John Harrison: Inventor of the Marine Chronometer

“No man knows who invented the mariner’s compass, or who first hollowed out a canoe from a log. 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. The forgotten inventors live for ever in the usefulness of the work they have done and the progress they have striven for.”—H. M. Hyndman.

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. He is even enabled, at some special place, to send down his grappling-irons into the sea, and pick up an electrical cable for examination and repair.

This is the result of a knowledge of Practical Astronomy. “Place an astronomer,” says Mr. Newcomb, “on board a ship; blindfold him; carry him by any route to any ocean on the globe, whether under the tropics or in one of the frigid zones; land him on the wildest rock that can be found; remove his bandage, and give him a chronometer regulated to Greenwich or Washington time, a transit instrument with the proper appliances, and the necessary books and tables, and in a single clear night he can tell his position within a hundred yards by observations of the stars. This, from a utilitarian point of view, is one of the most important operations of Practical Astronomy.”2

The Marine Chronometer was the outcome of the crying want of the sixteenth century for an instrument that should assist the navigator to find his longitude on the pathless ocean. Spain was then the principal naval power; she was the most potent monarchy in Europe, and held half America under her sway. Philip III. offered 100,000 crowns for any discovery by means of which the longitude might be determined by a better method than by the log, which was found very defective. Holland next became a great naval power, and followed the example of Spain in offering 30,000 florins for a similar discovery. But though some efforts were made, nothing practical was done, principally through the defective state of astronomical instruments. England succeeded Spain and Holland as a naval power; and when Charles II. established the Greenwich Observatory, it was made a special point that Flamsteed, the Astronomer-Royal, should direct his best energies to the perfecting of a method for finding the longitude by astronomical observations. But though Flamsteed, together with Halley and Newton, made some progress, they were prevented from obtaining ultimate success by the want of efficient chronometers and the defective nature of astronomical instruments.

Nothing was done until the reign of Queen Anne, when a petition was presented to the Legislature on the 25th of May, 1714, by “several captains of Her Majesty’s ships, merchants in London, and commanders of merchantmen, in behalf of themselves, and of all others concerned in the navigation of Great Britain,” setting forth the importance of the accurate discovery of the longitude, and the inconvenience and danger to which ships were subjected from the want of some suitable method of discovering it. The petition was referred to a committee, which took evidence on the subject. It appears that Sir Isaac Newton, with his extraordinary sagacity, hit the mark in his report. “One is,” he said, “by a watch to keep time exactly; but, by reason of the motion of a ship, and the variation of heat and cold, wet and dry, and the difference of gravity in different latitudes, such a watch hath not yet been made.”

An Act was however passed in the Session of 1714, offering a very large public reward to inventors: 10,000L. to any one who should discover a method of determining the longitude to one degree of a great circle, or 60 geographical miles; 15,000L. if it determined the same to two-thirds of that distance, or 40 geographical miles; and 20,000L. if it determined the same to one-half of the same distance, or 30 geographical miles. Commissioners were appointed by the same Act, who were instructed that “one moiety or half part of such reward shall be due and paid when the said commissioners, or the major part of them, do agree that any such method extends to the security of ships within 80 geographical miles of the shore, which are places of the greatest danger; and the other moiety or half part when a ship, by the appointment of the said commissioners, or the major part of them, shall actually sail over the ocean, from Great Britain to any such port in the West Indies as those commissioners, or the major part of them, shall choose or nominate for the experiment, without losing the longitude beyond the limits before mentioned.”

The terms of this offer indicate how great must have been the risk and inconvenience which it was desired to remedy. Indeed, it is almost inconceivable that a reward so great could be held out for a method which would merely afford security within eighty geographical miles!

This splendid reward for a method of discovering the longitude was offered to the world—to inventors and scientific men of all countries—without restriction of race, or nation, or language. As might naturally be expected, the prospect of obtaining it stimulated many ingenious men to make suggestions and contrive experiments; but for many years the successful construction of a marine time-keeper seemed almost hopeless. At length, to the surprise of every one, the prize was won by a village carpenter—a person of no school, or university, or college whatever.

