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on this plan, well-defined shadows

Fig. 10
(cropped from border; squared)
illustrating Silvanus P. Thompson (1851-1916 *), “Electric Shadows and Luminescence.” Proceedings of the Royal Institution of Great Britain / Abstracts of the Discourses Delivered at the Evening Meetings 15 (May 8, 1896) : 191-216
Mayo Clinic / Stanford copy (no date of digitization)

“...it might be possible to produce electric shadows without having resort to any photography. You are aware that if the surface or any part of the surface of a body is electrified, the fact that it is electrified can be ascertained by dusting over it mixed powders of red lead and sulphur (or red lead and lycopodium)... I have succeeded in producing, on this plan, well-defined shadows which will now be demonstrated to you... Fig. 10 is a shadow taken in this way...”

6 June 2016

method; tools; xerography; proto-xerography; S. P. Thompson, “Electric Shadows and Luminescence” (1896)