Mr. Cox’s Perpetual Motion • A Mechanical and Philosophical Time Piece • So Capital a Performance

Mr. Cox’s Perpetual Motion, a Prize in the Museum Lottery, single sheet, 225mm. x 174mm., full-page engraving with letterpress on verso, London, 1774. (Ex) Item 4848706

James Cox (c1723—1800) was a noted clockmaker, and developed this ingenious timepiece in the 1760’s in collaboration with John Joseph Merlin (with whom Cox also worked on developing automata). Cox believed that his design was a true perpetual motion machine, but in fact it was powered from changes in atmospheric pressure via a mercury barometer. This provided sufficient movement of the winding mechanism to keep the mainspring coiled inside the barrel. The clock was designed to enable the timepiece to run indefinitely and over-winding was prevented by a safety mechanism.

He exhibited the clock at his Museum in Spring Gardens, Charing Cross, London, and as with other such marvels, it was accompanied by extravagant literary puffs to ensure public attention, and promote revenue from ticket sales. Cox’s Exhibition was the talk of London when it opened in 1772; a riot of brilliance, movement and sound, and an accumulation of bejeweled automata valued then at an enormous sum of £197,000. It was recommended by Johnson, visited by Boswell, featured in Fanny Burney’s Evelina and Sheridan’s The Rivals. “A peacock (now in the Hermitage, Leningrad) screeched and spread its tail when the hour struck, while a cock crowed and a cage with an owl inside revolved and twelve bells rang. A silver swan with an articulated neck glided across a surface of artificial water.., sixteen elephants supported a pair of seven-foot high temples adorned with 1,700 pieces of jewelry… a chronoscope inlaid with 100,000 precious stones evidently needed no animal guise.” (See: Richard Altick, The Shows of London, p. 69-72, 350-351, for a long and detailed account of Cox and his exhibition.)

Cox charged admission at the unprecedented rate of 10s. 6d, and the Catalogue was first issued March 2nd 1772, as a 20-page quarto edition. Such was the grumbling amongst even his most well-heeled clients that he was forced to cut the admission price by half to one quarter of a guinea and reduce the size of the catalogue. In 1773 an Act of Parliament was passed “allowing James Cox to dispose of his museum pieces by lottery”, and it is likely that this handbill was printed to promote the sale of this particular exhibit. The verso contains a full description of the piece, as well as a testimony as to its ingenuity by the noted astronomer James Ferguson, dated January 28th, 1774.

A note in Cox’s commonplace book, dated 1769, is the first recorded reference to the clock. It was purchased in the lottery by Thomas Weeks, who opened “Week’s Mechanical Museum” at 3 & 4 Tichborne Street, and after adding his own embellishments, exhibited it until his death in 1833. It was not included in the sale catalogue of his effects in 1834, and remained lost until 1898 when it was exhibited at the Clerkenwell Institute. After a period on loan to the Laing Gallery in Newcastle, is was auctioned, and then finally acquired by the V & A Museum in 1961. The engraving is recorded, occurring as a plate in The London Magazine for February 1774; but this hand-bill is unrecorded by ESTC. [This text supplied by Alex Fotheringham.]

5 thoughts on “Mr. Cox’s Perpetual Motion • A Mechanical and Philosophical Time Piece • So Capital a Performance

  1. My goodness, this is a fascinating book. May I ask where you found it? I’m sure there is a very interesting story behind just the discovery!

  2. Very interested in Alex Fotherinham’s comments on Cox, particularly the reference to Cox’s Commonplace Book, dated 1769. Alex, can you tell me where this common day book is located?

    I am researching James Cox and have an extensive biography of him, but no knowlege of any common day book.

    Ian White
    Portsmouth ENGLAND

  3. My GGGG Grandfather was a watchmaker called Thomas WEEKS. He may be related to the Thomas WEEKS of “Weeks’ Mechanical Museum” I would be very interested to find out who sold Mr. Cox’s Perpetual Motion after it was in Weeks’ Museum.


  4. My grandfather was Charles Cox b.1862, his father another Charles b. 1830s, his father James Cox married a Mary Anne Dudley Gough in St Peters Islington in about 1828. Do not know if they are connected to the clockmaker but my grandmother had a communication from a Spring Gardens solicitor during first World War over some property there! Would be interested to know if you have discovered anything?

  5. This is very interesting,was this the beginning of the ATMOS clock era?I have a Antique Clock Repair Business in Boone nc.I am intrested also,because I have two James Coxs in my family genoligy.I have worked on and repaired Atmos Clocks.Very nice workmanship.Any comments or replies welcome. Cordially:GRC

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