278 Newton, Isaac Dr Isaac Barrow, Lucasian Professor of Mathematics at Cambridge, became his mentor and brought out Newton’s genius Avoiding the Plague Newton returned to his mother’s farm to avoid the plague rampant in Cambridge from 1665 to 1666 Without access to his books, Newton discovered differential calculus, which he called “direct and inverse method of fluxions,” and expansions into infinite series He used common arithmetical elements to make them universals Newton also queried the nature of gravity but realized his experiments required more work and left the problem until 1685 Upon his return to Cambridge in 1667, Newton was shown the work of Nikolaus Mercator (1620–87), who had recently published Logarithmotechnia This contained some of the methods Newton had used while experimenting on the farm Newton showed Barrow his own ideas, and this work was published as De analysi per aequationes numero terminorum inifitas in 1711 After painstaking experiments in 1668, Newton discovered the spectrum, which he deduced was white light made up of colored lights when exposed to a transparent medium This idea led Newton to perfect a reflecting telescope in 1668; it was six inches long and could magnify 30 times Prior to Newton’s telescope, only refracting telescopes were used Barrow resigned from Cambridge, and Newton obtained the Lucasian Chair in 1669 at age 27 after he earned a master’s degree He presented lectures on optics that were not published until 1728 By this time, Newton’s work was noticed by such scientific luminaries as Robert Hooke, Christiaan Huygens, James Gregory, and Sir Christoper Wren among others Newton became a fellow of the Royal Society in 1671 Controversy erupted over claims by Hooke, who was a powerhouse at the Royal Society, that he was first to invent the “pocket tube” (telescope) in 1664 Gregory the Scot claimed he had discovered calculus Newton removed himself from the controversy and only published his work Opticks in 1704 after Hooke died Newton suffered a mental breakdown in 1675; it took him four years to recover He then found mathematical proof of planetary ellipses around the Sun Hooke had also realized these laws but failed to prove them Edmund Halley (1656–1742), the astronomer and mathematician, met with Newton in 1684 Halley urged him to publish his findings and financed the book entitled Philosphiae naturalis principia mathematica, better known as Principia, which included his three laws of motion The third book of Principia appeared in 1687 and turned the natural sciences upside down Newton’s theories were taught at Edinburgh by his disciple David Gregory and Cartesian theory was dropped at Cambridge and Oxford; the French would not accede to Newton’s theories until 50 years later Newton grew tired of life at Cambridge, so he embarked on a career of public service in 1687 He became a member of Parliament for Cambridge University in 1689 He had another nervous breakdown in 1696 Upon recovering, Newton accepted the job of warden of the Mint in London He was promoted to master in 1699 and revised Britain’s coinage Newton was reelected to Parliament in 1701 but soon lost interest in the position He became president of the Royal Society in 1703, a position to which he was reelected for 25 years He was a tyrannical and autocratic president who had favorites and made life torturous for those who dared to disagree with him Queen Anne knighted him in 1705 controversies Newton was engaged in two major scientific controversies The first was from 1705 to 1712 with Astronomer Royal John Flamsteed (1646–1719), whose notes Newton conspired to publish against Flamsteed’s wishes The second was from 1704 to 1724 with Gottfried Wilhelm von Leibniz (1646–1726), a German mathematician Leibniz claimed he had discovered calculus before Reproduction of rough sketch by Isaac Newton showing a reflecting telescope and its components