# Marine Timekeeper known as H5 > John Harrison and Son, London - 1770 (movement signed and dated); tested and completed for its documented purpose in 1772 > Canonical HTML: https://iconotheca.com/artworks/john-harrison/harrison-h5-marine-timekeeper-clockmakers/ > Published by Servola Systems GmbH. Last verified: 2026-09-03 ## Tombstone - **Artist:** John Harrison and Son, London - **Date:** 1770 (movement signed and dated); tested and completed for its documented purpose in 1772 - **Medium:** Silver, gold, enamel, ivory, diamond, brass and steel; silver pair case; mahogany carrying case with silk cushions - **Dimensions:** Not published in the Science Museum Group catalogue entry consulted for this record. Recorded here as unverified rather than guessed; H4, the closest comparator, has a dial diameter of 102 mm and overall case dimensions of 165 x 124 x 28 mm, and H5 is described in every source consulted as very similar in form, but that is not the same as a measurement of H5 itself. - **Object type:** Clocks and instruments - **Period:** English, 1770 - **Current location:** Science Museum, London, Clockmakers' Museum gallery; the object is owned by the Worshipful Company of Clockmakers and lent to the Science Museum Group - **Attribution:** accepted ## Summary The watch that finished an argument the Board of Longitude refused to finish itself. John Harrison built H5 after 1765, while his prize-winning H4 sat confiscated in the Astronomer Royal's custody, because he had come to feel, in his own words, extremely ill used by the gentlemen he might have expected better treatment from. In 1772 King George III tested H5 personally at his private observatory for ten weeks and found it accurate to within a third of a second a day, then told Harrison to petition Parliament directly. A special Act paid him 8,750 pounds in 1773, about 44 percent of the 20,000 pound prize the 1714 Act had promised and never once paid out in full to anyone. Harrison was eighty.H5 stayed with the Harrison family, never went to sea, and never became government property the way H1 to H4 did. It now belongs to the Worshipful Company of Clockmakers and is shown at the Science Museum's Clockmakers' Museum, a different institution and a different owner from the four machines at Greenwich that most accounts of Harrison's life fold it into without noticing the difference.This record starts from a narrower problem than most: whether the one candidate photograph of H5 available under a free licence actually shows H5 at all, rather than H4, which looks similar enough by design to invite exactly that mistake. ## Provenance Every link carries a grade. `documented` means a cited source supports it, `disputed` means the identification is argued but not established, `unknown` means we have no owner for that span and have not bridged it. - **1770-1772** John Harrison, and his son William Harrison `[documented]` (manufacture and private testing) Built in London and signed on the movement 'John Harrison & Son London 1770 No. 2'. Made after the 1765 Act had already confiscated H4, while Harrison, then in his mid-seventies, was still contesting the Board of Longitude's refusal to treat H4's Barbados trial as conclusive proof. No source consulted documents a commission or a buyer for H5; it was made at Harrison's own initiative and remained his personal property. - **1772** King George III, on loan for testing `[documented]` (royal trial) Harrison obtained an audience with the King, who tested H5 himself at his private observatory near Richmond over ten weeks of daily observation between May and July 1772, and found it accurate to within one third of a second per day. How the audience was arranged, and whether an intermediary was involved, is not stated in any source consulted for this record. - **1772-1776** John Harrison `[documented]` (return to owner, and Harrison's death) H5 was returned to Harrison after the royal trial; it was never surrendered to the Board of Longitude and never became government property, unlike H1 to H4. Harrison received 8,750 pounds from Parliament in June 1773 and died on 24 March 1776. No source consulted for this record states who held H5 at the moment of his death. - **1776** Unknown intermediate hands `[unknown]` (gap) No source consulted for this record documents how H5 passed from Harrison's estate, through whatever hands it passed through, into the ownership of the Worshipful Company of Clockmakers. The Company's own published museum history and the Science Museum Group's catalogue entry for the object both stop at stating current ownership; neither gives a date or a mechanism (purchase, gift, bequest) for the acquisition. This is a genuine and, on the evidence gathered here, an unresolved gap of at least several decades. - **-2015** Worshipful Company of Clockmakers `[documented]` (long-term custody, Guildhall display) The Company's Clockmakers' Museum was first established in 1813-14 and was housed at the Guildhall, London, from 1874 to 2014, making it, on the Company's own account, the oldest specific collection of clocks and watches in the world. H5 is listed among the collection's notable pieces. The exact date H5 joined the collection, as against the collection's founding date, is not given in the sources consulted. - **2015-present** Worshipful Company of Clockmakers, on loan to the Science Museum Group `[documented]` (relocation and current display) The Clockmakers' Museum gallery at the Science Museum, South Kensington, was officially opened by Princess Anne on 22 October 2015. H5 is catalogued there as Science Museum Group object L2015-3480, with the Company retaining ownership and the Museum holding it on loan. It is a stated highlight of the gallery's guided tours. ## Open questions - How and when did H5 pass from Harrison's estate into the ownership of the Worshipful Company of Clockmakers? No source consulted for this record gives a date or a mechanism (purchase, gift, bequest) for