Subsequently, Trevithick applied his high-pressure engine to rock-boring and breaking, and dredging. He laid out a system of dredging the Thames River, planned a tunnel under the Thames, invented a high-pressure steam threshing engine in 1812, constructed iron tanks and buoys, and modeled an iron ship. He was one of the first to conceive the practical use of steam in agriculture, declaring that the use of the steam engine for this purpose would "double the population of the kingdom and make our markets the cheapest in the world." In 1814, Trevithick became interested in a plan to work the silver mines of Peru by Cornish methods, and nine of his high-pressure engines were sent to South America in charge of Henry Vivian and other engineers. He himself followed in 1816, and remained in that country ten years, making and losing several fortunes during that time. Finally, in a revolution, the mining plants were destroyed, and he was forced to leave the country, penniless. For a time he was prospecting in Costa Rica, where he planned a railroad across the Isthmus from the Atlantic to the Pacific. In 1827 he returned to England, still a poor man, and settling in Dartford, Kent, devoted himself to new inventions, unsuccessfully endeavoring to secure the help of the government in his work. His later years were spent in poverty, and when he died, the expense of his burial was borne by his fellow-workmen of Dartford. Undoubtedly, Trevithick was one of the foremost English engineers of his day, a period that was rich with strong men of distinction in his profession. By many he has been considered as having contributed more even than James Watt to the development of the steam engine and its broader adaptation to practical uses. In his early years he was restrained in putting his ideas and experiments to practical test by the restrictions of Watt's patents. Finally when that difficulty was removed he at once took a leading position in his profession. Especially in the development of the high pressure engine he is entitled to at least as much credit as any man of his day. His genius was fully recognized in his generation and his impoverished old age was the result of financial reverses in business operations and not from the lack of substantial rewards for his inventive achievements. DAVID GORDON