Even so distinguished an artist and philosopher as Sir Christopher Wren was engaged, as late in his life as the year 1720, in attempting to solve this important problem. 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.

The truth is, that the great mechanic, like the great poet, is born, not made; and John Harrison, the winner of the famous prize, was a born mechanic. He did not, however, accomplish his object without the exercise of the greatest skill, patience, and perseverance. His efforts were long, laborious, and sometimes apparently hopeless. Indeed, his life, so far as we can ascertain the facts, affords one of the finest examples of difficulties encountered and triumphantly overcome, and of undaunted perseverance eventually crowned by success, which is to be found in the whole range of biography.

No complete narrative of Harrison’s career was ever written. Only a short notice of him appears in the ‘Biographia Britannica,’ published in 1766, during his lifetime’—the facts of which were obtained from himself. A few notices of him appear in the ‘Annual Register,’ also published during his lifetime. The final notice appeared in the volume published in 1777, the year after his death. No Life of him has since appeared. Had he been a destructive hero, and fought battles by land or sea, we should have had biographies of him without end. But he pursued a more peaceful and industrious course. His discovery conferred an incalculable advantage on navigation, and enabled innumerable lives to be saved at sea; it also added to the domains of science by its more exact measurement of time. But his memory has been suffered to pass silently away, without any record being left for the benefit and advantage of those who have succeeded him. The following memoir includes nearly all that is known of the life and labours of John Harrison.

He was born at Foulby, in the parish of Wragby, near Pontefract, Yorkshire, in March, 1693. His father, Henry Harrison, was carpenter and joiner to Sir Rowland Winn, owner of the Nostell Priory estate. The present house was built by the baronet on the site of the ancient priory. Henry Harrison was a sort of retainer of the family, and long continued in their Service.

Little is known of the boy’s education. It was certainly of a very inferior description. Like George Stephenson, Harrison always had a great difficulty in making himself understood, either by speech or writing. Indeed, every board-school boy now receives a better education than John Harrison did a hundred and eighty years ago. But education does not altogether come by reading and writing. The boy was possessed of vigorous natural abilities. He was especially attracted by every machine that moved upon wheels. The boy was ‘father to the man.’ When six years old, and lying sick of small-pox, a going watch was placed upon his pillow, which afforded him infinite delight.

When seven years old he was taken by his father to Barrow, near Barton-on-Humber, where Sir Rowland Winn had another residence and estate. Henry Harrison was still acting as the baronet’s carpenter and joiner. In course of time young Harrison joined his father in the workshop, and proved of great use to him. His opportunities for acquiring knowledge were still very few, but he applied his powers of observation and his workmanship upon the things which were nearest him. He worked in wood, and to wood he first turned his attention.

He was still fond of machines going upon wheels. He had enjoyed the sight of the big watch going upon brass wheels when he was a boy; but, now that he was a workman in wood, he proposed to make an eight-day clock, with wheels of this material. He made the clock in 1713, when he was twenty years old,4 so that he must have made diligent use of his opportunities. He had of course difficulties to encounter, and nothing can be accomplished without them; for it is difficulties that train the habits of application and perseverance. But he succeeded in making an effective clock, which counted the time with regularity. This clock is still in existence. It is to be seen at the Museum of Patents, South Kensington; and when we visited it a few months ago it was going, and still marking the moments as they passed. It is contained in a case about six feet high, with a glass front, showing a pendulum and two weights. Over the clock is the following inscription:

“This clock was made at Barrow, Lincolnshire, in the year 1715, by John Harrison, celebrated as the inventor of a nautical timepiece, or chronometer, which gained the reward of 20,000L., offered by the Board of Longitude, A.D. 1767.

“This clock strikes the hour, indicates the day of the month, and with one exception (the escapement) the wheels are entirely made of wood.”

