Dr Jasper MacAldin was an eye surgeon working in Belfast, who had lectured on electricity, chemistry and light. Here he is demonstrating an experiment at a time when science could take on the character of sensational entertainment. The device on the table is a thunder house, which showed the impact of electricity. A charge emitted from the jar would cause the little building to fall. The skull is presumably there to suggest the risk involved to human life in the harnessing of the force of nature.