Marine Chronometer by Thomas Earnshaw
c. 1800 · Brass movement
British Museum, London
Thomas Earnshaw
British · 1749-1829
Thomas Earnshaw, oil on canvas by Martin Archer Shee, circa 1808. A half-length seated portrait, right hand resting on a table beside a standard Earnshaw-type chronometer, painted within Earnshaw's own lifetime. Held by the National Maritime Museum, Greenwich since its acquisition through the Caird Fund.
National Maritime Museum, Greenwich, London. Caird Fund| Worked as | Chronometer maker, Watchmaker |
|---|---|
| Born | 4 February 1749 · Ashton-under-Lyne, Lancashire, England |
| Died | 1 March 1829 · Chenies Street, Bedford Square, London. |
| Nationality | British |
| In this archive | 1 artwork |
| Sources | 23 cited |
| Last verified |
About this page 1 artwork in the archive · Last verified · 23 sources cited
On this page 14 sections
ContentsClose
Thomas Earnshaw did not invent the marine chronometer. John Harrison had already proved, decades before Earnshaw's own workshop existed, that a portable timekeeper could cross an ocean and still tell a captain where he was. What Earnshaw did was narrower and, in its consequences, larger: he worked out how to build that same order of accuracy into an instrument simple and cheap enough to make in quantity, and to make by dividing the labour rather than by one master's hand alone. A Kendall copy of Harrison's own design had cost the Admiralty 450 pounds. An Earnshaw box chronometer of the 1780s cost as little as 65. That gap in price, not a single invention, is why a ship like HMS Beagle could carry twenty-two chronometers in 1831 where a generation earlier a captain counted himself lucky to have one.
The standard account stops there, at the workshop's success, and skips the man who nearly did not have one. Earnshaw married before he had finished his apprenticeship, had three sons within four years, and by 1774 was facing debtors' prison. He fled to Ireland, then turned back and surrendered himself to the Fleet. He did not clear his debts and open the business that made his name until 1780, at 119 High Holborn. The same man who is credited by the Dictionary of National Biography with making precision timekeeping cheap enough for ordinary buyers spent the years just before that achievement running from his own creditors.
The single hardest thing to find on this maker is not a date or a workshop address. It is that Earnshaw's own most-discussed rival, John Arnold, had been dead for six years by the time the Board of Longitude finally split its 1805 award between Earnshaw and a man named only as "John Arnold" in the fullest surviving account of the payment - a discrepancy this record states plainly rather than smooths away, because it changes who actually collected the money Earnshaw spent the rest of his life insisting was rightfully his alone.
Records in this archive
Images
Chronology
- 1749-02-04
- c. 1763
Apprenticed to a watchmaker at about fourteen years old, per the Dictionary of National Biography.2
- 1774
Facing debtors' prison, having married before completing his apprenticeship and fathered three sons within four years; fled to Ireland, then returned and surrendered to the Fleet Prison in December, per the British Museum's own curatorial account.3
- by 1780
Debts cleared and a successful business established, allowing him to work on improvements to the pivoted detent escapement.3
- early 1780s
Devises his own form of the spring detent escapement and a split-bimetallic temperature-compensation balance.13
- 1782-05
John Arnold is granted a patent covering his own version of a spring detent escapement.13
- 1783-02
Earnshaw's escapement receives patent protection, registered in the name of Thomas Wright, watchmaker to the King, on Earnshaw's behalf, in exchange for a 100-guinea fee and a profit share.131415
- 1791-07
Captain William Bligh buys Earnshaw chronometer no. 1503 for 40 guineas, ahead of the second breadfruit voyage aboard HMS Providence.1
- 1791
Earnshaw begins submitting timekeepers to the Board of Longitude.2
- 1793
Competes again before the Board of Longitude, backed by the Astronomer Royal, Nevil Maskelyne.2
- 1794
Installs the completed regulator at Armagh Observatory; purchase price 100 pounds, plus a further 100 pounds for his own travel and installation.21
- c. 1795-1805
The marine chronometer later numbered 509, now the subject of a separate record in this archive, is made at 119 High Holborn.3
- 1796
Chronometer no. 265 outperforms a rival instrument by Josiah Emery in trial, but the Board's rating method, measured against the first month's own performance rather than an absolute standard, denies Earnshaw recognition for it.1
- 1801-1803
Matthew Flinders carries Earnshaw timekeepers E520 and E543, at 100 guineas each, on HMS Investigator's survey and circumnavigation of Australia.120
- 1805
The Board of Longitude's award to Earnshaw is finally settled after prolonged argument. Two sources give 3,000 pounds to Earnshaw; a third gives 2,500 pounds to Earnshaw and 1,672 pounds to John Roger Arnold, son of the already-deceased John Arnold. The sources do not agree, and this record does not resolve the figure.1221
- 1806
Publishes "Explanations of Timekeepers constructed by the Author and the late Mr. John Arnold".2
- 1808
Publishes "Longitude: an Appeal to the Public, stating T. E.'s Claim to the Original Invention of the Improvements in his Timekeepers", naming the Larkins of Blackheath regulator as the best clock he ever made.2419
- 1821
Chronometer no. 512, East India Company property, is issued to the Company ship Thomas Grenville and performs badly.6
- 1823
On inspection of chronometer no. 512, Earnshaw states that it "cannot be depended upon"; the East India Company records its displeasure and adopts a new reporting rule for all its ships' chronometers.6
- 1829-03-01
Dies at Chenies Street, Bedford Square, London, aged eighty. Buried at St Giles-in-the-Fields, Bloomsbury.222
- 1831-12 to 1836-11
