Those of you who might have studied film-making have likely heard of Ralph Steiner, an influential photographer and documentarian from the 1930s through the 1960s. His work was characterized by use of unusual angles and odd, but beautiful, subjects, some of which were mechanical devices and their workings. One of these is the subject of this month's Discrepancy Sheet: a 1930 short film titled "Mechanical Principles." In 10 minutes, Steiner captures the intelligence and beauty in the design of reciprocating parts, intermeshing gears, eccentric cams and other mechanisms designed to perform their tasks elegantly and repetitively. This short film is a fascinating look at the mechanical world in a pre-solid-state age - view it by clicking here. Some of Steiner's photographs are also on display at New York's Museum of Modern Art.