Re: Where's Homer Simpson...inanimate carbon rod?
they ARE carbon core rods for dry cell batteries. The one with the ridges is just a variation to give more surface area for the chemical reaction. As to the question of size, don't be thinking on the line of AA C or D cells, though they too have a carbon core, but it is more the size of a ciggarette, these are LARGE dry cells, think along the line of 6 volt lantern battery, only they were only 1.5 volts, on some of the carbon rods you may be able to see the remains of the brass threaded rod that was one of the connection points for battery. I have found them 'glued' together with tar to make up bigger cells with higher voltage. From what I am told they were likely used to power early radio sets.