Trevithick had prevailed upon his brother-in-law Henry Harvey's good nature to try out the new closed cycle steam engine at the Harvey & Co foundry
in Hayle. An experimental engine was completed, one with a 510mm diameter cylinder. Trials had taken place in November 1829, showing that it had a duty of 36.2 million. However, work had not proceeded as well as Trevithick anticipated and this had led to a quarrel with Harvey.
Under pressure to uphold his reputation for innovation, Trevithick travelled to London, arriving on 14th February 1830. He spent 10 days in central London before moving to Lauderdale House in Highgate — the school where the Montealegre Fernández brothers boarded — because of ill health, which may have meant asthma, bronchitis, stress or even a nervous breakdown.
In Cornwall, Trevithick had been developing what he called 'hot-house apparatus' for the heating of Davies Gilbert's London house. The pipework was made at Hayle. He intended to use heated steam in the pipes but by March 1830 was suggesting that boiling water might be better. He described a portable stove — essentially a boiler on wheels — that was in effect an early form of storage heater.
His patent (No. 6083) Apparatus for heating apartments was granted on 21st February 1831. The portable stoves proved popular and were produced in ornate styles, which people left on view rather than hiding them behind curtains as Trevithick had envisaged.
However, he had not forgotten the closed cycle engine. He realised that engines for steam ships had to be as small and powerful as possible, since space on board for engines and fuel was limited. In June and July 1830 he applied to the Admiralty for loan of a suitable vessel in which to try his engine, even involving Simon Goodrich of the Navy Board, but without success.
The closed cycle engine combined a multi-flue boiler, a superheater, a heat exchanger and a condenser, all in one unit. His patent (No. 6082) of 21st February 1831 described the the five main aspects of the design: placing the boiler inside the condenser to allow steam to condense without water injection; enclosing the condenser within an air or water vessel; the surface condenser; returning condensed steam from the condenser back to the boiler; and heating the fire with a forced draught of hot air heated by the condenser water.
On 27th January 1832, Gilbert and fellow Cornish MP Edward William Wynne Pendarves (1775-1853) sent a testimonial to the Admiralty recommending Trevithick's closed cycle engine. Another engineer, George Mills (1796-1859), wrote to the Admiralty on 10th January and to the Royal Society on 10th January and 2nd March 1832 outlining its benefits. The Admiralty remained unconvinced.
Someone who did appreciate Trevithick's ideas was John Hall (1764-1836), a millwright and entrepreneur who owned a paper mill and an engineering works at Dartford (established 1785) and a gunpowder mill at Faversham, all in Kent. Trevithick joined Hall at Dartford sometime in 1832 and published what would turn out to be his final patent (No. 6308), Steam engine; application of steam power to navigation and locomotion, on 22nd September that year.
The patent covered four areas: the superheater for which steam forced through a pipe between the boiler and the cylinder absorbs additional heat and expands; the cylinder placed in the flue or chimney to ensure that it is hotter than the steam used in it (which expands the steam further); the jet propulsion of vessels using the recoil force produced from a jet of water with a velocity at least double the required speed of the vessel being propelled; and the application of a boiler combined with a superheater to a locomotive engine.
Trevithick was also working on proposals for a ship impeller and he designed a reaction turbine. This may have been similar to his 1815 recoil engine, which used jets of steam rather than water. Trials of jet propulsion were carried out at a cost of more than £1,200, but it was another idea ahead of its time and not taken any further. However, Hall and his firm (later J. & E. Hall Ltd) went on to develop more conventional marine steam engines from 1835.
The 1830s was a decade of change for British politics, with growing impetus for the reform of the electoral system after the death of George IV on 26th June 1830. The first Reform Bill was introduced to Parliament in March 1831, and in May Trevithick began designing a column to commemorate the event. The bill gained royal assent on 4th June 1832 (Scotland and Ireland passed separate Reform Bills in the same year) in its third incarnation.
Trevithick's Reform Column was intended to be a gilded conical cast iron tower, 305m high (St Paul's Cathedral is 111m) and 30.5m in diameter at its base, with an internal passenger lift powered by atmospheric pressure. He sent a copy of his design to William IV and received an acknowledgement on 1st March 1833, but by then his health was failing and the scheme was never built — though it excited considerable public attention.
Trevithick was lodging at the Bull Inn on Dartford High Street while working with Hall. On 22nd April 1833 he died there, after a week's illness, probably from pneumonia. He had just passed his 62nd birthday. The news of his death wasn't communicated directly to his wife in Cornwall, and none of his family attended the funeral.
On the day of his death, the innkeeper Rowley Edward Potter (c.1805-76) wrote to Trevithick's nephew and executor, John Tyack Jnr, son of Elizabeth Trevithick and John Tyack Snr. The following day, William Gittins, proprietor of Lauderdale House, wrote to Henry Harvey. Tyack Jnr replied on 24th April that his uncle's will should be handled by his London solicitor, though it seems unlikely that there would have been any monetary legacy for Trevithick's family.
The funeral was conducted by the Reverend Francis Bazett Grant (1795-1872), vicar of Dartford, at the chapel of St Edmund, King and Martyr, on 26th April. Trevithick was buried in the upper graveyard
there (now a parkland called St Edmund's Pleasance).
Though it has been reported that he had a pauper's funeral, later research suggests that Trevithick's gold watch — brought back from South America — was sold to cover most of the expenses, with Hall (and perhaps his colleagues at the engineering works) paying the balance. Workers from Hall's company were pallbearers and vigil-keepers at the graveside, protecting the engineer's body from graverobbers. A grandson of one of the pallbearers remembered that there was a headstone but this has disappeared. The exact location of the grave is unknown.
Trevithick's death passed almost unnoticed among the engineering fraternity of the day, perhaps because he had slipped from public attention during his long years in South America. He died before any of his children married but he did found a strong healthy family whose descendents have spread across the world. Jane remained at the White Hart Hotel as its landlady until 1836 and died on 21st March 1868 aged 95.
Only his eldest child, Richard, did not marry and though there are few details of the lives of his daughters Anne and Elizabeth, his three other sons John, Francis and Frederick had a total of 25 children, only four of whom died in childhood and 14 lived for more than 70 years. Francis and two of Trevithick's grandsons would become noted railway engineers.
portrait of Richard Trevithick Institution of Civil Engineers