This, however, was only a beginning. Harrison proceeded to make better clocks; and then he found it necessary to introduce metal, which was more lasting. He made pivots of brass, which moved more conveniently in sockets of wood with the use of oil. He also caused the teeth of his wheels to run against cylindrical rollers of wood, fixed by brass pins, at a proper distance from the axis of the pinions; and thus to a considerable extent removed the inconveniences of friction.

In the meantime Harrison eagerly improved every incident from which he might derive further information. There was a clergyman who came every Sunday to the village to officiate in the neighbourhood; and having heard of the sedulous application of the young carpenter, he lent him a manuscript copy of Professor Saunderson’s discourses. That blind professor had prepared several lectures on natural philosophy for the use of his students, though they were not intended for publication. Young Harrison now proceeded to copy them out, together with the diagrams. Sometimes, indeed, he spent the greater part of the night in writing or drawing.

As part of his business, he undertook to survey land, and to repair clocks and watches, besides carrying on his trade of a carpenter. He soon obtained a considerable knowledge of what had been done in clocks and watches, and was able to do not only what the best professional workers had done, but to strike out entirely new lights in the clock and watch-making business. He found out a method of diminishing friction by adding a joint to the pallets of the pendulum, whereby they were made to work in the nature of rollers of a large radius, without any sliding, as usual, upon the teeth of the wheel. He constructed a clock on the recoiling principle, which went perfectly, and never lost a minute within fourteen years. Sir Edmund Denison Beckett says that he invented this method in order to save himself the trouble of going so frequently to oil the escapement of a turret clock, of which he had charge; though there were other influences at work besides this.

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. Graham, the well-known clock-maker, invented the mercurial compensation pendulum, consisting of a glass or iron jar filled with quicksilver and fixed to the end of the pendulum rod. When the rod was lengthened by heat, the quicksilver and the jar which contained it were simultaneously expanded and elevated, and the centre of oscillation was thus continued at the same distance from the point of suspension.

But the difficulty, to a certain extent, remained unconquered until Harrison took the matter in hand. 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. By this means the pendulum contained the power of equalising its own action, and the centre of oscillation continued at the same absolute distance from the point of suspension through all the variations of heat and cold during the year.5

Thus by the year 1726, when he was only thirty-three years old, Harrison had furnished himself with two compensation clocks, in which all the irregularities to which these machines were subject, were either removed or so happily balanced, one metal against the other, that the two clocks kept time together in different parts of his house, without the variation of more than a single second in the month. One of them, indeed, which he kept by him for his own use, and constantly compared with a fixed star, did not vary so much as one whole minute during the ten years that he continued in the country after finishing the machine.6

Living, as he did, not far from the sea, Harrison next endeavoured to arrange his timekeeper for purposes of navigation.

He tried his clock in a vessel belonging to Barton-on-Humber; but his compensating pendulum could there be of comparatively little use; for it was liable to be tossed hither or thither by the sudden motions of the ship. He found it necessary, therefore, to mount a chronometer, or portable timekeeper, which might be taken from place to place, and subjected to the violent and irregular motion of a ship at sea, without affecting its rate of going. It was evident to him that the first mover must be changed from a weight and pendulum to a spring wound up and a compensating balance.

He now applied his genius in this direction. After pondering over the subject, he proceeded to London in 1728, and exhibited his drawings to Dr. Halley, then Astronomer-Royal. The Doctor referred him to Mr. George Graham, the distinguished horologer, inventor of the dead-beat escapement and the mercurial pendulum. After examining the drawings and holding some converse with Harrison, Graham perceived him to be a man of uncommon merit, and gave him every encouragement. He recommended him, however, to make his machine before again applying to the Board of Longitude.

Harrison returned home to Barrow to complete his task, and many years elapsed before he again appeared in London to present his first chronometer.

The remarkable success which Harrison had achieved in his compensating pendulum could not but urge him on to further experiments. He was no doubt to a certain extent influenced by the reward of 20,000L. which the English Government had offered for an instrument that should enable the longitude to be more accurately determined by navigators at sea than was then possible; and it was with the object of obtaining pecuniary assistance to assist him in completing his chronometer that Harrison had, in 1728, made his first visit to London to exhibit his drawings.