Chronometer no. 509 serves aboard HMS Beagle's second survey voyage under Captain Robert FitzRoy, with Charles Darwin aboard; covered in detail in this archive's separate record on the object.3
- 1929
A brass memorial plaque to Earnshaw is placed at St Giles-in-the-Fields by the Worshipful Company of Clockmakers and the British Horological Institute; the exact date is given as 1929 in this record's own source list but could not be independently confirmed against the source cited.22
- 1936-07
Chronometer no. 512 is bought by Sir James Caird from the London dealers Clowes and Jauncey for 16 pounds, its history untraceable between 1823 and this purchase.6
- 1937
Chronometer E520, carried on Flinders' Investigator voyage, is bought by the Sydney Technical Museum from a private collector; its connection to the voyage is not identified until 1976.20
- 1958
The British Museum acquires chronometer no. 509 with the rest of the Ilbert Collection.3
- 1989
The British Museum purchases the Catherwood-signed, Earnshaw-attributed longcase regulator from the dealer Philip Whyte.4
- 1998-1999
The National Maritime Museum, Greenwich stages the exhibition "Arnold & Earnshaw, Pioneers of the Chronometer", pairing the two rivals' work.4
- 2011-11-22
A surviving copy of Earnshaw's 1808 pamphlet sells at Bonhams, London, for 1,062.50 pounds including premium.19
- 2012
A modern watch brand trading as Thomas Earnshaw is founded, unconnected to the historical workshop, explicitly invoking his name and reputation.23
The market
Prices for signed Earnshaw pieces span a wide range. At the lower end of the trade, a silver-cased Earnshaw key-wind chronometer pocket watch made 2,805 pounds including premium at Bonhams in February 2023, and a lot pairing an Earnshaw movement with an unrelated Dutton movement made 2,250 pounds including premium in 2013. At the higher end, a fine gold pair-cased Earnshaw pocket chronometer from the Knowles-Brown Collection carried a Sotheby's estimate of 20,000 to 30,000 pounds in 2017, though the price it actually realized is not published in the sources consulted for this record.
Bonhams' own published results give one inclusive "sold for" figure rather than separating hammer price from buyer's premium, and this record states that plainly rather than assigning either figure to the wrong column on a guess. Documented voyage history moves value far more than signature alone: this archive's own record on chronometer no. 509 already shows a comparable Beagle-associated instrument, by a different maker, selling well into six figures once its history was established, a scale no signed Earnshaw watch examined for this record reaches on its maker's name by itself. A genuine literature item, Earnshaw's own 1808 pamphlet stating his case against Arnold, sold at Bonhams in 2011 for 1,062.50 pounds including premium, a small but real data point on how the market still prices the argument itself, not only the instruments it was fought over.
Recorded without a public price
- 22 February 2023 · Silver key-wind open-face chronometer pocket watch, no. 3346/757, circa 1810 and later · Bonhams · not published separately Bonhams' own results page gives a single inclusive figure, "sold for GBP 2,805 inc. premium", rather than a separate hammer price.
- 11 June 2013 · Chronometer movement no. 534, lotted together with an unrelated cylinder movement by William Dutton and Sons · Bonhams · not published separately Sold for GBP 2,250 inc. premium, one inclusive figure per Bonhams' own listing; price covers both movements in the lot, not the Earnshaw movement alone.
- 22 November 2011 · Earnshaw's own 1808 pamphlet, "Longitude. An Appeal to the Public...", first edition, F. Wingrave · Bonhams · not published separately A literature item, not an instrument. Sold for GBP 1,062.50 inc. premium per Bonhams' own listing.
- 2017 · Gold pair-cased pocket chronometer, London, 1801, no. 626/3069, from the Knowles-Brown Collection · Sotheby's · not published in the source consulted Estimate GBP 20,000-30,000 in Sotheby's own "George Daniels: 20th Century Innovator" sale catalogue; the price actually realized is not published in the source consulted for this record, and this record does not estimate one.
Where to see the work
| Institution | City | Holdings | Note |
|---|---|---|---|
| British Museum | London | Marine chronometer no. 509 (the HMS Beagle chronometer, subject of a separate record in this archive) and a longcase astronomical regulator signed Catherwood but attributed to Earnshaw's own workshop. | Both on public display, Room 39, Clocks and watches. |
| Worshipful Company of Clockmakers' Museum | London | A marine chronometer of about 1800. | The Company's historic collection, now housed within the Science Museum. |
| National Maritime Museum, Royal Museums Greenwich | London | The 1808 Martin Archer Shee portrait of Earnshaw; chronometer no. 512, documenting an East India Company service failure; a model of Earnshaw's escapement. | The portrait used on this page is held here. |
| Science Museum Group | London | A gold-cased chronometer watch, no. 498, hallmarked 1807-08, and a gold-cased chronometer watch no. 728, among other Earnshaw pieces. | Collection images are licensed CC BY-NC-SA and are not reproduced in this record on that basis; described here from the Museum's own published catalogue text only. |
| Smithsonian, National Museum of American History | Washington, D.C. | A Thomas Earnshaw box chronometer. | |
| Powerhouse Museum | Sydney, Australia | Chronometer E520, carried on Matthew Flinders' Investigator voyage, 1801-1803. | Acquired 1937; its voyage history was not confirmed until 1976. |
| Armagh Observatory and Planetarium | Armagh, Northern Ireland | Two astronomical regulator clocks built by Earnshaw for the Observatory, installed 1794 and afterward. | Commissioned personally by Nevil Maskelyne. |
Forgeries and misattributions
- A pocket chronometer movement of about 1783, carrying the Wright's patent punchmark, rehoused in plain silver inner and outer cases hallmarked London 1805.
