Georgian Black Glass Artificial Horizon by Thomas Jones of London

For sale, a George III black glass artificial horizon by Thomas Jones of Charing Cross London.

This early example, is contained within a fitted mahogany case with hinged lid and hook and eye catches to the front. The inside of the lid retains its superb and original trade label for, “Thomas Jones (pupil of Ramsden), Astronomical and philosophical instrument maker to His Royal Highness The Duke of Clarence, 62 Charing Cross, London”. The exterior of the lid has a further paper label which contains writing which is now unfortunately obscured but seems to suggest an original owner.

The horizon is comprised of a solid brass tray with three adjustable screw feet for the purpose of levelling the instrument. The central section is routed out and fitted with a rectangular black glass plate which provides the reflective surface required for its operation.  The underside is further engraved to, “Thomas Jones, 62 Charing Cross, London”. The bubble level provided with the instrument does not look original but is certainly a contemporary replacement consisiting of a glass cylinder enclosed at the top with sealing wax and a pearl like ball which moves freely within.

The history of the artificial horizon can be traced back to the sixteenth century but developments were largely popularised in the eighteenth century by John Hadley, John Elton and by the famous instrument maker, George Adams, the latter of whom is merited in 1738 with inventing the mercury trough of which this is a development intended to avoid the shake of the mercury encountered during the motion of a ship. It was devised as a means of navigation when the horizon was obscured by darkness or through the effect of inclement weather.

Its principle was based upon the first law of optics, that the angle of reflection from a mirror is equal to the angle of incidence, therefore a sextant would be employed to measure the angle between the sun or the stars and their reflection on mercury or a glass plate.

The maker Thomas Jones (1775 – 1852) was a superior maker of scientific instruments. Apprenticed to eminent maker of the period, Jesse Ramsden from 1789-1796 at a cost of 50 guineas, Jones continued to work for Ramsden until his death in 1800. Most sources have the firm’s working dates as starting in 1806 and references to work undertaken for Edward Troughton during this period would suggest that he worked as a jobbing instrument maker for the six years prior to opening his first premises in Mount Street. The history of the firm of Troughton & Simms also relates that Jones whilst working for Ramsden, provided the young William Simms with a supporting letter to The Royal Society for Simm’s “improved protractor” so we can be sure that a good working relationship existed. His first year of trading brought Jones’s first success in a commission from Mr HC Englefield to manufacture his new portable or “mountain barometer”. Englefield wrote that he had,

“Employed Mr Thomas Jones, of number 120 Mount St, Berkeley Square, pupil of the late Mr Ramsden, and who will furnish them at the price of two guineas and a half with the attached and detached thermometer”.

The barometer (although very rarely found on the market today) proved extremely popular, so much so that Jones wrote a pamphlet eleven years later in 1817 entitled, “A companion to the Mountain Barometer” wherein he states that “since its introduction in 1806 he had sold between 300 and 400 of these instruments”. It is also interesting to note that Jones signs himself off as, “Astronomical and philosophical instrument maker to his Royal Highness the Duke of Clarence” in this publication so he must have held the Royal Appointment for at least twenty years until William IV eventually died.

(Note: I have an Edward Troughton (pre-Troughton & Simms) Mountain Barometer of this type currently for sale if the reader is interested to see an example. It is of course possible that Jones may have made this for Troughton under contract, given his relationship to him).

In 1811, a further move was undertaken to Oxenden Street in Piccadilly by which time Jones had already patented his own dividing engine for the manufacture of scientific scales and had written his first publication in 1814 entitled, “Description & Use of the Sectograph”. Shortly afterwards he finally moved to his famous Charing Cross address in 1816. Jones was known as “Jones of Charing Cross” to distinguish him from his equally famous competitors, W&S Jones of Holborn.

In 1819, the successor to Ramsden’s business Matthew Berge died and Jones is documented as sending a letter to the Board of Longitude requesting that the circular and straight line dividing engines originally manufactured by Ramsden and owned by the Board, be entrusted to him. Jones had applied in the same manner after Ramsden’s death but Berge had been granted stewardship of the instruments at this point and was probably the catalyst for Jones’s patenting his own dividing engine. On this second attempt however, he was successful in gaining control of the straight line engine although the circular was then considered to have become somewhat inaccurate by that time so it was left for further consideration (It was later given to Worthington, another of Ramsden’s acolytes). This seemingly small insight is useful in our understanding of just how important a figure Jones was at the time. Not only would he have gained work from a leading scientific body who entrusted him with such an important instrument but he would also have brought in a swift trade from the rest of the London trade in providing accurate scales for use in their own manufacture.

His costs were, “varied from 3 shillings and six pence for Gunners calipers, five shillings for "Rules with brass edges" and ten shillings, the most expensive, for barometer scales for altitude”.

By this time Jones was moving in the highest circles of scientific establishment, not only had he secured work from the Board of Longitude but is known to have taken commissions from the Greenwich Observatory, The Cape of Good Hope observatory, the Armagh Observatory and also from Oxford and Cambridge Universities.

Jones also had a business relationship with The East India Company suggesting that he was also involved in foreign trade on a grand scale.

In addition to his involvement with observatories, universities and The East India Company, the list of memberships to prominent societies and other appointments of work during this period are so numerous that a list is outlined below.

Royal Appointment to the Duke of Clarence and later to William IV when he acceded to the throne (circa 1817 – 1837)

Fellow of the Royal Society (1835)

Fellow of the Royal Geographical Society (1830 on its foundation)

Founder member of the Royal Astronomical Society (1820)

Member of the Society of Arts

Member and later and Associate of the Institute of Civil Engineers (1824 & 1836)

Admiralty Hydrographic Office – business appointment

East India Company – business appointment

The Board of Ordnance – business appointment

Royal Observatory at Greenwich (With Tulley) – business appointment

Board of Longitude – business appointment

Jones had a son also named Thomas (born circa 1811) and in 1831, a partnership, Thomas Jones & son was formed which traded from the Charing Cross address. Most records have this new firm trading only until 1835 and this may have been due to Thomas (the younger) attending the London Mechanics Institute in 1834 whereafter the name seems to revert back to the original and it was during this time that Jones the elder was elected a Fellow of the Royal Society. He also created a lactometer for Sir Joseph banks and an azimuth compass for Henry Kater.

In 1850, the firm moved to Rupert St and Jones is reported to have died in his shop there on the 29^th of July 1852. The business continued until 1861 at this address so must have been continued by Thomas the younger. He is buried in St James Church, Piccadlly.

As an interesting footnote to the story of Thomas Jones, there exists a record from 1827 at the Old Bailey regarding a court appearance of Robert Martin charged with breaking into Jones’s property at Charing Cross and stealing a large sum of money. The appearance has a transcript online but ultimately Martin was found guilty of the charge and sentenced to death. A sobering reminder of the strict laws which the Georgians lived under.

Given Jones’s working dates and his relationship with The Duke of Clarence, this early example of a black glass horizon can be firmly dated to between 1817 and 1830. The addition of the script, “pupil of Ramsden” on his trade card would suggest an even earlier attribution.

Circa 1820