It was not to be expected that Arkwright would enjoy undisturbed so valuable a monopoly as that which he had created, and many persons infringed his patents, in the belief that he was not the real owner of the inventions which he claimed. An attempt was made in 1772 to set aside his first patent for the water-frame; but this failed, and he retained the enjoyment of that patent unquestioned till the expiration of the fourteen years. To preserve his second patent, for the carding, drawing, and roving machines, he brought several actions against master-spinners, one of which, against Colonel Mordaunt, was tried in 1781, and a verdict was obtained for the defendant, setting aside the patent. Arkwright for some time did not contest this decision. But in 1785, he made another attempt to establish his second patent before a court of law; and in the first instance obtained a verdict in his own favour, but on the cause being reheard, the patent was finally declared invalid. Notwithstanding this defeat, Arkwright rapidly acquired a very large fortune, through the magnitude of his concerns, and his industry, penetration, and skill in business. On the dissolution of his partnership with the Messrs. Strutt about 1783, the extensive works at Cromford fell to his share. In 1786, he was High Sheriff of Derbyshire, and was knighted, on occasion of presenting an address to the King. We find no other record worth notice of the last years of his life. He died, August 3, 1792, in his sixtieth year.