Experiments in psychical science : levitation, contact, and the direct voice
A 1919 London and New York parapsychology study by W. J. Crawford, published by Watkins and E. P. Dutton, recording experiments on levitation and contact phenomena for a readership interested in psychical research. The pictures are plain line diagrams of apparatus: a table T, a lever or pivot marked M, springs and labelled points, drawn in black on white with arrows showing force direction, a clean schematic style a designer could borrow for technical infographics.
