The Trent and Mersey canal is 93 miles long, with 75 locks, and rises at the Harecastle tunnel to a height of 326 feet above the Mersey. It is 20 feet broad at the top, 16 feet at the bottom, and 4 feet 6 inches deep, and it cost £300,000.[101] It is carried on aqueducts over the Dove, Trent and Dane, and there are five tunnels. It was pushed on by Brindley with great energy till his death, and completed at last in 1777 by Hugh Henshall, his son-in-law, together with a branch to the Severn from Great Haywood. Brindley died at Turnhurst in Wolstanton on Sept. 27, 1772. In 1786 we read that freight for general goods on the canal was 1¼d. per ton per mile, or less than one-seventh what freight cost before the canal was cut.[102] At the same time the £200 shares in the canal were standing at £600-£700 apiece.[103] It was carrying over 1,350,000 tons of goods and minerals a year in 1849, when it was bought out by the railway company for £1,170,000. A fresh development of the potting industry took place even while this canal was building. China clay and china stone were discovered by Cookworthy in Cornwall. This was in 1768, and Cookworthy took out a patent for the use of these materials. He never succeeded in producing porcelain on a commercial scale, and in 1773 sold his patent rights to Richard Champion.[104] Mr Champion was one of the chief supporters in Bristol of Edmund Burke, member for that city, and conceived in 1775 the idea of getting with his aid a Bill passed through Parliament to extend the patent which he had bought from Cookworthy for a further seven years. But china clay and china stone had during these last few years been proved of value not only for making china, but also as a constituent of the clay body used for making the cream-coloured earthenware of Staffordshire. It had been imported and used by Wedgwood, Turner of Lane End, the Warburtons and others, and an extension of Cookworthy’s patent, giving to Champion of Bristol the monopoly for seven more years of the right to use this material, whether for making china or earthenware, was naturally resisted by the earth potters of Staffordshire. In this opposition Wedgwood and Turner took a leading part; and their action has been criticized by many who thought they saw in Champion the struggling inventor penalized by pushing capitalists. From another and as reasonable a point of view Champion was a speculator who tried to use political influence to increase the value of a monopoly that he had bought on a different basis. As Mr Burton says, “It certainly seems that the fullest justice was done when Champion was allowed an extension of the patent for the use of china clay and china stone _in porcelain_, the only substance ever produced by Cookworthy or Champion, and the other potters were allowed to use the same materials in earthenware bodies.”[105] [Illustration: WILLIAM TURNER, MASTER POTTER Fl.: 1780]