“1. One is by a watch to keep time exactly; but by reason of the motion of the ship, the variation of heat and cold, wet or dry, and the difference of gravity in different latitudes, such a watch hath not yet been made.
“2. Another is by the eclipses of Jupiter’s satellites; but by reason of the length of telescopes requisite to observe them, and the motion of a ship at sea, those eclipses cannot yet be there observed.
“3. A third is by the place of the moon; but her theory is not yet exact enough for that purpose; it is exact enough to determine the longitude within two or three degrees, but not within a degree.
“4. A fourth is Mr. Ditton’s project, and this is rather for keeping an account of the longitude at sea than for finding it, if at any time it should be lost, as it may easily be in cloudy weather. How far this is practicable, and with what charge, they that are skilled in sea affairs are best able to judge. In sailing by this method, whenever they are to pass over very deep seas, they must sail due east or west; they must first sail into the latitude of the next place to which they are going beyond it, and then keep due east or west till they come at that place. In the first three ways there must be a watch regulated by a spring, and rectified every visible sunrise and sunset, to tell the hour of the day or night. In the fourth way such a watch is not necessary. In the first way there must be two watches, this and the other above mentioned. In any of the first three ways, it may be of some service to find the longitude within a degree, and of much more service to find it within forty minutes, or half a degree if it may, and the success may deserve rewards accordingly. In the fourth way, it is easier to enable seamen to know their distance and bearing from the shore 40, 60, or 80 miles off, than to cross the seas; and some part of the reward may be given when the first is performed on the coast of Great Britain for the safety of ships coming home; and the rest when seamen shall be enabled to sail to an assigned remote harbour without losing their longitude if it may be.”
The committee brought up their report on the 11th June, and recommended that a bill should be introduced into parliament for the purpose of rewarding inventions or discoveries connected with the determination of the longitude. The bill passed the House of Commons on the 3d July, and was agreed to by the Lords on the 8th of the same month.[91]
In giving an account of this transaction,[92] Mr. Whiston states, that nobody understood Sir Isaac’s paper, and that after sitting down he obstinately kept silence, though he was much pressed to explain himself more distinctly. At last, seeing that the scheme was likely to be rejected, Whiston ventured to say that Sir Isaac did not wish to explain more through fear of compromising himself, but that he really approved of the plan. Sir Isaac, he goes on to say, repeated word for word what Whiston had said. This is the part of Mr. Newton’s conduct which M. Biot has described as puerile, and “tending to confirm the fact of the aberration of his intellect in 1693.” Before we can admit such a censure we must be satisfied with the correctness of Whiston’s statement. Newton’s paper is perfectly intelligible, and we may easily understand how he might have approved of Mr. Ditton’s plan as ingenious and practicable under particular circumstances, though he did not think it of that paramount importance which would have authorized the House of Commons to distinguish it by a parliamentary reward. The conflict between public duty and a disposition to promote the interests of Mr. Whiston and Mr. Ditton was no doubt the cause of that embarrassment of manner which the former of these mathematicians has so unkindly brought before the public.
CHAPTER XV.
Respect in which Newton was held at the Court of George I.—The Princess of Wales delighted with his Conversation—Leibnitz endeavours to prejudice the Princess against Sir Isaac and Locke—Controversy occasioned by his Conduct—The Princess obtains a Manuscript Abstract of his System of Chronology—The Abbé Conti is, at her request, allowed to take a Copy of it on the promise of Secresy—He prints it surreptitiously in French, accompanied with a Refutation by M. Freret—Sir Isaac’s Defence of his System—Father Souciet attacks it—and is answered by Dr. Halley—Sir Isaac’s larger Work on Chronology published after his Death—Opinions respecting it—Sir Isaac’s Paper on the Form of the most ancient Year.