- Sold by Sotheby's in its 2004 Time Museum sale as a catalogued, honestly described example of an authentic Earnshaw movement in later casework, twenty-two years newer than the movement itself. The punchmark, from the arrangement under which Thomas Wright held Earnshaw's first patent, was normally removed from Earnshaw's later work once his debt to Wright was repaid, which the cataloguer states makes its survival on this particular movement unique among known examples. Identified and catalogued by Sotheby's own specialist department at the point of sale, from the mismatch between the movement's early features and punchmark and the case's later hallmark date, rather than exposed after the fact as a deception.14
The essay
Chapter 1The instrument he did not invent, and the industry he did
By the late eighteenth century the theory of the sea clock was settled.
By the late eighteenth century the theory of the sea clock was settled. John Harrison had shown, across four increasingly refined machines built between the 1730s and the 1760s, that a timekeeper could hold Greenwich time accurately enough across a long voyage for a navigator to derive longitude from the difference between local noon and the clock's reading. What Harrison had not shown was how to make a second one. His solution was a bespoke masterpiece, and Larcum Kendall's own careful copy of it, K1, cost the Admiralty 450 pounds to build.
Earnshaw's achievement was to make the same order of accuracy reproducible. By the 1780s a new, boxed Earnshaw chronometer could be had for as little as 65 pounds, and he reached that price in part by farming out the manufacture of the simpler components to other tradesmen, reserving his own and his best workers' time for the escapement, the balance and final assembly and rating. The Admiralty's own procurement habits changed to match: a scheme took hold under which a captain who bought his first chronometer privately could have the Admiralty pay for a second, on the reasoning, current by the early nineteenth century, that two chronometers barely improve on one, since a disagreement between them does not say which is wrong. Three, or in FitzRoy's case on the Beagle's second voyage, twenty-two, let a fault be found by majority disagreement instead. None of that fleet-scale redundancy was practical at Harrison's price. It was practical at Earnshaw's.
Chapter 2Two inventions, and a fight over which man made them first
Earnshaw devised his own form of the spring detent escapement and a split-bimetallic temperature-compensation balance in the early 1780s, working to improve the pivoted detent escapement then in use.
Earnshaw devised his own form of the spring detent escapement and a split-bimetallic temperature-compensation balance in the early 1780s, working to improve the pivoted detent escapement then in use. In May 1782 John Arnold, the other leading chronometer maker of the period, was granted a patent that included his own version of a spring detent escapement. Earnshaw's escapement did not receive patent protection until February 1783, and then only in the name of Thomas Wright, watchmaker to the King, who registered the design on Earnshaw's behalf in exchange for a 100-guinea fee and a share of the profits; the punchmark recording Wright's patent was normally removed from Earnshaw's later work once his debt to Wright was repaid, and Sotheby's own specialist cataloguer records that its survival on at least one known movement is unique among catalogued examples.
Earnshaw's own account, published in 1808, is that he had shown his design to friends of Arnold's before Arnold's 1782 patent, and that Arnold's patent absorbed what he had already been shown rather than arrived at the idea independently. Arnold did not live to answer him in print: he died in 1799. Historians of horology remain divided on the underlying question. The technical distinction between the two men's escapements is real and specific: in Arnold's design the detent spring is under tension, pulling the detent away from its rest, and the full length of each escape-wheel tooth slides along the impulse pallet; in Earnshaw's, the spring is under compression, pushing the detent back to rest, and only the tip of each tooth makes contact. Earnshaw's version proved simpler to construct and to service, and it is Earnshaw's form, not Arnold's, that almost every chronometer maker had adopted as the standard by the 1830s. This record does not adjudicate who deserves the credit. It states the positions, names the men who hold them, and records that specialist opinion has not converged in the more than two centuries since.
Chapter 3The Board of Longitude, and a bill that is still being argued
Earnshaw submitted timekeepers to the Board of Longitude from 1791 and competed again in 1793 with the backing of the Astronomer Royal, Nevil Maskelyne.
Earnshaw submitted timekeepers to the Board of Longitude from 1791 and competed again in 1793 with the backing of the Astronomer Royal, Nevil Maskelyne. In an earlier trial, his chronometer no. 265 had outperformed a rival instrument by Josiah Emery, yet failed to win recognition because the Board's rating method measured consistency against the first month's own performance rather than absolute accuracy against a known standard. In 1805, after prolonged argument during which, by the account of the institution he had equipped, his health was nearly broken, Parliament finally granted an award. Two independent sources consulted for this record, the Dictionary of National Biography and Armagh Observatory's own institutional history, both give the figure as 3,000 pounds to Earnshaw. A separate account, in the English Wikipedia's article on Earnshaw, gives a different and unequal split: 2,500 pounds to Earnshaw and 1,672 pounds to "John Arnold's son, John Roger Arnold".
That second account matters because it names the right man. John Arnold senior had died in 1799, six years before this award, and his son John Roger Arnold had run the family firm since 1796. The Dictionary of National Biography's own wording, that the commissioners "granted him and John Arnold 3,000 pounds each", does not specify which Arnold, and Armagh Observatory's history mentions only Earnshaw's own figure without naming a co-recipient at all. This record does not resolve the amount, and does not resolve whether the DNB is using "John Arnold" loosely to mean the surviving firm. It states the disagreement and names where each figure comes from, because a maker's own dispute over money is not well served by a page that quietly picks the tidier of two numbers.
