Abstract: To determine whether stress cracks are present in the bottom area of a plastic bottle which make it unfit for further use, the bottle bottom is scanned in the potential crack region by the measuring beam of a laser distance-measuring instrument. From its output signal, the prevalence and depth of the cracks can be identified sufficiently to enable a decision to be made on the removal of the bottle from circulation.

Abstract: The apparatus serves for rapid orientation of a periscope and, if desired, a weapon barrel with respect to a sighted target. A contact potentiometer is proved as angle transmitter for an electric servo control. The contact potentiometer is annularly arranged around the observer's post at the vehicle, preferably in the region of the rim portion of the observation hatch of the vehicle. The contact potentiometer comprises an arcuate, hose-like insulating envelope defining a radial direction. A resistance track and a contact track are laid within the insulating envelope at a predeterminate spacing therebetween in the radial direction of the insulating envelope. By touching the contact potentiometer in the direction of sight, there is tapped thereat a resistance value corresponding to the direction with which the periscope or, if desired, the weapon barrel has to be aligned by a swivelling motion.