Later Life of Isaac Newton - The Longitude Problem

The Longitude Problem

In 1714 the question of finding the longitude at sea, which had been looked upon as an important one for several years, was brought into prominence by a petition presented to the House of Commons by a number of captains of Her Majesty's ships and merchant ships and of London merchants. The petition was referred to a committee of the House, who called witnesses. Newton appeared before them and gave evidence. He stated that for determining the longitude at sea there had been several projects, true in theory but difficult to execute. He mentioned four:

1. by a watch to keep time exactly
2. by the eclipses of Jupiter's moons
3. by the place of the moon
4. by a new method proposed by Mr Ditton.

Newton criticized all the methods, pointing out their weak points, and it is due mainly to his evidence that the Committee brought in the report which was accepted by the House, and shortly afterwards was converted into a Bill, passed both Houses, and received the royal assent. The report ran "that it is the opinion of this committee that a reward be settled by Parliament upon such person or persons as shall discover a more certain and practicable method of ascertaining the longitude than any yet in practice; and the said reward be proportioned to the degree of exactness to which the said method shall reach."

Newton was a very popular visitor at the Court of George I. The Princess of Wales, Caroline of Ansbach, wife of George II, took every opportunity of conversing with him. Having one day been told by Sir Isaac that he had composed a new system of chronology while he was still resident at Cambridge, she requested him to give her a copy. He accordingly drew up an abstract of the system from his papers, and sent it to the Princess for her own private use; but he afterwards allowed a copy to be made for the Abbé Conti on the express understanding that it should not be communicated to any other person. The abbé, however, lent his copy to M Fréret, an antiquary at Paris, who translated it, and endeavoured to refute it. The translation was printed under the title Abrege de chronologie de M le Chevallier Newton, fait par lui-même et traduit sur le manuscrit anglais.

Upon receiving a copy of this work, Newton printed, in the Philosophical Transactions for 1725, a paper entitled "Remarks on the observations made on a Chronological Index of Sir Isaac Newton, translated into French by the observator, and published at Paris." Newton charged the Abbé with a breach of promise, and answered the objections which Fréret had urged against his system. Father Étienne Souciet entered the field in defence of Fréret; and in consequence of this controversy Newton was induced to prepare his larger work, which was published in 1728, after his death, and entitled The Chronology of Ancient Kingdoms amended, to which is prefixed a short Chronicle from the First Memory of Kings in Europe to the Conquest of Persia by Alexander the Great.