Glass, metal, and wood; Box: H. 13 in. (33.0 cm), W. 14 in. (35.6 cm), L. 18 in. (45.7 cm); jars: H. 12 1/4 in. (31.2 cm), Diam. 2 in. (5.0 cm)
American Philosophical Society (Philadelphia, Pa.), 58-36
The individual Leyden jar, the early form of what is now called a capacitor, gathers an electrical charge and stores it until it is discharged. Franklin grouped a number of jars into what he described as a "battery" (using the military term for weapons functioning together). By multiplying the number of holding vessels, a stronger charge could be stored, and more power would be available on discharge.