Immediately on his return home, Trevithick memorialized the government for some remuneration adequate to the great benefit which the country had derived from his invention of the high-pressure steam-engine, and his introduction of the cylindrical boiler. The petition was prepared in December, 1827, and was cheerfully signed by the leading mine-owners and engineers in Cornwall; but there their efforts on his behalf ended. He took out two more patents--one in 1831, for a new method of heating apartments, and another in 1832, for improvements in the steam-engine, and the application of steam-power to navigation and locomotion; but neither of them seems to have proved of any service to him. His new improvement in the steam-engine was neither more nor less than the invention of an apparatus similar to that which has quite recently come into use for employing superheated steam as a means of working the engine more effectively and economically. The patent also included a method of propelling ships by ejecting water through a tube with great force and speed in a direction opposite to the course of the vessel, a method since reinvented in many forms, though not yet successfully introduced in practice. Strange to say, though Trevithick had been so intimately connected with the practical introduction of the Locomotive, he seems to have taken but little interest in its introduction upon railways, but confined himself to advocating its employment on common roads as its most useful application.[18] Though in many things he was before his age, here he was unquestionably behind it. But Trevithick was now an old man; his constitution was broken, and his energy worked out. Younger men were in the field, less ingenious and speculative, but more practical and energetic; and in the blaze of their fame the Cornish engineer was forgotten. During the last year of his life Trevithick resided at Dartford, in Kent. He had induced the Messrs. Hall, the engineers of that place, to give him an opportunity of testing the value of his last invention--that of a vessel driven by the ejection of water through a tube--and he went there to superintend the construction of the necessary engine and apparatus. The vessel was duly fitted up, and several experiments were made with it in the adjoining creek, but it did not realize a speed of more than four miles an hour. Trevithick, being of opinion that the engine-power was insufficient, proceeded to have a new engine constructed, to the boiler of which, within the furnace, numerous tubes were attached, round which the fire played. So much steam was raised by this arrangement that the piston "blew;" but still the result of the experiments was unsatisfactory. While laboring at these inventions, and planning new arrangements never to be carried out, the engineer was seized by the illness of which he died, on the 22d of April, 1833, in the 62d year of his age.