Twin Carbon Elements of Bunsen Cell

Two "L" shaped metal bars and two wooden frames. The "L" shaped bars are attached by a semi-circular hinge with a screw at either end fixing it to the bars. Each bar has two slots for carbon rods, there is one complete carbon rod and one partial attached to the bars. The two wooden frames are painted red and have metal screws at the top. One of the frames has two carbon elements fitted to the frame by the metal screws, between the elements is a stiff card-like board. The other frame has only the card board and a metal screw at the top, no elements.