Chapter 4Earnshaw's own case, in his own words
Earnshaw pressed his side of the argument in print twice.
Earnshaw pressed his side of the argument in print twice. In 1806 he published Explanations of Timekeepers constructed by the Author and the late Mr. John Arnold, a title that itself fixes a fact usually left out of the popular account: by 1806 Earnshaw was already writing of his rival in the past tense, seven years after Arnold's death, while the dispute over credit continued to be argued as though between two living competitors. In 1808 he went further, publishing Longitude: an Appeal to the Public, stating T. E.'s Claim to the Original Invention of the Improvements in his Timekeepers, a bound case, with an errata slip, for the priority of his own escapement and compensation balance over Arnold's. A copy of the 1808 pamphlet, later owned by a private collector, was sold at Bonhams in London on 22 November 2011 for 1,062.50 pounds including premium, itself a small data point on how the market still values Earnshaw's own account of the argument alongside his instruments.
The same 1808 pamphlet supplies the most human sentence Earnshaw is recorded as having written about his own work, and it is not about a chronometer at sea. Of a domestic astronomical regulator he had built for a private patron, he wrote plainly: "The best clock I ever made, was for Mr. Larkins of Blackheath."
Chapter 5Whose name is on the clock
The British Museum holds a longcase astronomical regulator, its case signed "Josph.
The British Museum holds a longcase astronomical regulator, its case signed "Josph. Catherwood London", that its own curatorial record attributes not to Catherwood but to Earnshaw. Catherwood is not known to have been anything more than a retailer, and the whole design of the movement and case, in the Museum's own words, points to Thomas Earnshaw as the maker. The dial itself carries physical evidence of the substitution: it was punched out from the back to remove an earlier name before Catherwood's was engraved in its place, and the original name can no longer be read.
A sale catalogue of 23 June 1800, listing the contents of the private observatory of the astronomer William Larkins at Blackheath, describes among its lots "an excellent transit clock, compound pendulum, barometer and thermometer within, in a handsome mahogany case, Earnshaw". The Museum's curator, David Thompson, judges it very likely, though not certain, that this is the same clock Earnshaw named in his 1808 pamphlet as the best he ever made, and that the regulator's composite dial, with its integrated thermometer and mercury barometer, is the only one of its kind known to survive. If the identification is right, the object Earnshaw himself rated as his finest work reached the British Museum carrying, for an unknown stretch of its history, a different maker's name than his own. That is a genuine instance of the trade obscuring a maker's own authorship, on this maker's own account of his best piece, and this record treats the identification exactly as cautiously as the Museum that owns the object does.
Chapter 6Named ships, and one honest failure
Earnshaw's chronometers equipped named Royal Navy and merchant voyages across four decades.
Earnshaw's chronometers equipped named Royal Navy and merchant voyages across four decades. Captain William Bligh bought chronometer no. 1503 for 40 guineas in July 1791, ahead of his second breadfruit expedition to the Pacific and the Caribbean aboard HMS Providence, the voyage that succeeded where his first, aboard HMS Bounty, had ended in mutiny. Matthew Flinders carried two Earnshaw timekeepers, E520 and E543, at 100 guineas each, on HMS Investigator's 1801 to 1803 survey and circumnavigation of Australia, and judged E520 in his own published account "this excellent timekeeper", the only one of his complement still working reliably by the voyage's end. After Flinders was detained by the French at Mauritius on his return, his sailing master, Captain Aken, kept custody of the chronometers and brought E520 back to England in 1805 for return to Greenwich. Its later history went dark until 1937, when the Sydney Technical Museum bought it from a private collector; the connection to Flinders' own voyage was not established until 1976. This publication's own existing record on chronometer no. 509, in the British Museum, covers its four-decade Royal Navy service in detail, including its issue to HMS Beagle in December 1831 for Robert FitzRoy's survey voyage with Charles Darwin aboard, and is not repeated here.
Not every posting ended in credit to the maker. Chronometer no. 512, now at the National Maritime Museum, Greenwich, was East India Company property, issued in 1821 to the Company ship Thomas Grenville under Captain Manning. It performed badly. On the ship's return, Manning was reprimanded for failing to report the fault, and on inspection in 1823 Earnshaw himself, examining his own instrument, stated plainly that it "...cannot be depended upon". The Company's Committee of Shipping recorded that they were "highly displeased" at the delay in reporting the problem and passed a new standing rule requiring every captain to report on his chronometers' performance at the end of each voyage. The museum that now owns the instrument preserves the admission rather than the more comfortable version of the story, and so does this record.
Chapter 7Greenwich, and an astronomer who asked a watchmaker to build a clock
Earnshaw's work reached beyond the sea. He is credited with improving the transit clock at the Royal Observatory, Greenwich, the same institution that would later track chronometer no.
