The present invention relates to a conveyor that includes at least one dogging device. Preferably, the mirror elements have different widths to provide a tapering appearance and reduced weight during transport. The relative motion is a superposition of a first continuous component of motion provided by the first motion provider and a second, smaller component of motion provided by the second motion provider which lessens the velocity of the at least one image relative to the camera, during imaging. Fuel mixture and exhaust apparatus is connected to one end of the engine to feed a fuel mixture to the increasing-volume chambers and extract the exhaust from other decreasing-volume chambers.