268 THE SCIENTIFIC MONTHLY
constant flicker, or to a rapid alternation of light and dark. In some of the needle trades the needles in the machines move so rapidly that it is impossible for the operator to watch them directly for the purpose of controlling the machine; there is therefore suspended above the machine a strong electric light which shines into the eye of the worker as well as upon the needles; and she must watch the flickering reflection constantly.
The fact tiiat most factories are noisy places is a serious one for the worker. It has been found by experiment that the constant noise produces an imdesirable effect upon the nervous system of the worker, as well as upon his physical efficiency. In the presence of the noise the body tires more easily, and the monotony and rhythm of the noise have a tendency to dull the mind — ^very much like mother's lullaby. However, some of us are much more sensitive to these effects than others, and if you advertise for boiler-makers you will no doubt receive a number of applicants.
The posture in which the work is carried on is important. In many trades it is practically impossible to produce maximum results except in a standing position; and when you are paid by the piece, that is to be considered. In other trades various kinds of stooping and bending are required, although the scientific manager is gradually changing ma- chinery and processes to avoid such awkward situations — it has been found more productive to avoid stooping. The modern builder does not aUow his bricklayers to bend over for the brick and mortar; since 6il- breth showed that the output of the worker could be doubled by means of his special platforms and motion system, the bricklayer may hold his body erect all day long. While walking is considered to be "good exer- cise, there are some people who should not become letter-carriers; while sitting is often "very restful, there are many men and women who are not constitutionally able to thrive in a sedentary occupation.
People inclined to rheumatism should avoid occupations in which one must be much on a wet floor, as in certain chemical shops, or in slaughter houses. In some processes the worker must expose the skin to the action of various chemicals that are more or less injurious. Some skins are so sensitive that they find the relatively mild chemicals used in photography exceedingly irritating.
The question of accidents should not be overlooked. In some occu- pations daily accidents are accepted as a matter of course; in others they are exceedingly rare. In the steel industry alone there is consid- erable variation. If we take all the workers in that industry for whom records were available in 1910, we find that the accident rate was 245.!^ per thousand workers (allowing 300 days of work to the year). Of these 2.72 per thousand resulted in permanent injuries, while 1.86 acci- dents were fatal. Now in the puddling process the rate for the same
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