Earnshaw's work reached beyond the sea. He is credited with improving the transit clock at the Royal Observatory, Greenwich, the same institution that would later track chronometer no. 509 by serial number through every one of its postings. When the Astronomer Royal, Nevil Maskelyne, first asked him to build a precision astronomical regulator for the newly founded Armagh Observatory, Earnshaw is recorded as having answered that he did not even know how many wheels went into one; he was, at that point, known chiefly as a watchmaker rather than a clockmaker. He built it anyway. Earnshaw himself installed it at Armagh in 1794, for a purchase price of 100 pounds plus a further 100 pounds to cover his own travel and the installation; the source consulted for this record does not document a prior trial period at Greenwich or give a specific installation date. It incorporated his own escapement design and an airtight case built to keep out dust and draughts, and the Observatory's own director, Thomas Romney Robinson, later judged it the most accurate regulator clock in the world. The Observatory bought a second Earnshaw clock as well, run at sidereal rate alongside its equatorial telescope. Both a wristwatch maker's habitual caution and an institution's own historical record agree that Earnshaw's reputation was not built on the sea alone.
Chapter 8What the market pays now
Signed, numbered Earnshaw pieces move through the trade regularly, and the figures span a wide range depending on completeness, casework and documented history.
Signed, numbered Earnshaw pieces move through the trade regularly, and the figures span a wide range depending on completeness, casework and documented history. At the modest end, Bonhams sold a silver-cased Earnshaw key-wind chronometer pocket watch, no. 3346/757, on 22 February 2023 for 2,805 pounds including premium, and a lot combining an Earnshaw chronometer movement, no. 534, with an unrelated cylinder movement by William Dutton and Sons for 2,250 pounds including premium on 11 June 2013. Sotheby's offered a fine gold pair-cased Earnshaw pocket chronometer of 1801, no. 626/3069, from the Knowles-Brown Collection in its 2017 George Daniels sale with an estimate of 20,000 to 30,000 pounds; the sources consulted for this record do not publish the price it actually made, and this record does not guess at one.
Bonhams' own published results for the lots above give a single inclusive "sold for" figure rather than a hammer price and a separate premium, and this record states that plainly rather than assigning either figure to the wrong column. Where a documented voyage or a named institution attaches to an instrument, value moves sharply: this publication's own record on chronometer no. 509 already establishes that a Beagle-associated instrument by a different maker sold well into six figures once its history was established, a scale no signed Earnshaw watch or movement examined for this record approaches on its signature alone.
Chapter 9A genuine movement, a later case
No source consulted for this record documents an outright forged Earnshaw signature or a chronometer built to deceive as his work.
No source consulted for this record documents an outright forged Earnshaw signature or a chronometer built to deceive as his work. The specific, catalogued risk in the surviving corpus is a quieter one: a genuine movement rehoused, at some later date, in casework it was not made for. Sotheby's 2004 sale of the Time Museum collection catalogued exactly such a piece: a pocket chronometer movement of about 1783, carrying the Wright's patent punchmark from the same arrangement that got Earnshaw's escapement its first patent protection, housed in plain silver inner and outer cases hallmarked London 1805, twenty-two years after the movement itself was made. The cataloguer's own note observed that the punchmark survives on this example almost uniquely among known Earnshaw watches, since it was normally removed from later work once the debt to Thomas Wright was repaid. Nothing about the piece was presented as fraudulent; it was catalogued exactly as what it is, an authentic early movement in a later case. That is precisely the pattern the wider antique-chronometer trade warns buyers to check for on any instrument of this age and value, and this is the one specific, sourced instance of it found for this record.
Chapter 10Death, memory, and a name resold
Earnshaw died at his home in Chenies Street, Bedford Square, on 1 March 1829, aged eighty, and was buried at St Giles-in-the-Fields in Bloomsbury.
Earnshaw died at his home in Chenies Street, Bedford Square, on 1 March 1829, aged eighty, and was buried at St Giles-in-the-Fields in Bloomsbury. No source consulted for this record documents a successor firm carrying his name forward, in contrast to Arnold's business, which continued under his son as Arnold and Dent and went on servicing Navy chronometers, including no. 509 itself, for decades after both founders were dead. The Worshipful Company of Clockmakers and the British Horological Institute placed a brass memorial plaque to him at St Giles-in-the-Fields, a date of 1929 for it recorded in this record's own source list though not independently confirmed against a source documenting this specific object, and the site of his Holborn workshop, opposite the modern entrance to Holborn Underground station, is separately marked today by a London County Council plaque.
The name itself outlived any continuation of the actual business. A watch brand trading as Thomas Earnshaw, founded in 2012 and unconnected to the historical workshop or to any documented descendant of it, now sells accessible mechanical watches, describing itself on its own website as named after "the legendary watchmaker whose timepieces helped guide Charles Darwin's voyage around the world" and inspired by the "Father of the Modern Chronometer". The description is not inaccurate as a piece of marketing. It is worth separating clearly from the eighteenth-century maker's own workshop and instruments, precisely because the two are otherwise easy for a search engine, and a careless reader, to run together.
