ORANGE-RED UNDERWEAR. 535 



opinion was that the colored clothing was heavier and caused more per- 

 spiration than the white. 



The special underwear was given a trial by sixteen officers. In a 

 majority of cases it was discarded after a short time because its weight was 

 greater than that usually worn and it was therefore much hotter. This 

 objection induced the members of this Board to have the nainsook under- 

 wear, as sold by the quartermaster department, dyed by a local dyer to the 

 same color as the special clothing. This was an improvement, but the 

 writer could see no advantage in the colored clothing over the white of a 

 similar weight. Only one unqualified expression of approval came from 

 these officers, and this was from one who stated that he always had 

 experienced a feeling of depression of spirits and irritation after ex- 

 posure to the sun previous to wearing the colored underwear, but that 

 this had been relieved entirely by its use. He was convinced that it 

 was the proper clothing for use in the sun, but added that it kept him 

 slightly warmer than did the white. 



EXPERIMENTAL EVIDENCE. 



It can be accepted without question that a fabric of red or orange-red 

 color is highly protective against those chemical rays of the sun which 

 reduce the photographic plate. Other colors have varying degrees of 

 protective influence, but all are protective to some extent. However, 

 the protection afforded by a fabric depends not only on its color, but 

 upon its thickness and the tightness of its weave. A great deal of in- 

 formation has been obtained by exposing to sunlight photographic plates 

 covered by fabrics from the different articles of the uniform. By 

 adding to these fabrics layers of the colored and white underwear and 

 the orange-red hat linings, a good idea was obtained as to the increased 

 protection from the actinic rays of the sum afforded by the colored 

 garments. The most interesting result is that the campaign hat, two 

 varieties of which were used, is as opaque to chemical rays without a red 

 lining as with it. The lining materially added to the opacity of the 

 khaki cap, and showed a slight improvement over the ordinary lining 

 of a green or brown color as seen in the caps bought of the military 

 supply houses. 



A comparison of the English and American khaki shows that the 

 added weight and tighter weave of the latter increased the degree of 

 protection afforded against the rays which reduce the photographic plate 

 when the exposure was as short as could be made with the slide shutter. 

 A longer exposure of the English khaki with the colored and white 

 undershirt shows what a material difference in opacity the orange-red 

 color produces. The same kind of experiments were made, using material 

 from the blue flannel shirt, the olive-drab shirt, and the blue chambray 

 shirt in the same manner. Not much would be expected from the cham- 



