1. 
   lenticle
   Glass panel in the door of a longcase clock, through which the pendulum may be seen. It is sometimes known as a bull's eye.
   Found op http://www.encyclo.co.uk/visitor-contributions.php
   
   
2. 
   lenticle
   Glass panel in the door of a longcase clock, through which the pendulum may be seen. It is sometimes known as a bull's eye.
   Found op http://www.antique-marks.com/antique-terms-l.html
   
   

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