ALVAN CLARK HERSCHEL WEDGE

This is an original Alvan Clark Herschel Wedge. The excess light is dissipated as heat, and goes out the holes at the end. Some of the newer wedges I have seen simply allow the excess light to exit either downward or from the end of the tube - anyone passing by or looking in that direction could get an eyefull of concentrated sunlight. I would think that the newer Herschel wedges could be modified to make them safe.