Illustrated Architecture Dictionary
(Leader Heads, Leader Boxes, Collectors, Collector Heads, Conductor Boxes, Catch Basins, Bells, Scupper Heads, and Scupper Boxes)
Besides being ornamental, conductor heads also perform a number of functions. By letting air into the line it helps water drain faster and with less noise; allows the combination of several downspouts into one larger one; acts as a clean out point for debris and also acts as an overflow point for water.
Conductor heads enhance the beauty and architectural style on a building. They are traditionally installed under the soffit.
Hand crafted metal conductor heads are being challenged by polyethylene conductor heads today, although copper and aluminum are popular, also.
Found especially on Tudor Revival and Arts & Crafts buildings.
Examples from Buffalo architecture: