from a somewhat different point of view, as follows: ? An experimental investigation is under way at this time to secure definite information concerning the advantages of good factory lighting, the work being planned by the Lighting Committee of the Commonwealth Edison Company of Chicago. 3 Memorandum of British Report, p. 2. Main part of British Report, p. xiii. No. 71, May, 1915, p. 105, J. W. Schereschewsky and D. H. Tuck. "In view of the fact that a large part of the industrial operations in the women's garment trades involve the close and continuous use of the eyes, the illuminating conditions which prevail in the workshops of the industry become highly important from the standpoint of industrial hygiene. The necessity for adequate and correct illumination on the various working planes becomes the more apparent from the consideration of the data in relation to the vision of garment workers contained in the foregoing portion of this report. These data show that only a little over 25 per cent. of the workers whose visual acuity was tested had normal işion in both eyes." Turning now to somewhat more tangible wage equivalents, several good examples are found in a discussion on factory lighting by M. H. Flexner and A. O. Dicker, one of which may be summarized as in Table I. 6 TABLE I Under the assumption that good factory lighting requires a 100-watt tungsten lamp for each 100 sq. ft. of working area, and that one workman occupies each 100 sq. ft., the following statements may be made: These data show that the cost of good lighting is a very small proportion of the value of a man's time; in fact, if good lighting effects a saving of five minutes of a man's time per day, a material gain would be experienced. |