Samuel Smiles

“ One of the most extraordinary things connected with Applied Science is the method by which the Navigator is enabled to find the exact spot of sea on which his ship rides. There may be nothing but water and sky within his view; he may be in the midst of the ocean, or gradually nearing the land; the curvature of the globe baffles the search of his telescope; but if he have a correct chronometer, and can make an astronomical observation, he may readily ascertain his longitude, and know his approximate position — how far he is from home, as well as from his intended destination. ”

“ I do, in their name congratulate you upon the successes you have already had, and I most sincerely wish that all your future trials may in every way prove answerable to these beginnings, and that the full accomplishment of your great undertaking may at last be crowned with all the reputation and advantage to yourself that your warmest wishes may suggest, and to which so many years so laudably and so diligently spent in the improvement of those talents which God Almighty has bestowed upon you, will so justly entitle your constant and unwearied perseverance. ”

“ Every one knows the beautiful machinery of a timepiece, and the perfect tools required to produce such a machine. Some of these tools Harrison procured in London, but the greater number he provided for himself; and many entirely new adaptations were required for his chronometer. As wood could no longer be exclusively employed, as in his first clock, he had to teach himself to work accurately and minutely in brass and other metals. ”

“ The question of longitude is purely a question of TIME. The circuit of the globe, east and west, is simply represented by twenty-four hours. Each place has its own time. It is very easy to determine the local time at any spot by observations made at that spot. But, as time is always changing, the knowledge of the local time gives no idea of the actual position; and still less of a moving object — say, of a ship at sea. ”

“ The power to observe accurately the sun, moon, and planets, so as to fix a vessel's actual position when far out of sight of land, enabling long voyages to be safely made; the marvellous improvements in ship-building, which shortened passages by sailing vessels, and vastly reduced freights even before steam gave an independent force to the carrier — each and all were done by small advances, which together contributed to the general movement of mankind.... Each owes all to the others. ”

“ Harrison's experience with the compensation pendulum of his clock now proved of service to him. He had proceeded to introduce a similar expedient in his proposed chronometer. As is well known to those who are acquainted with the nature of springs moved by balances, the stronger those springs are, the quicker the vibrations of the balances are performed, and vice versa; hence it follows that those springs, when braced by cold, or when relaxed by heat, must of necessity cause the timekeeper to go either faster or slower, unless some method could be found to remedy the inconvenience. ”

“ But his most important invention, at this early period of his life, was his compensation pendulum. Every one knows that metals expand with heat and contract by cold. The pendulum of the clock therefore expanded in summer and contracted in winter, thereby interfering with the regular going of the clock. Huygens had by his cylindrical checks removed the great irregularity arising from the unequal lengths of the oscillations; but the pendulum was affected by the tossing of a ship at sea, and was also subject to a variation in weight, depending on the parallel of latitude. ”

“ The modern sextant is merely a modification of Newton's or Badley's quadrant, and its present construction seems to be perfect.
It therefore became possible accurately to determine the position of a ship at sea as regarded its latitude. But it was quite different as regarded the longitude — that is, the distance of any place from a given meridian, eastward or westward. In the case of longitude there is no fixed spot to which reference can be made. The rotation of the earth makes the existence of such a spot impossible. ”

“ Indeed, it is amazing to think of the number of clever, skilful, and industrious men who have been engaged for many hundred years in the production of that exquisite fabric — so useful to everybody, whether scientific or otherwise, on land or sea the modern watch.
It is unnecessary here to mention in detail the particulars of Harrison's invention. These were published by himself in his 'Principles of Mr. Harrison's Timekeeper.' It may, however, be mentioned that he invented a method by which the chronometer might be kept going without losing any portion of time. ”

“ As has been observed, in the memoir of him contained in the 'Biographia Britannica,' [3] "This noble invention, like some others of the most useful ones to human life, seems to be reserved for the peculiar glory of an ordinary mechanic, who, by indefatigable industry, under the guidance of no ordinary sagacity, hath seemingly at last surmounted all difficulties, and brought it to a most unexpected degree of perfection." Where learning and science failed, natural genius seems to have triumphed. ”

“ But perhaps the most interesting works connected with John Harrison and the great labour of his life, are the wooden clock at the South Kensington Museum, and the four chronometers made by him for the Government, which are still preserved at the Royal Observatory, Greenwich. The three early ones are of great weight, and can scarcely be moved without some bodily labour. But the fourth, the marine chronometer or watch, is of small dimensions, and is easily handled. It still possesses the power of going accurately ”

“ Captain Proctor answered the First Lord from Spithead, dated May l7th, 1736, promising his attention to Harrison's comfort, but intimating his fear that he had attempted impossibilities. It is always so with a new thing. The first steam-engine, the first gaslight, the first locomotive, the first steamboat to America, the first electric telegraph, were all impossibilities!
This first chronometer behaved very well on the outward voyage in the Centurion. It was not affected by the roughest weather, or by the working of the ship through the rolling waves of the Bay of Biscay. ”

“ He observed that all rods of metal do not alter their lengths equally by heat, or, on the contrary, become shorter by cold, but some more sensibly than others. After innumerable experiments Harrison at length composed a frame somewhat resembling a gridiron, in which the alternate bars were of steel and of brass, and so arranged that those which expanded the most were counteracted by those which expanded the least. ”

“ He found the principles which he had adopted in his larger machines applied equally well in the smaller, and the performances of the last surpassed his utmost expectations. But in the meantime, as his third timekeeper was, in his opinion, sufficient to supply the requirements of the Board of Longitude as respected the highest reward offered, he applied to the Commissioners for leave to try that instrument on board a royal ship to some port in the West Indies, as directed by the statute of Queen Anne. ”

“ These were for the most part ponderous fixed instruments of little or no use for the purposes of navigation. But Tycho Brahe's sextant proved the forerunner of the modern instrument. The general structure is the same; but the vast improvement of the modern sextant is due, firstly, to the use of the reflecting mirror, and, secondly, to the use of the telescope for accurate sighting. These improvements were due to many scientific men — to William Gascoigne, who first used the telescope, about 1640 ”

“ In these expeditions, the officers, the sailors, and the scientific men, were constantly brought face to face with unforeseen difficulties and dangers, which brought forth their highest qualities as men. ”

“ The method adopted by Harrison was his compensation balance, doubtless the backbone of his invention. His "thermometer kirb," he himself says, "is composed of two thin plates of brass and steel, riveted together in several places, which, by the greater expansion of brass than steel by heat and contraction by cold, becomes convex on the brass side in hot weather and convex on the steel side in cold weather ”