manently crippling disorders. In other cases the application of simple corrective or palliative measures may greatly increase the industrial efficiency of the individual. If the defects are not remediable, their detection will at all events prevent the choice of unsuitable occupations, and will indicate desirable lines of education.

In rural communities, undoubtedly one of the simplest, as well as most important, health protective measures is the adoption, under compulsion if need be, of a safeguarded and standardized form of barrel privy. A corollary hardly necessary to mention is the total abolition of the privy in all thickly settled towns. For lack of such regulations soil pollution occurs, the house fly finds an opportunity to transfer disease germs from excreta to food, and typhoid fever and hookworm disease become constant plagues over wide regions.

In the campaign against tuberculosis it is perhaps too early to evaluate the numerous methods that have been proposed for lessening or eradicating this disease, but it is already evident that some are more directly repaying than others in proportion to the effort involved. Among the methods for which public funds are legitimately available none is more promising than the provision of sanatoria for advanced cases of consumption. Newsholme and Koch have shown that the general diminution in the death rate from tuberculosis observed in most countries in recent years can be more reasonably attributed to the establishment of sanatoria than to any other factor, and that in addition to its humanitarian advantages, the segregation and proper control of the advanced and dangerously infective cases is one of the most useful methods that can be employed by the community to protect itself against the spread of tuberculous infection.

Another field in which practical workers are convinced that certain measures have direct efficacy in saving life is that of infant mortality. It has even been said that for the expenditure of a certain sum the saving of a life can be guaranteed. Certain it is that in few public health activities is the ratio between effort expended and results obtained so clearly seen. No one doubts to-day that prompt notification of births, education of the mother through any one of a number of agencies, and special provision for suitable feeding of infants during hot weather are factors that are bound to tell powerfully in the reduction of infant mortality. It may confidently be asserted that the degree of success achieved in this field will be limited only by the amount of endeavor the community is willing to put forth.

It is impossible at present to apply direct tests of efficiency to some measures that undoubtedly promote health. The influence of playgrounds, public baths, regulation of the hours of labor in extra

1 See Public Health Reports for 1910, published by the Public Health and Marine-Hospital Service. articles by Stiles and Gardner, and Lumsden, Roberts. and Stiles.

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arduous industries and the like is real, if it can not be accurately determined or estimated. Certain activities of a health department may be worth continuing for their educational value, although their direct utility may be questioned. Many topics need investigation in order to discover their real bearing upon the public health. Among these are such matters as the effect of a smoky atmosphere, the alleged nervous strain due to city noise, and numerous important questions in the domain of food adulteration and contamination. Premature and drastic action by health authorities in matters concerning which there is profound disagreement among experts may cast discredit on other lines of activity in which there is and can be no difference of opinion.

For the present it seems worth while to emphasize more sharply than heretofore the distinction between public health measures of proved value and those that owe their existence to tradition or to misdirected and uninformed enthusiasm. Further study of the results obtained by certain of the usual and conventional health department activities is also much needed, and as a preliminary to such study the proper collection and handling of vital statistics is essential. It is poor management and unscientific procedure to continue to work blindly in matters pertaining to the public health, to employ measures of whose real efficiency we are ignorant, and even to refrain from collecting facts that might throw light upon their efficiency.

FACTORY SANITATION AND EFFICIENCY.1

By C.-E. A. WINSLOW.2

It may fairly be maintained that in most industries the largest element invested is what may be called life capital. For example, in the cotton industry in 1905 there was invested a capital of $613,000,000, while the pay roll amounted to $96,000,000 a year. Capitalized at 5 per cent, this pay roll would correspond to an investment of $1,920,000,000 in the form of the hands and brains of the workers. The calculation is perhaps a fanciful one, but it illustrates the fundamental fact that the human element in industry is of large practical importance. Particularly in regions like New England, where there is no wealth of natural resources, prosperity depends on a skilled and intelligent operative class. Such a class Massachusetts has had in the past and the present interest in industrial education testifies to the conviction that the efficiency of the operative must be improved to the highest possible degree.

Once the operative is trained and at work it is generally assumed that the results obtained will depend only on his intrinsic qualities of intelligence and skill. The effect of the environment upon him is commonly ignored; but its practical importance is very great. In industries where it has been shown that the machine which makes a given fabric requires certain conditions of temperature and moisture for its successful operation these conditions are maintained with exemplary care. In every factory, however, there is another type of machine, the living machine, which is extraordinarily responsive to slight changes in the conditions which surround it. These conditions, in this relation, we habitually neglect.

I am not dealing now with the sociological and humanitarian aspects of the case. I am quite frankly and coldly, for the moment, treating the operative as a factor in production whose efficiency should be raised to the highest pitch, for his own sake, for that of his employer and for the welfare of the community at large.

The intimate relation between the conditions which surround the living machine and its efficiency is matter of common experience with

1 Reprinted by permission from Technology and Efficiency. Proceedings of the Congress of Technology at Boston Apr. 10, 1911. pp. 442-448. Copyright 1911, by McGraw-Hill Book Co.

