The book investigates the validity and methodology of psychical research, particularly focusing on spiritualism and mediums. The author, W. J. Crawford, a professor of Mechanical Engineering, approaches the subject with a scientific and empirical mindset, aiming to apply rigorous experimental methods to phenomena often relegated to superstition or belief. He details his experiments, observations, and the apparatus used in an attempt to objectively measure and understand psychic energies and manifestations, challenging both skeptics and proponents to consider the evidence presented.

This work is presented as a significant historical artifact, reproduced from original sources and considered important for the knowledge base of civilization. Its selection by scholars underscores its cultural significance and its role in the preservation of historical scientific inquiry. The text itself is a direct engagement with the scientific investigation of psychical phenomena, reflecting the methodologies and concerns of its time. As a reproduction of a historical artifact, it aims to be true to the original, including any imperfections that may arise from the preservation process.