In this photograph, taken by a photographer of the Chemical Warfare Service's Research Division, Clark is conducting mechanical research. The image shows an American Tissot mask, including features such as a die casting with a chin rest, inhalation tubes, a flutter valve and guard, and a breathing tube. The mask is seen assembled in position. The date of the photograph is July 12, 1918.

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Size: 8484px × 5809px
Photo credit: © piemags/NSC / Alamy / Afripics
License: Licensed
Model Released: No

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