"Principles of Electricity " Maynard Shipley, 1924 (No. 722 - Little Blue Book)
 
These educational guides provide a window into the scientific understanding of the 1920s, bridging the gap between foundational physics and speculative biological theories. They explain the core principles of magnetism, electrostatics, and the then-emerging electron theory of matter, while also exploring the radical idea that electrical energy is the literal "vital force" governing heart rhythms, nerve signals, and the broader evolution of living organisms. By demystifying complex concepts like high-frequency discharges and atomic structure, these pocket-sized manuals sought to replace traditional mythology with an empirical, albeit early, view of the universe and the human body as sophisticated electrical systems.