The Life of Dr. Robert Hooke.

Dr. Hooke, by leaving this invention undiscovered until the end of his life, gave some people cause to question whether he ever truly possessed it. They doubted whether a theory that seemed very promising would hold up when put to the test of practice. Others judged him more harshly, asserting that it was merely a boast to claim knowledge of something that had not yet been accomplished, even though many had attempted it. Whatever the truth of the matter, it is certain that he persisted in this claim to the very end. Not many weeks before his death, he told me and others that he knew a certain and infallible method to discover the true position of a ship at sea regarding its distance east or west from the port of departure. Whether this was by watches, other timekeepers, or some other method, I do not know—though, based on what was mentioned earlier, it seems to have been by watches, for the improvement of which he conducted many trials and wrote several discourses.

However, this matter led to the discovery of the most useful and practical method of regulating pocket watches by a spiral spring, applied to the arbor of the balance, just as they are made today without any significant changes since. The history of this, as I heard it from him and as I find it published, is as follows:

In conversation once, he told me that around the year 1660, having shown a movement so regulated to Lord Brouncker and others (as related above), Monsieur Huygens—who had for some time been applying himself to inventing various ways to regulate timekeepers through his correspondence with Mr. Oldenburg—had received notice of this, for which an application for a patent was later made. This is possible, but whether it was so or not, I cannot determine. It is certain that Mr. Hooke had discovered the invention many years before Huygens mentioned it, as related in the History of the Royal Society among several other new inventions, in these words: Page 247. "There have been invented several kinds of pendulum watches for the pocket, wherein the motion is regulated by springs, etc."

Now, although this does not explicitly mention the springs being spiral or fastened to the arbor of the balance, it appears this was the case from what is related above. A passage I have seen in a letter from Sir Robert Moray to Mr. Oldenburg, dated Oxford, September 30, 1665, clears it up. It contains these words: "You [meaning Oldenburg] will be the first that knows when his [Huygens’s] watches will be ready, and I will therefore expect from you an account of them. If he imparts to you what he does, let me know it; to that purpose, you may ask him if he does not apply a spring to the arbor of the balance, and that will give him occasion to say something to you. If it be that, you may tell him what Hooke has done in that matter, and what he intends more." Although I cannot be certain what Oldenburg wrote to Monsieur Huygens, it is probable their intimacy allowed him to discover what he knew. It is evident that Huygens’s discovery of this was first published in the Journal des Sçavans and from there in the Philosophical Transactions for March 25, 1675—about ten years after that letter from Sir Robert Moray, and nearly fifteen after Hooke’s first discovery of it.

To this, I shall add what Mr. Oldenburg has printed in Philosophical Transactions, No. 118: "It is certain the describer of helioscopes [meaning Hooke] some years ago caused to be actually made some watches..."