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 where he made many important friends, including the philosopher John Locke. These friends were concerned that such a brilliant mind was not being properly supported. They wanted to find better ways to honor Newton's achievements and ensure he received the recognition he deserved. During his later years, Newton continued to influence science and ideas, leaving a lasting legacy that still matters today.

1693

During 1692–1693, Isaac Newton experienced health problems, including trouble sleeping and digestion. His letters from that time show he felt confused and distant from friends. Scientists later found that Newton’s hair contained high levels of harmful metals like mercury, which may have contributed to his symptoms.

Newton had been interested in alchemy and recorded many experiments with chemicals, including mercury, starting from 1669. In June 1693, he continued these experiments, noting various 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 received this position because of his fame as a scientist and his support of the government during the Glorious Revolution.

Newton took his job very seriously. At the time, the nation’s money was in bad shape because many coins had been illegally cut down or made fake during a war. Newton used his science skills to help fix this problem, leading 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" to help with his discoveries. He kept this method a secret, sharing it only with close friends, because he wanted his new ideas to seem more familiar to everyone else.

Later, in 1693, the method was shared with scientists through the works of John Wallis. Newton’s followers in the Netherlands noticed that others were giving credit to Gottfried Leibniz for a similar method, so they made sure to highlight Newton’s role in creating it. More details about this method appeared in Newton’s book Optics in 1704, along with two extra writings explaining curves and shapes. In 1707, William Whiston published Newton’s algebra lectures, later translated into English.

Bernoulli's mathematical challenge

In June 1696, the mathematician Johann Bernoulli challenged other mathematicians in Europe to solve two difficult problems. One problem was to find the quickest path between two points not in a straight vertical line, called the brachistochrone curve. The other was to find a curve where the sum of distances from a fixed point to two points on the curve would always stay the same.

Newton received these problems and worked quickly. He stayed up late and by the next day had solved both problems. He sent his solutions to the Royal Society to be published anonymously. Even though his name was not used, Bernoulli recognized Newton as the solver from the quality of the work. Later, in 1699, Newton was honored by the French Academy of Sciences for his mathematical achievements.

End of professorship and presidency of the Royal Society

After becoming master of the mint, Newton resigned his professorship at Cambridge in 1701 and appointed William Whiston as his deputy. Later that year, Newton was elected to represent the University of Cambridge in parliament, though he did not keep the position for long.

In 1703, Newton became the president of the Royal Society, a role he held for 25 years—the longest term for any president at that time. During his presidency, he worked closely with Prince George of Denmark, the husband of Queen Anne. In 1705, Queen Anne visited Cambridge and knighted Newton for his contributions to science.

Second edition of the Principia

After the first edition of his book the Principia was published, Isaac Newton started planning a second edition. He wanted to improve it by adding new ideas about how the moon and planets move. However, Newton faced challenges in getting the information he needed from other scientists.

Eventually, with the help of Roger Cotes, a talented young mathematician, Newton began work on the second edition. There was ongoing communication between Newton and Cotes during the printing process. The second edition was finally published in mid-summer 1713. On 27 July, Newton presented a copy of the new edition to Queen Anne. This edition included 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 four 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 managed to solve 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 faced health challenges, including urinary issues and respiratory problems. He moved to Kensington for better care and, despite some improvements, continued to suffer. Newton passed away peacefully in his sleep in 1727. His funeral was held at Westminster Abbey, where he was honored for his contributions to science. His estate was divided among his relatives, and Woolsthorpe Manor, his family home, was later sold.