Gray S

Name: Stephen Gray

Achievements: Electricity

Born: 1666; Canterbury, England

Died: February 15, 1736; London, England (Aged 70)

Field & Discipline: Science; Electricity

Language: English

Father: Unknown

Mother: Unknown

Siblings: Unknown

Spouse: Unknown

Children: Unknown

Education: Unknown

Major Work:

“A Letter….Containing Several Experiments Concerning Electricity” (1732)

Life & Times:

Little is known about Gray’s life.  It is possible that he studied in London, or perhaps Greenwich, under the Astronomer Royal [taught by] Flamsteed* who, like Gray, was the son of a tradesman, and whom Gray addressed in letters as his ‘honoured friend’. Certainly Gray developed a knowledge of optics and astronomy, and had a contact at the Royal Society who sent him the “Philosophical Transactions” of the Society. His contact also passed on to the editor of the “Transactions” letters from Gray, who was still living in his native town of Canterbury.

In 1696 the Society published his first paper in which he described making a microscope from a drop of water held in a hole in a brass plate. He followed this up with reports of his observations on magnetic sands and fossils. From around 1703 he began recording data about phenomena like sunspots, eclipses and, with the aim of developing navigational techniques,  the revolutions of Jupiter’s satellites. Gray’s work was respected and Flamsteed used some of his results.

A demonstration to the Royal Society by [inspired by] Hauksbee* in 1706 on the creation of an electric force in a tube of rubbed glass inspired Gray to experiment in Cambridge during 1707-8,  when he spent several months as an adviser on a project for a new observatory.

 In these experiments he replicated [replicated work of] Guericke’s* discovery that a feather drawn across the surface of a glass tube electrified by friction will then float above the tube. He also discovered that luminosity was related to electric force and he theorized that electrically-induced movement and light were caused by two streams of fine particles, one generated by electricity and one (in response) from the surrounding atmosphere.

He sent his findings to the Royal Society but they were not printed because they were referred to Hauksbee who then himself started demonstrating the phenomena Gray described.

The observatory project in Cambridge did not materialize and Gray returned to Canterbury.  In 1711 he asked [asked help from] Sloane*, the secretary of the Royal Society, for help in his experiments.  

In 1719 Sloane succeeded in getting Gray taken in at the London Charterhouse as a ‘gentleman pensioner’.

It is not known whether Gray read the writings of [may have studied] William Gilbert*  who was the first to classify substances as either electric or non-electric,  but in  1720 Gray announced to the Royal Society that he had discovered a new class of non-rigid electric substances which included hair, silk, feathers, and gilded ox guts.

His next note to the Society came nine years later. He had failed in his attempt to electrify metals by friction and hoped to do so by exposing them to what he termed ‘effluvia’ from a rubbed glass tube sealed with two corks. By chance he applied a feather to one end of the tube and found it was attracted to the cork, not the glass. He decided that the electrified glass had communicated its excited state to the cork.

He then transmitted an electric force from an activated cork through threads or sticks to various other objects including a tea kettle and an ivory ball. He succeeded in transmitting fifty-two feet. Luckily he had a wealthy friend who owned a large country house where there were much longer drops available to hang his thread. There, Gray transmitted an electric force, what he called the ‘virtue’, through silk threads over hundreds of feet. However, when he replaced the silk threads with a brass wire, nothing happened.  He had accidentally discovered insulators and conductors.

Over the next two and half  years Gray and his friends worked on transmitting electricity, building up a list of substances which worked as insulators or conductors. They were not able to account for most of their results but their experiments paved the way for developments such as the Leyden jar by [paved way for] Petrus van Musschenbroek*.

Gray published his findings in 1732 and was at last made a member of the Royal Society. He made a few more observations on sparks and on the way electrified objects kept their state for much longer when they were enclosed in tight, dry boxes.

Extra Connections: He lodged with [lodged with] Desaguliers*

Assessment: Paved the way for advances in electrical science.

Oneliner: Stephen Grey, early electricity pioneer

Bibliography:

• Dictionary of National Biography.
• Dictionary of Scientific Biography.

Stephen Gray (scientist) - Wikipedia