HARRISON, JOHN, was born at Faulby, near Pontefract, in York shire, in the year 1693. Ile was the son of a carpenter, which profession he also followed during several years. In 1700 the family removed to Barrow, in Lincolnshire. Harrison early displayed an attachment to mechanical pursuits, and his attention was particularly directed to the improvement of clocks. After many failures and many minor improvements, he at length succeeded in constructing a pendulum, the excellence of which depended on the differeut degrees in which metals are expanded or contracted by variations of temperature. This important principle is now employed in the construction of the balance-wheels of chronometers, and is that on which the accuracy of those timekeepers mainly depends.
In the year 1714 an act was passed offering a reward of 10,0001., 15,000/., and 20,000/, respectively, for a method of ascertaining the longitude within 60, 40, or 30 miles. In 1735 Harrison came up to London with a timepiece which he bad constructed. Having obtained certificates of its excellence from Ifalley, Graham, and others, he was allowed, in 1736, to proceed with it to Lisbon in a king's ship, and was enabled to correct the reckoning a degree and a half. Ou this the commissioners under the act gave him 5001. to enable him to proceed with his improvements. After constructing two other time pieces, he at last made a tbird, which he considered sufficiently correct to entitle him to claim a trial of it, and the commissioners accordingly, in 1761, sent out his son William in a kiog's ship to Jamaica. On his &rival at Port Royal, the watch was found to be wrong only seconds ; and on his return to Portsmouth, in 1762, only 1 minute 54i seconds. This was sufficient to determine the longitude within
18 miles, and Harrison accordingly claimed the reward. After another voyage to Jamaica and some further trials, an act was passed, in 1765, which awarded the 20,0001. to Harrison, one-half to be paid on his explaining the principle of construction of his time-piece, the other half as soon as it was ascertained that the instrument oould be made by others. After some delays and disputes, llarrison, in 1767, received the whole sum of 20,0001.
Next to the principle of the different expansibility of metals, which is applicable both to tho pendulums of clocks and the balanee-sheels of watches, the most important of the many inventions and improve mouth which in the course of fifty years he introduced, is perhaps that of the going fusee, by which a watch can be wound up without interrupting its movement.
He died at his house in Red Lion Square in 1776, in his eighty third year. His phraseology is said to have been uncouth. On mechanics and subjects connected with that science he could converse with considerable clearness; but ho found great difficulty in express ing his sentiments in writing, as is evident in his 'Description con cerning suoh Mechanism as will afford a nice or true Mensuration of Time.' In the last volume of the Biographia Britannica, published in 1706, there is a memoir of Harrison drawn up from materiels furnished by himself. See also Mutton's Mathunat. Did. and the Gallery of Portraits, mul. v., p. 153.