Illustration depicting an Electric Machine, or a device used to convert mechanical energy into electrical energy to store a static positive charge. The device operates by turning a glass plate between two metal-coated "rubbers" to produce an electrical charge. The illustration is labeled to identify components of the device including the conductors, crosspiece, and curved rods.

This plate is found in the publication, Wonders of Electricity and the Elements, an educational volume covering a variety of topics related to electricity and the chemical elements in two parts. The first half of the volume is devoted to electrical and magnetic discoveries and modern electric machines, including the telegraph, while the second half explores the elements through the categories of metals, bases, salts, and acids. The volume is profusely illustrated throughout, including many illustrations depicting a range of scientific experiments and electrical machinery. An extensive listing of other Ward, Lock & Co. publications completes the volume.