Not a great deal is known about Stephen Gray. He was born in 1666 and may have been educated, in part, by John Flamsteed (1646-1720), England's first Astronomer Royal. Gray died on February 25, 1736.

Gray became interested in the study of electricity and, in 1729, discovered that rubbing a glass tube caused an electric build-up that extended to a cork that was attached to the end. The cork had not been directly touched, yet the electric "fluid" had gone into it. Furthermore, a pine stick, inserted into the cork, transmitted the electricity to its end.

Experimenting with other substances, he found he could transmit a charge through a thread hanging vertically, but not horizontally unless the thread was suspended by silk. In other words, when he kept the horizontal thread from touching "ground," he could transmit the charge over a good distance.

Gray published his experiments in the Philosophical Transactions, which influenced the work of Charles Du Fay (1698-1739) and John Théophile Desaguliers (1683-1744). Du Fay theorized the existence of "vitreous" and " resinous" electricity, terms that Benjamin Franklin popularized as "positive" and "negative." Desaguliers first coined the word "conductor" to describe an object that transmitted electricity. An object that did not conduct was called an "insulator," based on the Latin word for "island," because an insulator could enclose an electric current just as the ocean could enclose an island.