Saturday, July 14, 2012

A Wire to Connect the World - Stephen Gray's Discovery

In a famous experiment Stephen Gray demonstrated static electricity
by charging a boy suspended by insulating strings in 1744
Today for us it's pretty normal that electricity can be transmitted on a wire, because it's part of our daily life. But, in the early 18th century, when the English nature-scientist Stephen Gray was able to show that electricity really can be transmitted on a string of copper, it was an unheard-of revelation.

Gray was born in Canterbury, Kent in 1666 and after some basic schooling, he was apprenticed to his father in the cloth-dyeing trade. His interests, however, lay with natural science and particularly with astronomy, and he managed to educate himself in these developing disciplines, mainly through wealthy friends in the district who gave him access to their libraries and scientific instruments. Science was very much a rich-man's hobby at this time.

In 1696 he published an account of a magnifying glass that interested the Royal Society and from then on he frequently sent the Society and his patron, English Astronomer Royal John Flamsteed, ideas for simple but revealing experiments and reports of geological and astronomical observations. But John Flamsteed, the first Astronomer Royal, was one of Sir Isaac Newton's fiercest rivals. As some believe this led to Newton (by then president of the Royal Society) blocking the publishing of several of Gray's papers on electricity later on.


Stephen Gray was pursuing a long series of experiments with electricity. In producing charge on a long glass tube, he discovered in 1729 that he could communicate the electrical effect to other objects by direct connection. Using string, he could charge an object over 50 feet from the rubbed tube, but oddly enough some other substances, such as silk thread, would not carry charge. Brass wire would transmit charge even better. These experiments with charged strings and glass tubes revealed the properties of conduction, insulation, and transmission.

The depiction above shows one of Gray's most famous experiments, in which he showed that a boy suspended by (insulating) silk cords could be charged (with the glass tube) and then as a (conducting) body could (electrostatically) attract small objects. Dramatic experiments such as these became quite well-known. Finally, after Newton's death in 1732, Gray was admitted as a member of the Royal Society in recognition of his efforts, but he died destitute a few years later in 1736.

At yovisto you can learn how to transmit electricity even without any wire simply through the air. Eric Giler wants to untangle our wired lives with cable-free electric power.



References and further Reading:
Post a Comment