this transfer, a gap of at least several decades after Harrison's death in 1776. - How did Harrison obtain his audience with George III in 1772? No source consulted names an intermediary or describes how the meeting was arranged. - Is the quotation 'By God, Harrison, I will see you righted' genuinely attributable to George III, and if so, on what primary source? This record could not trace it and has recorded it as an unverified popular anecdote. - Was Harrison's own 1920s-1933 restorer, Rupert Gould, ever involved with H5, given that he is documented as restoring 'the marine chronometers of John Harrison' without a source specifying whether that phrase covers H1 to H4 only (the Board of Longitude group at Greenwich) or H5 as well, which the Company, not the Board, owned throughout. - What was H5's exact case and dial measurement (height, width, depth, weight)? Not published in the Science Museum Group catalogue entry consulted for this record. - Precisely which building was 'the King's private observatory near Richmond' where the 1772 trial took place? Sources consulted give slightly different phrasing (one refers to testing 'at the palace'), and this record found no source that names a specific structure and confirms the 1772 trial took place there by name. ## Sources - [1] Science Museum Group Collection, 'Marine Timekeeper known as H5 by John Harrison and Son 1770'. Object number L2015-3480, Clockmakers' Museum No. 598. Source for the case, dial, movement, materials, inscription, accessories, credit line, and the Museum's own statement that H5 is mechanically very similar to H4. - [2] Wikimedia Commons, file description page and API metadata (extmetadata.LicenseShortName) for File:Harrison's Chronometer H5.JPG. Source for the upload history, the uploader's own unsourced description, the categories, and the CC BY 2.5 / CC BY-SA 3.0 dual licensing. This record's identification check began from the fact that this page provides no museum reference for the identification. - [3] Wikipedia, 'John Harrison'. TERTIARY, flagged for replacement with the Board of Longitude's own papers and Ruth Burkholder's 1983 article. Source for the Board's stated reasons for refusing H4, the 1765 Act terms, the 1772 Richmond trial and its ten-week duration and one-third-second accuracy, the 1773 Act and the 8,750 pound award, Harrison's lifetime total of 23,065 pounds, the 'extremely ill used' quotation (citing Burkholder, Ruth, 'Solving the Problem of Longitude', Cook's Log 6(4), 1983, pp. 222-224), the Maskelyne rivalry and the lunar-distance method, Harrison's musical tuning pamphlet and the 2002 Library of Congress manuscript discovery, and his death on 24 March 1776 at a stated age of eighty-two. - [4] Wikipedia, 'Board of Longitude'. TERTIARY, flagged for replacement with the Board's own minutes. Source for the statement that the 20,000 pound prize was never awarded to Harrison or to anyone else in the form the 1714 Act described, and for the Board's abolition in 1828. - [5] Wikipedia, 'Worshipful Company of Clockmakers'. TERTIARY; the article itself carries a maintenance notice that it relies excessively on primary sources. Source for the 1813-14 founding of the collection, its description as the oldest specific collection of clocks and watches in the world, the 1874-2014 Guildhall display period, the move to the Science Museum opened by Princess Anne on 22 October 2015, and the statement that H5 is part of the collection, without an acquisition date. - [6] Worshipful Company of Clockmakers, own website, Museum Collection page. Source for the Company's own listing of H5 as a notable collection piece, the approximate size of the current gallery (around 720 objects), and the statement that the Company is working with the Science Museum to digitise and photograph the collection. - [7] Antiquarian Horological Society, 'Inspiring people with horological collections: a guide's perspective'. Source for the description of visitors becoming 'fixated by H5' on guided tours of the Clockmakers' Museum gallery at the Science Museum, and for the museum's monthly tour programme running since July 2019. - [8] Royal Museums Greenwich, 'Harrison's clocks and the longitude problem'. Source for cross-reference detail on H4, Maskelyne's role in the Barbados trial and his custody of the confiscated timekeepers from 1766, used here to place H5 correctly outside the Greenwich group. This story page does not itself cover H5. - [9] Wikipedia, 'Rupert Gould'. Source for Gould's 1920-1933 restoration of 'the marine chronometers of John Harrison', which this record notes does not specify by name whether H5 was included, since H5 was never Board of Longitude or National Maritime Museum property. - [10] Wikipedia, 'King's Observatory'. Consulted to check the identity of 'the King's private observatory near Richmond'; this article, about the observatory built in 1769 at Kew within Richmond parish, does not itself mention Harrison, H5, or the 1772 trial, and its documented role testing chronometers is dated to the 1850s, decades later. This record therefore does not assert that this specific building was the site of the 1772 trial. - [11] Wikimedia Commons API and file description pages, used to verify extmetadata.LicenseShortName for every plate proposed in this record: the Thomas King portrait of Harrison (public domain), the Colonel Warden photograph of H4 (CC BY-SA 3.0), the Allan Ramsay portrait of George III via Google Art Project (public domain), the Wellcome Collection engraving of Nevil Maskelyne (CC BY 4.0), and the Marcus Cornish statue photograph (CC BY-SA 4.0). Also used to confirm that the Science Museum Group's own eight photographs of H5 are released under CC BY-NC-SA 4.0, a non-commercial licence not used in this record's gallery. --- Images on this record are public domain or CC0 and are hosted by us. No image on this site is generated or simulated. If you quote this record, quote the provenance grades with it.