At the abandoned Greenhill Mine in Crowsnest Pass, four large air compressors stand in the ramshackle remains of a building, part of which had completely collapsed at one point and has none been removed from the site. Each pair of compressors was driven by a single electric motor, with a large stator / rotor assembly on a drive shaft midway between the two compressors. Originally their intended purpose was to drive air belowground for use by the coal miners. They are now partly dismantled by the removal of the copper windings and other parts; the motors have been silent since the 1950’s. But for someone interested in studies of line and light aboveground, these abandoned devices can still exert a powerful magnetic attraction for hours on end.