What is that apparatus before the great man, exactly? Here is an abstract from the New York Times, that describes it closely, the very equipment you see before you.
The new transmitter consists of an accumulator battery, an ordinary telegraph key, [and] an induction coil sending an eight-inch spark […] The induction coil is wound, half with thick wire, the two ends of which are connected with the key and battery, and half with thin wire, whose ends are soldered to separate metal rods, each with a large brass sphere at its extremity. … [C]urrent passes from the accumulators … through the thick wire of the coil, and induces a current in the thin one wound over it. The induced current rushes to the brass spheres, and in the form of bluish-tinted sparks leaps the space that intervenes. In this space is hung an ebonite vessel filled with oil and having a brass sphere in each side, opposite to and in a direct line with the two spheres previously mentioned. … [I]t is not unlike a big drum, with a ball stuck half through each parchment side. From this point the electrical waves are sent out … and actuate an instrument that is in electrical harmony with the transmitter.
The receiver is like a wire hoop broken at one point[.] At each side of the break a copper strip stands out, and these form arms for collecting the electrical waves[.] A local battery and a sounder are intervened in the wore hoop, but its current is not strong enough to leap the gap. The waves sent by the transmitter arrive at the copper arms, flow down them, and … pass from one broken end to the other. Each time the waves jump the gap the electrical circuit of the hoop is completed, and the battery current is enabled to cross the break and work the sounder.
“Topics of the Times,” New York Times, May 26, 1897, p. 6.