John Harrison

John Harrison was born on March 24, 1693 in Foulby, a small village near Wakefield in the West Riding of Yorkshire, the first of five children of Henry Harrison, a carpenter and joiner ^[1]. Around 1700 the family moved to Barrow upon Humber in north Lincolnshire, where Henry worked on the local estate and John grew up learning woodworking at his father's bench ^[2].

Harrison had almost no formal schooling. A story preserved in early accounts holds that during a childhood bout of smallpox he was given a watch to occupy him, and that he spent hours studying its motion ^[1]. Whatever the truth of the tale, his curiosity about mechanics was real and persistent. A visiting clergyman is said to have lent him a manuscript copy of lectures on natural philosophy by the Cambridge mathematician Nicholas Saunderson, which the young man copied out word for word, diagrams included ^[2].

By his late teens Harrison was repairing and then building clocks, applying a joiner's knowledge of timber to a trade normally worked in brass and steel. His earliest surviving longcase clock, completed in 1713 before his twentieth birthday, has a movement made almost entirely of wood, with oak wheels and boxwood teeth ^[3]. Two further wooden clocks from 1715 and 1717 survive, and the 1717 example now belongs to the Worshipful Company of Clockmakers ^[3].

During the 1720s Harrison, often working with his younger brother James, produced clocks of startling originality for a village tradesman. A turret clock he built around 1722 for the stable block at Brocklesby Park ran without lubrication, using wooden bearings and the self-oiling tropical hardwood lignum vitae, and it is still running today ^[3]. In the same period he devised two inventions that became standard equipment in precision clocks: the gridiron pendulum, which used alternating brass and steel rods so that thermal expansion in one metal cancelled the other, and the grasshopper escapement, a nearly frictionless mechanism for transferring power to the pendulum ^[4].

The problem that would consume his life had been given a price in 1714, when Parliament passed the Longitude Act. Sailors could fix latitude from the sun and stars, but longitude required knowing the time at a reference point, and no clock could keep time on a pitching, rolling, damp ship. The Act offered rewards up to 20,000 pounds, a fortune, for a practical method accurate to within half a degree on a voyage to the West Indies ^[5].

Harrison decided a sea clock was possible. In 1730 he travelled to London with drawings and called on Edmond Halley, the Astronomer Royal, who sent him to the eminent watchmaker George Graham. Graham was impressed enough to lend Harrison money without interest or security, a remarkable act of confidence in an unknown provincial ^[1]. Harrison returned home and spent five years building his first marine timekeeper, now called H1, a heavy brass machine with linked balances designed to counteract a ship's motion ^[4].

H1 was trialled on a voyage to Lisbon and back in 1736 aboard HMS Centurion and HMS Orford. On the return leg Harrison used his machine to correct the ship's estimated position by about sixty miles, and the master certified the result ^[5]. The Board of Longitude, meeting for the first time in response to his work, granted him 500 pounds to continue. His second machine, H2, was finished by 1739 but never went to sea, partly because Harrison had already spotted a flaw in its balances. He then laboured for nearly two decades on H3, an intricate clock of over 700 parts that introduced the bimetallic strip and the caged roller bearing, two devices still in use in engineering today ^[4].

The breakthrough came from an unexpected direction. In the 1750s Harrison concluded that a large watch, not a large clock, could do the job, provided its balance oscillated fast and with high energy. The result was H4, completed in 1759: a silver-cased watch about thirteen centimetres across, with a jewelled movement, a temperature-compensated balance, and a refined verge escapement ^[3]. It remains among the most celebrated single objects in the history of technology.

On the official trial, a voyage to Jamaica aboard HMS Deptford beginning in November 1761, H4 was found to be in error by only about five seconds after eighty-one days at sea, a performance comfortably inside the limit for the full reward ^[5]. A second trial to Barbados in 1764 confirmed the watch's ability, with the error over the outward voyage computed at well under the half-degree standard ^[2]. Among John Harrison achievements, H4 stands first: it demonstrated that longitude could be carried in a seaman's cabin, and copies of it, notably Larcum Kendall's K1, accompanied James Cook on his second and third Pacific voyages, where Cook praised the watch's reliability ^[6].

Winning the trials did not mean winning the money. The Board of Longitude, which included astronomers who favoured the rival lunar distance method, ruled that H4's success might have been luck and demanded further proof ^[5]. Nevil Maskelyne, appointed Astronomer Royal in 1765, was both a judge of Harrison's claim and a champion of the astronomical alternative, a conflict that Harrison and his son William resented bitterly ^[2].

In 1765 Parliament awarded Harrison 10,000 pounds, half the great reward, but only after he disclosed the watch's construction to a panel of experts and surrendered H4 itself. The remaining half was made conditional on his producing further timekeepers to prove the design could be replicated ^[5]. Harrison, by now in his seventies, considered the terms punitive. He built one more watch, H5, and in 1772 his son secured the interest of King George III, who tested H5 privately at his observatory at Kew and found it performed superbly. The king is reported to have taken Harrison's side in the dispute ^[1].

With royal backing, Harrison petitioned Parliament directly. In June 1773 he was granted a further 8,750 pounds by Act of Parliament, in recognition of his life's work, though the Board never formally declared him winner of the longitude prize ^[5]. Counting earlier grants, he received more than 23,000 pounds from public funds over his career, one of the largest sums ever paid to an inventor in the eighteenth century ^[2].

Harrison married twice. His first wife, Elizabeth Barrel, whom he wed in 1718, died in 1726, leaving a son, John. The following year he married Elizabeth Scott, with whom he had two more children, William and Elizabeth ^[2]. William Harrison became his father's indispensable partner, sailing with the timekeepers on their trials to Jamaica and Barbados and pressing the family's case before the Board and Parliament ^[5].

Contemporaries described Harrison as stubborn, plain-spoken, and almost impossible to follow in print; his late pamphlets are notoriously tangled, a reflection of a mind trained at the workbench rather than the writing desk ^[1]. He was also a serious musician. He served as choirmaster at Barrow parish church, experimented with bell tuning, and published his own system of musical temperament based on the mathematical constant pi, a scheme he defended as vigorously as his clocks ^[2].

From about 1737 Harrison lived and worked in London, settling for many years in Red Lion Square in Holborn, where he kept his workshop through the long decades of the H3 and H4 projects ^[3].

Harrison spent his final years in Red Lion Square and died there on March 24, 1776, the day of his eighty-third birthday ^[1]. He was buried in the churchyard of St John's, Hampstead, where his tomb, later restored by the Worshipful Company of Clockmakers, still stands ^[3]. A memorial tablet to him was placed in Westminster Abbey in 2006, close to the graves of other figures of British science ^[6].

His technical legacy spread quickly. Once H4 proved the concept, watchmakers such as John Arnold and Thomas Earnshaw simplified the marine chronometer into an instrument that could be produced in quantity, and by the early nineteenth century chronometers were routine equipment on naval and merchant ships ^[4]. The gridiron pendulum, the bimetallic strip, and the caged roller bearing all passed into general engineering use, and his lubrication-free wooden clocks still fascinate horologists as feats of material insight ^[3].

Public interest in the story revived sharply after 1995, when Dava Sobel's bestselling book Longitude retold the contest between Harrison and the astronomers, followed by a television adaptation in 2000 ^[6]. His first three sea clocks, restored to working order in the twentieth century by the horologist Rupert Gould, are displayed at the Royal Observatory in Greenwich alongside H4, where they remain among the most visited objects in the museum ^[3]. For readers of any John Harrison biography, the essential John Harrison facts endure: a village carpenter's son, without schooling or patronage, built the machines that let sailors know where they were.