referring now to the drawings , and especially to fig1 , an apparatus for orienting lightweight articles , such as , plastic bottles , sometimes referred to as an unscrambler , is shown therein generally indicated by numeral 18 . unscrambler 18 is a specific embodiment of the present invention and in this instance is used to orient and align conventional lightweight plastic bottles or containers generally identified by numeral 19 . the bottles are typically used for holding water or soft drinks . each of the bottles has a conventional construction including a rounded body 20 and a longitudinal axis along the length of the body with a bottom 21 on one end of the axis and an open neck 22 at the opposite end of the axis . unscrambler 18 generally includes a frame 23 which has a horizontal drum axle 24 rotatably mounted in the frame . a drum or wheel 26 is secured to the axle so that the drum rotates in a continuous 360 ° circular drum path about a horizontal drum axis of rotation . as viewed in fig2 , the uppermost portion or top of the circular drum path is identified by numeral 27 , and the lowermost portion or bottom is identified by numeral 28 . for purposes of identification of positions along the drum path , the top is identified as 0 ° ( or 360 °) with increasing numbers in the direction of rotation of the wheel so that the bottom is at 180 °. the numbers identifying positions of the drive continue from the bottom to complete the 360 ° at the top . a conventional drive assembly 29 drives the axle from a conventional power source which is not shown herein . the drum has an interior loading portion 30 and an exterior discharge portion 32 . the interior loading portion includes a continuous outer peripheral wall 34 with a plurality of slats 35 mounted on the interior of the peripheral wall to form identical alignment troughs 36 . the alignment troughs rotate in a trough path with the drum about the horizontal drum axis of rotation . each of the troughs 36 has a longitudinal trough axis parallel to the horizontal axis of rotation . each trough has a width which is slightly greater than the width of each of the bottles . the length of each of the troughs is sufficient to receive more than one bottle in the trough . peripheral wall 34 of the drum has a plurality of apertures 38 contained therein communicating with the troughs so that all troughs have apertures . bottles 19 to be aligned by the unscrambler are carried on a chute 40 and fall into the drum in a random fashion such as that shown in fig4 . the drum is continuously rotated and the bottles tumble within the drum and are retained within the drum by a sidewall 42 . some of the bottles fall into respective troughs with the article axis of the bottle aligned with the trough axis . as the drum rotates , the troughs move in a circular trough path so that a trough in the bottom position of the drum , that is , 180 ° is moved upward toward the uppermost portion 360 °. any bottles which are not secure in a trough moving toward uppermost portion 27 tumble back down toward the lowermost portion of the drum to seek positioning in a succeeding trough . when a trough is positioned 15 ° past the horizontal , that is , at 285 °, the trough is positioned in an area covered by a plenum or hood 43 . a conventional source for evacuating air is connected to the hood . the source evacuates air from the troughs through apertures 38 in the peripheral wall of the drum . the flow of air from the interior of the drum into the troughs and out of the troughs through the apertures holds bottles in respective troughs under the hood . the hood extends 30 ° past the top so that the bottles are held in place in respective troughs through an arc of 105 °, which arc is identified as arc b in fig1 . looking now to fig6 , a pivotal trough shelf 44 has a curved retaining surface 45 conforming to the trough path . the retaining surface is positioned adjacent to the innermost surface of the slats forming the troughs to retain the bottles in the troughs moving past shelf 44 . retaining surface 45 extends from a position 25 ° from the top to a position 105 ° from the top , and is identified as arc c in fig1 and 17 . there is an overlap of 5 ° wherein air pulled into the hood retains bottles in the troughs and shelf 44 also prevents the bottles from leaving respective troughs thereby reducing the likelihood of a mishap . shelf 44 is mounted on a shelf shaft 46 which allows shelf 44 to pivot in the event that a bottle is retained inward toward the interior of the drum outside of a trough as it approaches the shelf . the offending bottle displaces the shelf by pivoting the shelf on the shaft as shown in dotted form in fig6 to prevent damage to the unscrambler or a jamming the bottle between the shelf and the slats . shelf 44 by means of a conventional detent not shown is returned to its intended operative position once the offending bottle in engagement with the shelf is released . the bottles contained in the troughs are retained in the troughs by shelf 44 until the troughs move to a position 15 ° below the horizontal , that is , 105 ° from the top . the bottles retained in the troughs by shelf 44 are free to move axially along the length of the respective trough . each of the troughs has an air propulsion aperture 48 aligned with the length of the trough on the loading side of sidewall 42 . a pair of pressure manifolds 50 is positioned adjacent to the loading side of the sidewall to cover temporarily each aperture 48 as the drum rotates as shown in fig8 and 9 . air under pressure from a conventional blower 52 is forced through the propulsion apertures into respective troughs . the air under pressure pushes a bottle in a trough axially along the length of the trough into holding receiver 54 fixed to the end of each trough . the bottle is moved from the holding receiver to an inversion chute 56 fixed to and aligned with each holding receiver . the chutes rotate in a chute path with