This late 1920s-early 1930s frame-mounted General Electric Oil Circuit Breaker is part of an industrial/commercial substation in Shawnee, Oklahoma owned and operated by Oklahoma Gas & Electric. Note the amber colored expansion chambers on the peaks of the bushing terminals. The amber glass is not amber because of the oil, as many people believe, but is the actual cast glass color of these chamber containers. They are about 1/4" in thickness and about 8-12" high. As the oil expands under heat, the breakers' reservoir of oil is forced up into the internal bushing wells. Sometimes these breakers are supplied with capacitance-style bushings, accounting for their signficant girth. These appear (from an observer's point-of-view) to be solid-fill style bushings.