Later life of Isaac Newton

Isaac Newton was one of the greatest scientists who ever lived. After publishing his famous work called the Principia, he moved to London. There he made many important friends, including the philosopher John Locke. These friends cared about Newton and wanted to make sure he was respected for his great work. During his later years, Newton kept influencing science and ideas. His work still matters a lot today.

1693

In 1692–1693, Isaac Newton had health problems, like trouble sleeping and digestion. His letters from this time show he felt confused and far from his friends. Scientists later learned that Newton’s hair had high levels of harmful metals, such as mercury. This may have caused some of his health problems.

Newton was very interested in alchemy. He recorded many experiments with chemicals, including mercury, beginning in 1669. In June 1693, he kept doing these experiments and wrote about the effects of the metals he tested.

Running the Royal Mint

For 30 years, Isaac Newton worked at the Royal Mint as both warden and Master of the Mint. He got this job because he was famous as a scientist and supported the government during the Glorious Revolution.

Newton took his job very seriously. At that time, the nation’s money was in bad shape because many coins had been changed or made fake. Newton used his science skills to help fix this problem. He led a big effort to remake all the nation’s coins. Later, he became Master of the Mint, a job that paid very well. He used his knowledge to catch people who made fake coins and helped create a new system for the nation’s money.

Fluxions

Main article: Fluxions

Before publishing his famous work the Principia in 1687, Isaac Newton used a special math method called the "method of fluxions" for his discoveries. He kept this method a secret and shared it only with close friends. He did this so his new ideas would seem more familiar to everyone.

In 1693, the method was shared with scientists through the works of John Wallis. Newton’s followers in the Netherlands saw that others were giving credit to Gottfried Leibniz for a similar method. They made sure to show Newton’s role in creating it. More details about this method appeared in Newton’s book Optics in 1704. In 1707, William Whiston published Newton’s algebra lectures, which were later translated into English.

Bernoulli's mathematical challenge

In June 1696, the mathematician Johann Bernoulli asked other mathematicians in Europe to solve two hard problems. One problem was to find the quickest path between two points that were not in a straight vertical line, called the brachistochrone curve. The other was to find a curve where the total distance from a fixed point to two points on the curve would always be the same.

Newton got these problems and worked very fast. He stayed up late and by the next day, he had solved both problems. He sent his answers to the Royal Society to be published without using his name. Even without his name, Bernoulli knew it was Newton's work because of how well it was done. Later, in 1699, Newton was honored by the French Academy of Sciences for his math work.

End of professorship and presidency of the Royal Society

After becoming master of the mint, Newton stopped his job as a teacher at Cambridge in 1701 and chose William Whiston to help him. Later that year, Newton was chosen to be a member of parliament for the University of Cambridge, but he did not stay in this job for long.

In 1703, Newton became the leader of the Royal Society. He stayed in this job for 25 years, which was the longest time anyone had been the leader at that time. During this time, he worked with Prince George of Denmark, who was married to Queen Anne. In 1705, Queen Anne visited Cambridge and gave Newton a special honor called a knighthood for his work in science.

Second edition of the Principia

After the first edition of his book the Principia was published, Isaac Newton planned a second edition. He wanted to add new ideas about how the moon and planets move. However, Newton had trouble getting the information he needed from other scientists.

With the help of Roger Cotes, a talented young mathematician, Newton started work on the second edition. Newton and Cotes talked often during the printing. The second edition was published in mid-summer 1713. On 27 July, Newton gave a copy of the new edition to Queen Anne. This edition had improvements and new experiments to support Newton's theories.

The longitude problem

In 1714, finding the longitude at sea became very important. Many ship captains and merchants asked the government for help. Newton spoke to a committee and talked about ways to find longitude, but he pointed out problems with each one.

Because of Newton's evidence, the government decided to offer a reward for a better way to find longitude. Newton led the Board of Longitude, which gave money to mathematicians like Leonhard Euler to work on this problem. Although some think John Harrison, who made special clocks, deserved the reward, his clocks did not change how ships sailed at the time. Newton remained a favorite at the court of King George I, and even worked on special dating systems of history at the request of the Princess of Wales, Caroline of Ansbach, wife of George II.

Theological studies

Isaac Newton spent a lot of time studying religion. He began these studies before 1690 and even solved tough math problems while doing so. In 1690, he wrote a letter about important parts of the Bible, but decided not to publish it right away because it challenged some common beliefs.

Newton also wrote about the prophecies in the Book of Daniel and the Book of Revelation. He created a dictionary to explain special measurements used in ancient Jewish times. He also wrote letters discussing proofs for the existence of a god, along with other historical and religious works.

Final years

In his final years, Isaac Newton had health problems, including urinary and breathing issues. He moved to Kensington to get better care. Newton died peacefully in his sleep in 1727. His funeral was held at Westminster Abbey, where he was honored for his work in science. His home, Woolsthorpe Manor, was later sold.