Popular Science Monthly
which appears as heat and some of which appears as motion. The body can be thought of as an engine with steam up, with the fires constantly burning while life lasts.
This fire keeps the body very close to a temperature around 98 or 99 degrees Fahrenheit, which is much above the average outdoor temperature.
Now with the fire con- stantly burning, it is evi- dent that heat is con- tinually being given off. Through the lungs the gaseous products of combustion, carbon di- oxide (and along with this a good deal of oxy- gen also, for the body uses only a part of the oxygen that is breathed in), are also constantly thrown off. But the body keeps its temperature con stant by means of a wonder- fully complicated temperature control system.
The Commission set about studying the effect of • the various factors of the air on this heat eliminating, gas producing, human engine by placing people, as shown in one of the accompanying pic- tures, in a specially built ex- periment chamber, a room connected with steam coils, a refrigerating plant, moisture producing apparatus, ventil- ating fans and various other devices for altering the condi- tion of the air. The great advantage of this experiment chamber over the ordinary room is that each of the various air factors — temperature, moisture, etc. — can be controlled and varied at will. . In a crowded theater, for instance, .as the air gets warmer it also gets more moist and begins to have a "crowd" odor. In the experiment chamber the temperature can be hotter while the moisture remains the same, or the moisture can be increased while keeping the temperature the same. In this way each of these various factors can be separated and studied independently.
The Commission paid people regular salaries to stay irt this experiment chamber. First these people, or subjects, would be exposed to one condition for a day or a
���Measuring the size of the breathing spaces in the nostrils by breathing gently on a cold metal plate
���The overheated air in the room has caused the bone in one nostril to swell
��week and then to another. They wrote down on paper just how they felt. But their opinions on personal comfort were not sufficient. It is also desirable to know whether people can do better work under one condition than they can under another, not merely physical work, but mental work. And are they as healthy in one condition as they are in another? Is it variations in temperature that have the greatest influence on health and efficiency? Is it variations in mois- ture?
Nearly four years have been spent in getting the answers to these most important questions. Over two hundred different peo- ple — men and women, col- lege students, clerks, typists, truck drivers, boiler makers, firemen, the robust and the weak, the large and the small, the clean and the unclean, have spent some portion of their time — from one day to six weeks — within the experi- ment chamber. To observe and study the effects of the various air factors on these subjects the Commission has employed a corp of trained observers, — psychologists, physicians, physiologists, chemists, sanitarians, bacteri- ologists, and engineers who have recorded with scientific exactness each shade of differ- ence observed in the separate individuals.
The Findings of the Jury of Specialists
In the first place, they have found that so long as the room was kept cool, that so long as the temperature was not allowed to rise, it did not make much difference whether or not a plentiful supply of fresh air was supplied to the chamber.
Even when the subjects spent a whole day and six days in succession in the unaired chamber, breathing air that con- tained the accumulated products of the breath, they did as good mental work, felt just as happy, and did as much physical work as they did when the ventilating fans were constantly changing the air. Further- more, the most careful observations of the