James Clerk Maxwell 
Electrical Researches of the Honorable Henry Cavendish 

Henry Cavendish (1731-1810), the grandson of the second duke of Devonshire, wrote papers on electrical topics for the Royal Society, but the majority of his electrical experiments did not become known until they were collected and published by James Clerk Maxwell a century later, in 1879, long after other scientists had been credited with the same results. Among Cavendish’s discoveries were the concept of electric potential, which he called the ‘degree of electrification’; an early unit of capacitance, that of a sphere one inch in diameter; the formula for the capacitance of a plate capacitor; the concept of the dielectric constant of a material; the relationship between electric potential and current, now called Ohm’s Law; laws for the division of current in parallel circuits, now attributed to Charles Wheatstone; and the inverse square law of variation of electric force with distance, now called Coulomb’s Law.