the rotation of the drum . the drum includes a discharge wall 57 defining a portion of the holding receiver . a plurality of exit apertures 58 is formed in the discharge wall with an exit aperture aligned with each holding receiver . a plurality of radial sidewalls 60 is mounted on the discharge wall . as may be seen in fig5 , the radial sidewalls are radially set about the axle of the drum and each sidewall is positioned between the adjacent exit apertures . each radial sidewall 60 consists of a generally trapezoidal hopper wall 62 and a generally rectangular stall wall 64 as shown in fig1 and 11 . a radial stall shelf 66 and a radial unloading shelf 68 are mounted on frame 23 . a compartment wall 70 is secured to the stall shelf and the unloading shelf . the compartment wall includes an inclined outer hopper portion 72 and an integral stall portion 74 . bottles contained in the respective chutes are kept in the outermost side of the chute due to gravity as the bottles move from 105 ° toward the lowermost portion of the drum path and then upward toward the 255 ° position in a path identified as arc d in fig1 . a fixed chute shelf 76 extends from 15 ° below the horizontal , that is 255 °, to 30 ° from the top , that is , 330 °, identified as arc e in fig1 . thus , the bottles are contained in their respective chutes until a position 30 ° before the top or 330 °. the compartment wall covers the radial sidewalls from 330 ° to 180 °. when a bottle in a respective chute reaches the end of chute shelf 76 , the bottle drops through an alignment aperture 78 in chute floor 80 into a hopper 82 defined by trapezoidal hopper walls of a pair of adjacent radial sidewalls 60 , the discharge wall 57 and the inclined outer hopper portion of the compartment wall . an air nozzle 84 is positioned above the chute path to provide an air stream and thereby assist the bottle &# 39 ; s passage through the alignment aperture . it is immaterial as to whether the bottle enters the chute neck first or bottom first . aperture 78 has a body opening 86 with neck openings 88 and 90 at opposite ends of opening 86 . as may be seen in fig1 and 14 , if the bottle enters the chute neck first , the neck falls down through opening 88 so that the bottle falls neck first . however , if the bottle enters the chute bottom first , as shown in fig1 and 15 , the neck of the bottle falls down through opening 90 so that the neck is down first . in either case , the bottle falls neck first from the hopper to a radial stall 92 communicating with the hopper . each radial stall is formed by adjacent rectangular stall walls of adjacent radial sidewalls , the discharge wall , and the stall portion of the compartment wall . the stall with its radial sidewalls is perpendicular to the horizontal drum axis of rotation . the bottle slides down the stall into engagement with stall shelf 66 . the movement of the bottle from the chute to the stall shelf occurs in 60 ° of rotation of the drum and is identified as arc f in fig1 . the stall shelf extends from 30 ° to the top , that is , 330 ° to 15 ° past the horizontal , that is , 105 ° identified as arc g in fig1 . unloading shelf 68 extends from a position 15 ° above the horizontal , that is , 75 ° to 15 ° past the bottom , that is , 195 °. the unloading shelf overlaps the stall shelf by 30 °, as shown in fig5 and 17 . the arc of the unloading shelf is identified as arc h in fig1 . as may be best seen in fig5 , a given bottle leaves its chute 56 and enters its radial stall 92 through the hopper 82 and rests on stall shelf 66 in an inverted attitude , that is , neck down . the rotation of the drum carries the bottle to a juncture of the stall shelf and the unloading shelf . once the bottle passes the 90 ° point of the drum , gravity and the centrifugal force caused by the rotation of the bottle with the drum causes the bottom of the bottle to have a firm engagement with unloading shelf 68 . the bottle reaches the lowermost portion or 180 ° in a vertical neck up attitude in a steady state . a conventional starwheel 94 is mounted adjacent to the exterior portion of the drum at the bottom of the drum path rotation where the compartment wall ends to allow bottles to be extracted from the stalls . the bottles contained in the stalls in a stable upright attitude are engaged by starwheel 94 and carried to a conventional discharge conveyor 96 to be delivered in a continuous upright line of bottles . the present unscrambler allows the bottles to move from a random arrangement to an attitude where the bottles are aligned in troughs 36 with the longitudinal axis of the bottles aligned with the horizontal axis of rotation of drum . the bottles are moved longitudinally in the trough to a respective inversion chute 56 . the bottles are allowed to reach a state of equilibrium after the longitudinal movement in the respective trough . the longitudinal axis of the bottle in the chute is parallel to the horizontal axis of rotation of the drum . discharge of the bottle from the chute changes the attitude of the bottle to one in which its longitudinal axis is perpendicular to the axis of rotation of the drum . each of the bottles is held in the changed attitude to allow each of the bottles to achieve a steady state . the force of gravity plus the centrifugal force generated by the rotation of the drum tends to keep the bottle in an attitude perpendicular to the axis of rotation of the drum and thereby effects a steady upright position for each bottle to be delivered to star wheel 94 and then to discharge conveyor 96 to be carried away in an inline upright attitude . although the invention has been described in detail above , it is readily apparent that those skilled in the art may make various modifications and changes in the instant invention without departing from the spirit and scope of the present invention . it is to be expressly understood that the scope of the instant invention is limited only by the appended claims .