1 Reference to the original description of the photographic method (Benedict, Am. Journ. Physiol., 1916, 41, p. 275) should be made for the technique of taking these photographs and other details of this method of calculating the surface area.

Comparing the areas for Squad A, as obtained by the photographic method, with those computed from the Du Bois measurements, we find that there are minor variations, but that on the whole the averages of the three measurements show that the total areas as determined by the three methods are essentially alike. The averages for Squad A for September 29 are 1.84,1.79, and 1.83 sq. meters, for the Du Bois formula, height-weight chart, and photographic method, respectively. On November 24, the averages are 1.73, 1.71, and 1.72, respectively. On February 2 the areas computed from the photographs are in most instances smaller than they are by the linear formula, the widest difference being with Gul, 1.72 against 1.63 sq. meters, or 0.09 sq. meter. The average areas for the three methods are 1.73, 1.72 ,and 1.68 sq. meters, respectively.

With Squad B the area computed from the photographic method on January 5 is, in almost every instance, somewhat lower than that obtained by the linear formula, the widest difference being with Sch, 1.84 sq. meters as against 1.75 sq. meters. The averages are 1.84, 1.81, and 1.79 sq. meters. On January 27 a comparison of the two methods likewise shows somewhat lower values with the photographic method than with the Du Bois method. The averages for the three methods are 1.77, 1.77, and 1.72 sq. meters.

Inadditionto the 23 subjects given in tables 18 and 19, a single series of measurements was made with three other subjects, and the body surface obtained by the three methods. These were Fre, on September 29, 1917, McM on January 5, and Lon on January 27, 1918. The values for these three subjects are given in table 20 as supplementary evidence. These values show essentially the same picture as those for the larger group of 23 men.

Table 20. - Body-Surface Measurements, Supplementary Data

We may, perhaps, make the best comparison of the two methods by computing the factor to be used in the photographic method for each date, using the Du Bois linear measurement as the basis. The photographic method, as commonly employed, uses the factor 5.02. With Squad A, the average factor for the first measurement on September 29 would be 5.05. For November 24 it would be 5.03 and for February 2, 5.17. With Squad B the average factor would be, for January 5, 5.19, and for January 27, 5.15.

Since the factor of 5.02, originally derived, was obtained from rather a large number of individuals (20 in all) of grossly varying surface conditions, it is perhaps somewhat surprising that with the more homogeneous material supplied by the subjects in tables 18 and 19, the same average factor is not obtained. Two important points should be considered in this connection, first, that the profile photographs with both Squads A and B were made with artificial light in the laboratory at night, by hanging a large sheet on a frame, and placing behind it an M-type Cooper-Hewitt lamp. This method of illumination was by no means so satisfactory as the daylight method used for the earlier series in which the photographic method was developed and a white sheet was hung before a window. Secondly, the pictures were taken principally to show the general physical contour of these men and not with the special care necessary for their use in accurate photographic measurements, a precaution which should have been taken. Finally, when it is considered that these 12 men were photographed in the nude a few minutes before they entered the respiration chamber at night, and that they were peculiarly sensitive to cold, it will be seen that the photographing was inevitably hastened too much for the best results. Consequently, care was not always taken to place the metric scale exactly opposite the backbone of the subject. Furthermore, it was found necessary to focus the camera on the pedestal upon which the men stood and then take all the photographs without re-focusing for each subject. We believe that these considerations sufficiently explain the variations from the average 5.02 noted in the development of the formula by the photographic method.

As a check upon the Du Bois measurements, however, the photographic measurements are very helpful. Attention should be called to the almost uniform agreement in the Du Bois measurements with Squad A for November 24 and February 2. It is a gratifying verification of these measurements to note that they can be made with a squad of 12 men some 10 weeks apart and still show such uniform agreement with each other. It will be remembered that there was a negligible difference in weight of these men on November 24 and February 2.

Body Temperature

The sensation of cold, which was noted throughout a good part of the research by practically all of the men, made a study of body temperature of special significance. Each morning, prior to the measurements of the respiratory exchange, the oral temperature of the subject was taken with a standard clinical thermometer. These records were made simply to eliminate the possibility of measuring the gaseous exchange when the subject was in a slightly febrile or febrile condition, and not with a view to determining the physiological temperature, for as is well known, mouth temperatures have no definite physiological value.

Throughout the entire series abnormal temperatures were rarely found. Occasionally slightly febrile temperatures were noted when the subject was suffering from a cold; under these conditions the gaseous metabolism was not measured. With Spe abnormal body temperatures were recorded for a number of days prior to his leaving for home in consequence of suspected typhoid infection.