The Act of Parliament offering this superb reward was passed in 1714, fourteen years before, but no attempt had been made to claim it. It was right that England, then rapidly advancing to the first position as a commercial nation, should make every effort to render navigation less hazardous. Before correct chronometers were invented, or good lunar tables were prepared,7 the ship, when fairly at sea, out of sight of land, and battling with the winds and tides, was in a measure lost. No method existed for accurately ascertaining the longitude. The ship might be out of its course for one or two hundred miles, for anything that the navigator knew; and only the wreck of his ship on some unknown coast told of the mistake that he had made in his reckoning.

It may here be mentioned that it was comparatively easy to determine the latitude of a ship at sea every day when the sun was visible. The latitude—that is, the distance of any spot from the equator and the pole—might be found by a simple observation with the sextant. The altitude of the sun at noon is found, and by a short calculation the position of the ship can be ascertained.

The sextant, which is the instrument universally used at sea, was gradually evolved from similar instruments used from the earliest times. The object of this instrument has always been to find the angular distance between two bodies—that is to say, the angle contained by two straight lines, drawn from those bodies to meet in the observer’s eye. The simplest instrument of this kind may be well represented by a pair of compasses. If the hinge is held to the eye, one leg pointed to the distant horizon, and the other leg pointed to the sun, the position of the two legs will show the angular distance of the sun from the horizon at the moment of observation.

Until the end of the seventeenth century, the instrument used was of this simple kind. It was generally a large quadrant, with one or two bars moving on a hinge,—to all intents and purposes a huge pair of compasses. The direction of the sight was fixed by the use of a slit and a pointer, much as in the ordinary rifle. This instrument was vastly improved by the use of a telescope, which not only allowed fainter objects to be seen, but especially enabled the sight to be accurately directed to the object observed.

The instruments of the pre-telescopic age reached their glory in the hands of Tycho Brahe. He used magnificent instruments of the simple “pair of compasses” kind—circles, quadrants, and sextants. 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; to Robert Hooke, who, in 1660, proposed to apply it to the quadrant; to Sir Isaac Newton, who designed a reflecting quadrant;8 and to John Hadley, who introduced it. 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. 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. But if, in any locality, we know the local time, and also the local time of some other locality at that moment—say, of the Observatory at Greenwich we can, by comparing the two local times, determine the difference of local times, or, what is the same thing, the difference of longitude between the two places. It was necessary therefore for the navigator to be in possession of a first-rate watch or chronometer, to enable him to determine accurately the position of his ship at sea, as respected the longitude.

Before the middle of the eighteenth century good watches were comparatively unknown. The navigator mainly relied, for his approximate longitude, upon his Dead Reckoning, without any observation of the heavenly bodies. He depended upon the accuracy of the course which he had steered by the compass, and the mensuration of the ship’s velocity by an instrument called the Log, as well as by combining and rectifying all the allowances for drift, lee-way, and so on, according to the trim of the ship; but all of these were liable to much uncertainty, especially when the sea was in a boisterous condition. There was another and independent course which might have been adopted—that is, by observation of the moon, which is constantly moving amongst the stars from west to east. But until the middle of the eighteenth century good lunar tables were as much unknown as good watches.

Hence a method of ascertaining the longitude, with the same degree of accuracy which is attainable in respect of latitude, had for ages been the grand desideratum for men “who go down to the sea in ships.” Mr. Macpherson, in his important work entitled ‘The Annals of Commerce,’ observes, “Since the year 1714, when Parliament offered a reward of 20,000L. for the best method of ascertaining the longitude at sea, many schemes have been devised, but all to little or no purpose, as going generally upon wrong principles, till that heaven-taught artist Mr. John Harrison arose;” and by him, as Mr. Macpherson goes on to say, the difficulty was conquered, having devoted to it “the assiduous studies of a long life.”