Associate professor of biology, College of the City of New York, and curator of public health, American Museum of Natural History, New York City.

us all. Contrast your feelings and your effectiveness on a close, hot, muggy day in August and on a cool, brisk, bright October morning. Many a factory operative is kept at the August level by an August atmosphere all through the winter months. He works listlessly, he half accomplishes his task, he breaks and wastes the property and the material entrusted to his care. If he works by the day the loss to the employer is direct; if he works by the piece the burden of interest on extra machinery has just as truly to be borne. At the close of the day the operative passes from an overcrowded, overheated workroom into the chill night air. His vitality lowered by the atmosphere in which he has lived, he falls a pray to minor illness, cold and grip, and the disturbing effect of absences is added to inefficiency. Back of it all lurks tuberculosis, the great social and industrial disease which lays its heavy death tax upon the whole community after the industry has borne its more direct penalty of subnormal vitality and actual illness.

The remedy for all this is not simply ventilation in the ordinary sense in which we have come to understand the term. Mr. R. W. Gilbert, of the Massachusetts Institute of Technology, begins a suggestive paper on "The economics of factory ventilation," in the Engineering Magazine for December last, as follows:

Webster's definition of the word ventilation is "to air" or "to replace foul air by fresh." In actual practice, however, ventilation should mean more than this. It should mean the conditioning of the air of any inclosed space to the best requirements of the occupants of that space.

Conditioning of the air so that the human machine may work under the most favorable conditions--this is one of the chief elements of industrial efficiency, as it is of individual health and happiness.

The chief factors in air conditioning for the living machine, the factors which in most cases far outweigh all others put together, are the temperature and humidity of the air. In many a plant after spending money for an elaborate system of ventilation, the air has been kept too hot or too dry or too moist, and the effect on comfort and efficiency has been worse than nil. It is a curious instance of the way in which we neglect the obvious practical things and attend to remote and theoretical ones, that for years more attention has been bestowed on the testing of air for carbon dioxide, which was supposed to indicate some mysterious danger, than on the actual concrete effect of overheating. Yet heat, and particularly heat combined with excessive humidity, is the one condition in air that has been proved beyond a doubt to be universally a cause of discomfort, inefficiency, and disease. Flügge and his pupils in Germany and Haldane in England have shown that when the temperature rises to 80° with moderate humidity or much above 70° with high humidity, depres

1

1 The literature on this subject is well summarized with references to original sources by T. R. Crowder in "A study of the ventilation of sleeping cars," Archives of Internal Medicine, vol. 7, p. 85.

sion, headache, dizziness, and the other symptoms associated with badly ventilated rooms begin to manifest themselves. At 78° with saturated air Haldane found that the temperature of the body itself began to rise. The wonderful heat-regulating mechanism which enables us to adjust ourselves to our environment had broken down and an actual state of fever had set in. Overheating and excess of moisture is the very worst condition existing in the atmosphere and the very commonest.

The importance of the chemical impurities in the air has dwindled rapidly with the investigations of recent years. The common index of vitiation, due either to human beings or to lighting and heating appliances, is carbon dioxide; but carbon dioxide in itself has no harmful effects in tenfold the concentration it ever reaches in ordinary factory air. Nor is there any reduction of oxygen which has any physiological significance. In the Black Hole of Calcutta and below the battened-down hatches of the ship Londonderry there was actual suffocation due to oxygen starvation, but this can never occur under normal conditions of habitation. It was long believed that the carbon dioxide was an index of some subtle and mysterious "crowd poison" or "morbific matter." All attempts to prove the existence of such poisons have incontinently failed. There are very perceptible odors in an ill-ventilated room, due to decomposing organic matter on the bodies, in the mouths, and on the clothes of the occupants. These odors may exert an unfavorable psychical effect upon the sensitively organized, but as a rule they are not noticed by those in the room, but only by those who enter it from a fresher atmosphere. Careful laboratory experiments have quite failed to demonstrate any unfavorable effects from rebreathed air if the surrounding temperature is kept at a proper level. In exhaustive experiments by Benedict and Milner (Bulletin 136, Office of Experiment Stations, U. S. Department of Agriculture), 17 different subjects were kept for periods varying from 2 hours to 13 days in a small chamber with a capacity of 189 cubic feet in which the air was changed only slowly while the temperature was kept down from outside. The amount of carbon dioxide was usually over 35 parts (or eight to nine times the normal), and during the day when the subject was active it was over 100 parts, and at one time it reached 240 parts. Yet there was no perceptible injurious effect.

The main point in air conditioning is, then, the maintenance of a low temperature and of a humidity not too excessive. For maximum efficiency the temperature should never pass 70° F., and the humidity should not be above 70 per cent of saturation. At the same time a too low humidity should also be avoided. We have little exact information upon this point, but it is a matter of common knowledge with many persons that very dry air, especially at 70° or over, is excessively stimulating and produces nervousness and discomfort. It would