What is documented
Two names for the same trade
The workshop
A hard start, left out of the standard account
Married and fathered three sons before finishing his apprenticeship; faced debtors' prison in 1774, fled briefly to Ireland, and returned to surrender at the Fleet. Did not clear his debts and establish the workshop that made his name until about 1780.3
The two inventions
His own form of the spring detent escapement (compression, tip-contact) and a split-bimetallic temperature-compensation balance, both devised in the early 1780s and, in the judgement of the specialist literature, adopted as essentially the universal standard in marine chronometers from his own lifetime onward.13
Cheapness as the achievement
A new boxed Earnshaw chronometer cost as little as 65 pounds by the 1780s, against roughly 450 pounds for Larcum Kendall's careful copy of John Harrison's design. The Dictionary of National Biography's own summary credits Earnshaw with making precision timekeeping "simple and cheap" enough for ordinary buyers, not only for state-funded voyages.23
The Arnold rivalry
A priority dispute over the spring detent escapement, argued in print by Earnshaw himself in 1806 and 1808, and never resolved by the Board of Longitude, which split its 1805 award rather than crediting either man alone. Sources disagree on the exact sums and even, arguably, on which Arnold received the money, since John Arnold senior had died in 1799.12321
An admitted failure
Chronometer no. 512, issued to the East India Company ship Thomas Grenville in 1821, performed badly enough that Earnshaw himself, on inspecting it in 1823, judged it could not be depended upon.6
Death and memory
Died 1 March 1829 at Chenies Street, Bedford Square, aged eighty; buried at St Giles-in-the-Fields. A brass memorial plaque naming him was placed at St Giles-in-the-Fields by the Worshipful Company of Clockmakers and the British Horological Institute; this record could not independently confirm the plaque's date or erecting bodies against a source that actually documents this specific object, and states that gap rather than repeating an unconfirmed claim as settled.222
Technique
Marine and pocket chronometer escapement
Earnshaw's own form of the spring detent escapement: the detent spring under compression, pushing the detent back to its rest, and only the tip of each escape-wheel tooth making contact with the impulse pallet. Distinct from Arnold's competing design, in which the spring is under tension and the full length of each tooth slides along the pallet.13
Compensation balance
Split-bimetallic temperature-compensation balance with moveable weights screwed to the split rims, and a free-sprung helical blued-steel balance spring, used across his marine and pocket chronometers.3
A second, distinct escapement for astronomical regulators
His domestic longcase regulators, including the Larkins/Catherwood clock, used his own version of Thomas Mudge's gravity escapement rather than the spring detent escapement of his marine work; the British Museum's own example is, in its curator's words, the earliest surviving instance of Mudge's detached gravity escapement known.4
Casework
Marine chronometers housed in a rectangular mahogany box on brass gimbals, lined with green baize, with a glazed viewing aperture, sliding cover and an inserted ivory disc in the lid; astronomical regulators in tall mahogany cases, in at least one documented example combined with an integrated thermometer and mercury barometer in the dial itself.34
Production method
Simpler components farmed out to other tradesmen for manufacture, with Earnshaw and his most skilled workers reserved for the escapement, balance and final assembly and rating, a division of labour credited with making his instruments producible in quantity at a price no single-master workshop could match.3
The surviving work
- What is accepted
- Every instrument carrying Earnshaw's stamped serial number and one of his two documented signature forms, on the movement and again on the dial, is treated by the institutions holding them, and by the trade, as an authentic product of his workshop; this is not seriously disputed the way an unsigned painting's authorship is. Individually documented surviving examples span at least serial numbers 245 to above 3979, held today at the British Museum, the Worshipful Company of Clockmakers' Museum, the National Maritime Museum at Greenwich, the Science Museum Group, the Smithsonian's National Museum of American History, the Powerhouse Museum in Sydney and in private hands. No source consulted for this record publishes a verified total count of everything his workshop made.
- What is contested
- The one documented case of disputed authorship found for this record is not a doubt about Earnshaw's hand but about a name deliberately put in its place: the British Museum's longcase regulator is signed "Catherwood", a retailer with no known workshop of his own, over a dial physically altered to remove an earlier, now illegible name before Catherwood's was engraved. The Museum's own curator, David Thompson, reattributes the piece to Earnshaw on the strength of the movement and case design and a matching description in an independent 1800 sale catalogue.
- Who rules on attribution
- No single board or foundation rules on Earnshaw attributions the way some painters' estates or catalogue committees do. Attribution rests on the stamped serial number and signature, cross-checked where the instrument saw Navy service against the Royal Observatory, Greenwich's own ledger of chronometer issues, and on institutional curatorial judgment, most visibly exercised in print by David Thompson at the British Museum and by Jonathan Betts, former curator of horology at the Royal Observatory, Greenwich. The Antiquarian Horological Society's own journal is the principal venue where such judgments are argued and published.
Catalogue raisonne
- Jonathan Betts, Marine Chronometers at Greenwich: A Catalogue of Marine Chronometers at the National Maritime Museum, Greenwich (Oxford University Press, 2018). The standard modern scholarly catalogue of chronometers held at the National Maritime Museum, covering makers across the whole tradition rather than Earnshaw's output specifically; the fifth and largest in a series of National Maritime Museum instrument catalogues. No source consulted for this record identifies a catalogue devoted specifically and solely to Earnshaw's own production.16
- Rupert T. Gould, The Marine Chronometer: Its History and Development (J. D. Potter, 1923). The founding modern historical survey of the marine chronometer, covering Harrison, Arnold and Earnshaw together; still cited as a primary reference in current specialist literature.1
- Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum, Vol. VI (1990). The catalogue entry underlying the British Museum's own published curatorial description of chronometer no. 509, quoted directly on the Museum's collection page.3
- Thomas Earnshaw, Explanations of Timekeepers constructed by the Author and the late Mr. John Arnold (1806) and Longitude: an Appeal to the Public, stating T. E.'s Claim to the Original Invention of the Improvements in his Timekeepers (1808). Primary self-documentation rather than an independent catalogue; Earnshaw's own case for what he made and why it preceded Arnold's work.219
...cannot be depended uponThomas Earnshaw, on inspecting his own chronometer no. 512 in 1823, quoted by the National Maritime Museum, Greenwich in its own published object record. A rare instance of the maker judging one of his own instruments a failure, preserved rather than smoothed over by the institution that now owns it.
Questions about Thomas Earnshaw
Who was Thomas Earnshaw?
