Other mills soon followed. The first to have iron beams as well as stanchions seems to be the Benyons, Marshall & Bage flax spinning mill in St Michael’s Street, Shrewsbury. This was built in 1796-7 from the designs of Charles Bage (1752-1822) a friend and correspondent of Strutt. The much-publicized Salford Twist Company’s cotton mill at Salford of 1799-1801, designed and built by Boulton & Watt of steam-engine fame—they knew Bage’s mill since they had installed his steam-engine—was according to present evidence the second[152] to be erected with a complete internal skeleton of iron. By 1800, then, a system of fire-resistant construction using cast-iron stanchions and cast-iron beams, carrying what are sometimes called ‘jack-arches’ of brick, had been established in the world of English mill-building. By 1850 such construction was in use in Britain for almost all high-grade building. The system was significantly modified, however, after about 1845 by the substitution of rolled—that is wrought—iron beams, as proposed by Sir William Fairbairn (1789-1874),[153] since cast-iron ones had proved dangerously brittle. It is not necessary here to do more than sketch out the steps by which the new iron skeleton structure became generally accepted. In 1802-11 James Wyatt introduced it in the Castellated New Palace that he built at Kew for George III, an edifice of which little is otherwise known since it was demolished in 1827-8. In line with this curious conjunction of technical and stylistic innovation, already noted in Schinkel’s somewhat later cast-iron Gothic monument of 1819-20 in Berlin, is Porden’s profuse use of iron for the Gothic traceries and balustrades at Eaton Hall[154] in Cheshire in 1804-12, as also by Hopper in the even more ornate Gothic Conservatory at Carlton House in London in 1811-12 (Plate 60B).