Is it possible that these were used in arc lighting?  At a late nineteenth
century smelter site in Great Falls, we found things that looked like sharpened
battery cores but in fact were carbon(?) rods across which arcs sparked for
lights.  Of course, those rods were about 1/2-inch in diameter, rather than the
smaller rods you describe.

Mitzi Rossillon
Renewable Technologies, Inc.
Butte, America