Chronometer maker; Watchmaker. 1749-1829.
When did Thomas Earnshaw live?
Born 4 February 1749, Ashton-under-Lyne, Lancashire, England; died 1 March 1829, Chenies Street, Bedford Square, London. Buried at St Giles-in-the-Fields, Bloomsbury.
How are fakes and misattributions of Thomas Earnshaw detected?
A pocket chronometer movement of about 1783, carrying the Wright's patent punchmark, rehoused in plain silver inner and outer cases hallmarked London 1805. Sold by Sotheby's in its 2004 Time Museum sale as a catalogued, honestly described example of an authentic Earnshaw movement in later casework, twenty-two years newer than the movement itself. The punchmark, from the arrangement under which Thomas Wright held Earnshaw's first patent, was normally removed from Earnshaw's later work once his debt to Wright was repaid, which the cataloguer states makes its survival on this particular movement unique among known examples.
Where can you see work by Thomas Earnshaw?
British Museum (London); Worshipful Company of Clockmakers' Museum (London); National Maritime Museum, Royal Museums Greenwich (London); Science Museum Group (London); Smithsonian, National Museum of American History (Washington, D.C.); Powerhouse Museum (Sydney, Australia).
What does the market for Thomas Earnshaw look like?
Prices for signed Earnshaw pieces span a wide range. At the lower end of the trade, a silver-cased Earnshaw key-wind chronometer pocket watch made 2,805 pounds including premium at Bonhams in February 2023, and a lot pairing an Earnshaw movement with an unrelated Dutton movement made 2,250 pounds including premium in 2013.
What is still unresolved about Thomas Earnshaw?
Did the Board of Longitude's 1805 award actually go to John Arnold himself, who had been dead six years, or to his son and successor John Roger Arnold? The Dictionary of National Biography and Armagh Observatory's own account both give the figure as 3,000 pounds to Earnshaw without naming a co-recipient clearly; a separate account gives Earnshaw 2,500 pounds and names John Roger Arnold as receiving 1,672 pounds.
Open questions
- Did the Board of Longitude's 1805 award actually go to John Arnold himself, who had been dead six years, or to his son and successor John Roger Arnold? The Dictionary of National Biography and Armagh Observatory's own account both give the figure as 3,000 pounds to Earnshaw without naming a co-recipient clearly; a separate account gives Earnshaw 2,500 pounds and names John Roger Arnold as receiving 1,672 pounds. The sources consulted do not agree, and this record does not choose between them.
- How many marine chronometers, deck watches and pocket chronometers did Earnshaw's workshop produce in total, and did one serial-number series cover all of them or several run in parallel? Individually documented examples span at least numbers 245 to above 3979, but no source consulted for this record publishes a verified total or resolves the numbering scheme.
- Can the priority dispute with John Arnold over the spring detent escapement be resolved at this distance? Specialist opinion remains divided, and this record does not adjudicate it.
- Is the British Museum's Catherwood-signed longcase regulator definitely the clock Earnshaw called the best he ever made, built for William Larkins of Blackheath? The Museum's own curator calls the identification very likely rather than certain, on the strength of a matching 1800 sale-catalogue description rather than a document naming the clock directly.
- What became of Earnshaw's stock, tools and business after his death in 1829? No source consulted for this record documents a successor firm or a dispersal sale, in contrast to the well-documented continuation of Arnold's firm as Arnold and Dent.
- What price did the Sotheby's 2017 gold pair-cased pocket chronometer, estimated at 20,000 to 30,000 pounds, actually realize? Not published in the source consulted for this record.
Sources
- 1Wikipedia, "Thomas Earnshaw": biography, the two inventions, the Arnold priority dispute, the 1805 Board of Longitude award figures, documented voyages including Bligh's Providence and Flinders' Investigator. en.wikipedia.org/wiki/...
- 2Dictionary of National Biography, 1885-1900, "Earnshaw, Thomas", via Wikisource: birth and death dates and places, apprenticeship, the Holborn workshop, the 1793 Board of Longitude submission backed by Maskelyne, the 1805 award of 3,000 pounds to both Earnshaw and "John Arnold", the 1806 and 1808 publication titles, the Bellin engraving after Shee. en.wikisource.org/wiki/...
- 3British Museum, Collection Online, "marine chronometer", museum number 1958,1006.1957: full object description, inscriptions, curator's comments quoting David Thompson, Clocks (2004) and Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum, Vol. VI (1990), including Earnshaw's early biography, debt and flight to Ireland, and the chronometer's Royal Navy service through to HMS Beagle. britishmuseum.org/collection/...
- 4British Museum, Collection Online, "double-dial clock; long-case clock; regulator; weight-driven clock; clock-case; barometer; thermometer", museum number 1989,0307.1: full object description and curator's comments quoting David Thompson, Clocks (2004) p.124, on the Catherwood signature, the punched-out dial, the 1800 Larkins sale catalogue, and the exhibition "Arnold & Earnshaw, Pioneers of the Chronometer" (National Maritime Museum, 1998-1999). britishmuseum.org/collection/...
- 5Royal Museums Greenwich, Collections, "Thomas Earnshaw, 1749-1829" (portrait, object BHC2674): sitter, artist Martin Archer Shee, date, dimensions, credit line (Caird Fund). rmg.co.uk/collections/...
