Smog measuring device, 1950
Caption slip reads: "Photographer: Forbes. Date: 1950-11-27. Reporter: Harrison. Assignment: Smog measuring device. 23-24: Walter J. Hamming, research coordinator for control district, with continuous sampler of particulate matter, deposited on revolving filters at left. 45-46: Anthony Bellin, left, chemist, with continuous sampler used to test for sulfuric acid mist. 123-124: Stanley Hall, engineer with A.L. Chaney Laboratory, checks new continuous visibility recorder".