the Greek word for "amber". Gilbert undertook a number of careful electrical experiments, in the course of which he discovered that many substances other than amber, such as sulphur, wax, glass, etc., were capable of manifesting electrical properties. Gilbert discovered that a heated body lost its electricity and that moisture prevented the electrification of all bodies. He noticed that electrified substances attracted all other substances indiscriminately, whereas a magnet only attracted iron. The many discoveries of this nature earned Gilbert the title founder of the electrical science. By investigating the forces on a light metallic needle, balanced on a point, he extended the list of electric bodies and found that many substances, including metals and natural magnets, showed no attractive forces when rubbed. He noticed that dry weather with north or east wind was the most favourable atmospheric condition for exhibiting electric phenomena—an observation liable to misconception until the difference between conductor and insulator was understood. Robert Boyle worked frequently at the new science of electricity and added several substances to Gilbert's list of electrics. He left a detailed account of his researches under the title of Experiments on the Origin of Electricity. In 1675 Boyle stated that electric attraction and repulsion can act across a vacuum. One of his important discoveries was that electrified bodies in a vacuum would attract light substances, this indicating that the electrical effect did not depend upon the air as a medium. This was followed in 1660 by Otto von Guericke, who invented an early electrostatic generator. By the end of the 17th century, researchers had developed practical means of generating electricity by friction with an electrostatic generator, but the development of electrostatic machines did not begin in earnest until the 18th century when they became fundamental instruments in the studies about the science of electricity. The first usage of the word electricity is ascribed to Thomas Browne in his 1646 work Pseudodoxia Epidemica. In 1729 Stephen Gray demonstrated that electricity could be "transmitted" through metal filaments. Mechanical devices As an aid to scientific investigation, various tools, measuring aids and calculating devices were developed in this period. Calculating devices John Napier introduced logarithms as a powerful mathematical tool. With the help of Henry Briggs their logarithmic tables embodied a computational advance that made calculations by hand much quicker. His Napier's bones used a set of numbered rods as a multiplication tool using the system