| 摘要 |
In the embodiment depicted and described, the invention comprises a retainer for a sphere, having a sphere captive therein, replaceably attached to the reverse side of a picture frame to cause the frame, automatically, to assume a plumb disposition. The sphere, a round ball, is movable within a track formed in the retainer, and a portion thereof projects from the track for rolling engagement with the surface of a wall from which the frame is suspended. In use, a pair of the ball-retainers are fixed to the reverse side of the frame, at spaced apart locations, with the tracks lying substantially along arcs drawn from a suspension point on the frame which intersects the frame center of gravity.
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