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48 CLOTHING TEST METHODS Finally, the third controllable variable is exposure temperature. If the mitten combination provides protection for 90 minutes at rest with the clothing specified at minus 40°F., the breakdown point will come in a shorter time at colder temperatures, 80 minutes probably at minus 50°F., and at a longer interval, 100 minutes, at minus 30°F. There are other factors which influence tolerance time in addition to the degree of exercise, clothing worn over the remainder of the body and exposure temperature. These factors are more difficult to recognize and evaluate and for practical purposes may be neglected. In this discussion it has been tacitly assumed that at subzero tempera- tures, tolerance times must be taken into account since no clothing or other gear is adequate for Indefinite periods of time under all conditions. Throughout the exposure, from the beginning of the experiment until the breakdown point, the body is slowly losing heat and the margin of reserve becomes smaller and smaller. Even though it may appear that the mittens break down at 90 minutes when the hand becomes unbearably cold, this statement does not- do justice to the facts. The mitten is providing only relative protection throughout the exposure period. Changes may be introduced to lengthen or shorten the tolerance time but unless something is done to prevent inevitable loss of body heat, there comes a time when intolerance appears. Exercise and additional clothing may be but temporary ex- pedients and do not necessarily prevent further heat loss or restore the heat already dissipated. It Is reasonable to inquire how reproducible are tolerance times. In trained subjects, accustomed to the cold room, the results from subject to subject and from day to day are consistent and satisfactory. Some subjects have consis- tently longer tolerance times and appear to be more resistant to the cold than the average. Other subjects have shorter tolerance times and appear more sus- ceptible to the cold. The majority of subjects tested show neither a resistant nor a susceptible reaction to the cold and fall in the average group. Because tolerance times for a given item of clothing under controlled conditions give reproducible results, the data obtained may be transposed into performance in the field, either maneuvers or combat. If it can be stated to the Commanding General that this mitten combination keeps a soldier from being frost- bitten for a 90-minute period at rest at minus 40°F., it is a tangible statement. It is based solely upon subjective evidence but the expression is in everyday understandable units. If tolerance times for all items of clothing are known it is of great help in planning the total clothing for a soldier and in approximating the possibilities and limitations of performance in the field.
GRADING OF SENSATION John H. Talbott It is highly desirable that a schema for grading sensations be establirhed. Sufficient work has now been done in the various laboratories in this country and in Canada to establish such a schema. Once it is agreed upon by interested parties it is hoped that it will be adopted widely. The proposed differentiation may be applied generally and should not be restricted to any one field of testing, such as ccld-room or hot-room testing. It may be applied in fields already explored, such as cold, heat, fire, poisonous and obnoxious gases, decompression sickness, diminished oxygen pressure, mechani- cal trauma, fatigue, dietary deficiency, exposure and immersion, among others. The proposed system is sufficiently elastic that it may be applied in realms of testing not yet explored. The schema is based upon function and should find its greatest applica- tion in the interpretation of laboratory testing and transposition of laboratory and controlled field testing into field operations. The grade assigned comprises the specific level of usefulness and function under the various conditions imposed upon the item. The grades are as follows: Grade 0 This includes the comfort range but does not exclude awareness of the stimulus. Examples. High Temperature. The subject is aware that the ambient temperature is above the optimal comfort range, but discomfort has not developed. ⢠Obnoxious Gases. The subject smells the gas or otherwise is aware of its presence but suffers in no way from it. Mechanical Trauma. The subject is aware that a suit of underwear is rubbing the skin but no irritation or damage to the skin has appeared. Grade I The sensation of the stimulus has progressed to severe discomfort or mild pain but the ability to carry out the mission or the function for which the item was devised is not impaired. Examples. Low Temperature. The fingers of a subject are uncomfortably cold but they may be partially warmed by exercise and the firing of a rifle is not appreciably affected. Decompression Sickness. Onset of mild pain. Subject can move about and perform functions necessary for protection in a bomber as before the onset of pain. Exposure. The victim on the life raft has a moderate sunburn. This is uncomfortable, but the mission can still be carried out. Signalling devices can be used, rowing can be done effectively and .fresh water can be prepared, since the mission on a life raft is to stay alive and to be rescued.
