Envelope reads "Hetch Hetchy Mitchell tunnel explosion 1930." Photograph shows four men seated on a bench or bed. The two men in the middle lean against eachother and and the men on each end sit with their elbows on their knees. The men in the center of the frame wear work clothes. The man on the left wears a suit, and the man on the right wears a shirt, vest, and necktie. For more information about the Mitchell explosion see h99.1.482.