- 6Royal Museums Greenwich, Collections, "512" (marine chronometer): East India Company service, issue to the ship Thomas Grenville in 1821, Earnshaw's own 1823 admission that it "cannot be depended upon", the Company's reprimand and new reporting rule, and its 1936 purchase by Sir James Caird for 16 pounds. Footnotes Philip Arnott, "Chronometers on East India Company Ships 1800 to 1833", Antiquarian Horology, Vol. 30 No. 4, December 2007. rmg.co.uk/collections/...
- 7Wikimedia Commons, file and for File:Thomas Earnshaw, 1749-1829 RMG BHC2674.tiff: licence Public domain, artist Martin Archer Shee, credit National Maritime Museum, Greenwich via collections.rmg.co.uk. commons.wikimedia.org/wiki/...
- 8Wikimedia Commons, file and for File:Longcase regulator, by Thomas Earnshaw, London, c. 1795 - British Museum - DSC00078.jpg: licence CC0, photographer Daderot. commons.wikimedia.org/wiki/...
- 9Wikimedia Commons, file and for File:Marine chronometer by Thomas Earnshaw, London, c. 1800 - Clockmakers' Museum - London, UK - DSC05419.jpg: licence CC0, photographer Daderot. commons.wikimedia.org/wiki/...
- 10Britten, 1896. commons.wikimedia.org/wiki/...
- 11Wikimedia Commons, file and for File:THOMAS EARNSHAW - 119 High Holborn Holborn London WC1V 6RD.jpg: licence CC BY-SA 4.0, photographer Spudgun67. commons.wikimedia.org/wiki/...
- 12Wikimedia Commons, category page "Category:Thomas Earnshaw", listing all files in this category, cross-checked to confirm no further genuine, licence-clear images were overlooked; also London Remembers, "Thomas Earnshaw": burial place, plaque locations, and a compiler's characterisation of Earnshaw as difficult to deal with in business. londonremembers.com/subjects/...
- 13Wikimedia Commons, file and for File:St Giles in the Fields, Thomas Earnshaw memorial.jpg: licence CC BY-SA 4.0, photographer AndyScott. commons.wikimedia.org/wiki/...
- 14Sotheby's, "Masterpieces from the Time Museum" (2004), lot 624 (the Wright's patent punchmark movement recased in 1805; url given). A second lot, "George Daniels: 20th Century Innovator" (2017), lot 47, an 1801 gold pair-cased pocket chronometer no. 626/3069 with a 20,000 to 30,000 pound estimate and Knowles-Brown Collection provenance, is also cited for that figure; its own URL is not recorded in this file and should be re-sourced directly on a future pass. sothebys.com/en/...
- 15Wikimedia Commons, file and for File:Thomas Earnshaw.jpg: licence public domain (by age), sourced originally from English Wikipedia, described as an engraved reproduction of the Shee portrait. commons.wikimedia.org/wiki/...
- 16Jonathan Betts, Marine Chronometers at Greenwich: A Catalogue of Marine Chronometers at the National Maritime Museum, Greenwich (Oxford University Press, 2018). Cited for its role as the standard modern catalogue of the National Maritime Museum's chronometer holdings; not itself directly consulted page-by-page for this record, and flagged for a researcher to check directly for any further Earnshaw entries. google.com/books/...
- 17Bonhams, sale 28031, lot 11, "Thomas Earnshaw, London. A silver key wind open face chronometer pocket watch, London Hallmark for 1879": sold 22 February 2023 for GBP 2,805 inc. premium. bonhams.com/auction/...
- 18Bonhams, sale 20747, lot 91, "A lot of two interesting pocket watch movements including a chronometer movement by Thomas Earnshaw and a cylinder movement by William Dutton & Sons": sold 11 June 2013 for GBP 2,250 inc. premium. bonhams.com/auction/...
- 19Bonhams, sale 18992, lot 437, "EARNSHAW (THOMAS) Longitude. An Appeal to the Public Stating Mr. Thomas Earnshaw's Claim to the Original Invention of the Improvements in His Timekeepers, F. Wingrave, 1808": full title, condition, sold 22 November 2011 for GBP 1,062.50 inc. premium. bonhams.com/auctions/...
- 20Powerhouse Collection, "Matthew Flinders marine chronometer" (chronometer E520): its 1801 manufacture, service on HMS Investigator, capture and recovery, 1937 acquisition by the Sydney Technical Museum, and 1976 identification. collection.powerhouse.com.au/object/...
- 21Armagh Observatory and Planetarium, "The Earnshaw Clocks": Maskelyne's commission, Earnshaw's own admitted ignorance of clockmaking at the outset, the 1794 installation, the 100-pound purchase and 100-pound travel fee, Thomas Romney Robinson's assessment, and the 3,000-pound Parliamentary award following testimony from Robinson's predecessor and Maskelyne. armagh.space/heritage/...
- 22London Remembers, "Thomas Earnshaw": death at Chenies Street, burial at St Giles-in-the-Fields, and the separate London County Council workshop-site plaque. This source does not itself document the St Giles-in-the-Fields brass memorial plaque's date or erecting institutions; those details are carried in this file from an unconfirmed source and flagged as such at each point they appear. londonremembers.com/subjects/...
- 23Thomas Earnshaw (modern watch brand), "About Us": states the brand was founded in 2012 and describes itself as named after and inspired by the historical maker. Cited only for the fact of the modern brand's existence and its own stated relationship to the historical figure; not used for any fact about the eighteenth-century maker himself. thomas-earnshaw.com/pages/...
Cite this pageIconotheca, “Thomas Earnshaw”, The Provenance Record, iconotheca.com/artists/thomas-earnshaw/, version of .
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