Abstract: The presence of overlapped sheets on a paper transport is detected by employing such sheets as an acoustic interference filter. A beam of ultrasonic energy of appropriate frequency, angularly oriented to the planar transport path, will be attenuated to a much greater extent than the attenuation calculated based on the attenuation of a single sheet, as a result of destructive combining of wavefronts reflected from the facing surfaces of the overlapped sheets.

Abstract: Apparatus for handling blow molded bottles which are to be transferred from a horizontal position at a lower level to a vertical upright position at a higher level, comprising a plurality of bottle carriers (20), transfer means (22) connected to the carriers for movement of the latter between the lower and higher levels, and arcuate slide members (26) which function to retain the bottles in the carriers as the bottles slide on the slide members during transfer from the lower to the higher level, the slide members terminating immediately prior to the carriers arriving at the higher level so that the bottles can be discharged bottom-first in upright positions at the upper level.