In one article of IEEE Spectrum, the picture number 2 shows the head set. It is mentioned like this:
HEAD CASE: Today’s electromedical researchers are busy mapping the brain, but 19th-century electrical engineers were already on the case. This electrical phrenology apparatus consists of two parts, a headpiece and a wooden box containing a sledge induction coil and three batteries. The headpiece forms a crown 23 centimeters (9 inches) in diameter with 13 brass electrodes evenly spaced across it.
From the picture, we can see the early research of Brain-Machine Interface. Well, it is not really a machine since the function is unknown. For more information about the history of Phrenology can be seen from their website.