The invention of spring or pocket watches belongs to the 17th century. It is true, we find mention made of a watch presented to Charles V. in the history of that prince: but this, in all probability, was no more than a kind of clock to be set on a table, some resemblance whereof we have still remaining in the ancient pieces made before the year 1670. There was also a story of a watch having been discovered in Scotland, belonging to Kins: Robert Bruce; but this we believe has turned out altogether erroneous. The glory of this very useful invention lies between Dr. Hooke and M. Huygens; but to which of them it properly belongs, has been greatly disputed; the English ascribing it to the former, and the French, Dutch, etc.c. to the latter. Mr. Der-ham, in his Artificial Clockmaker, says, roundly, that Dr. Hooke was the inventor; and adds, that he contrived various ways of regulation. One way was, with a loadstone; another with a tender straight spring, one end whereof played backwards and forwards with the balance, so that the balance was to the spring as the bob to a pendulum, and the spring as the rod thereof. A third method was, with two balances, of which there were divers sorts; some having a spiral spring to the balance for a regulator, and others not. But the way that prevailed, and which still continues to prevail, was, with one balance, and one spring running round the upper part of the verge; though this has a disadvantage, from which those with two springs, etc. were free, since a sudden jerk, or confused shake, will alter its vibrations, and disturb its motion.

The time of these inventions was about the year 1658; as appears, among other evidences, from an inscription on one of the double-balance watches presented to King Charles II. viz. "Rob. Hooke invert. 1658. T. Tompion fecit, 1675." The invention presently got into reputation, both at home and abroad: and two of them were sent for by the dauphin of France, Soon after this, M. Huygens' watch with a spiral spring got abroad, and made a great noise in England, as if the longitude could be found by it. It is certain, however, that his invention was later than the year 1673, when his cook "De floral. Qscillat" was published; wherein he has not one word of this, though he has of several other contri-vances in the same way.

One of these the Lord Brouncker sent for out of France, where M. Huygens had got a patent for them. This watch agreed with Dr. Hooke's, in the application of the spring to the balance; only M. Huygens' had a long spiral springs and the pulses and beats were much slower. The balance, instead of turning quite round, as Dr Hooke's, turns several rounds every vibration.

Mr. Derham suggests, that he has reason to think M. Huy-gens' fancy was first set to work by some intelligence he might have of Dr. Hooke's invention from Mr. Oldensworth, or some other of his correspondents in England; and this, notwithstanding Mr. Oldensworth's attempt to vindicate himself in the Philosophical Transactions, appears to be the truth. Huygens invented divers other kinds of watches, some of them without any string- or chain at all; which he called particularly, pendulum watches.