Besides his speculations on railways worked by horse and steam power, Mr. Edgeworth--unconscious of the early experiments of Stevins and Mackworth--made many attempts to apply the power of the wind with the same object. It is stated in his "Memoirs" that he devoted himself to locomotive traction by various methods for a period of about forty years, during which he made above a hundred working models, in a great variety of forms; and though none of his schemes were attended with practical success, he adds that he gained far more in amusement than he lost by his unsuccessful labors. "The only mortification that affected me," he says, "was my discovery, many years after I had taken out my patent [for the sailing-carriage], that the rudiments of my whole scheme were mentioned in an obscure memoir of the French Academy." The sailing-wagon scheme, as revived by Mr. Edgeworth, was doubtless of a highly ingenious character, though it was not practicable. One of his expedients was a portable railway, of a kind somewhat similar to that since revived by Mr. Boydell. Many experiments were tried with the new wagons on Hare Hatch Common, but they were attended with so much danger when the wind blew strong--the vehicles seeming to fly rather than roll along the ground--that farther experiments were abandoned, and Mr. Edgeworth himself at length came to the conclusion that a power so uncertain as that of the wind could never be relied upon for the safe conduct of ordinary traffic. His thoughts finally settled on steam as the only practicable power for this purpose; but, though his enthusiasm in the cause of improved transit of persons and of goods remained unabated, he was now too far advanced in life to prosecute his investigations in that direction. When an old man of seventy he wrote to James Watt (7th August, 1813): "I have always thought that steam would become the universal lord, and that we should in time scorn post-horses. An iron railroad would be a cheaper thing than a road on the common construction." Four years later he died, and left the problem, which he had nearly all his life been trying ineffectually to solve, to be worked out by younger men. Dr. Darwin had long before preceded him into the silent land. Down to his death in 1802, Edgeworth had kept up a continuous correspondence with him on his favorite topic; but it does not appear that Darwin ever revived his project of the "fiery chariot." He was satisfied to prophesy its eventual success in the lines which are perhaps more generally known than any he has written--for, though Horace Walpole declared that he could "read the Botanic Garden over and over again forever," the poetry of Darwin is now all but forgotten. The following was his prophecy, published in 1791, before any practical locomotive or steam-boat had been invented: