Wilkinson · 1775
Iron-Mad Wilkinson and the first cylinder
On the morning of Thursday the fourth of May 1775, at the New Willey ironworks at Broseley in Shropshire, the forty-six-year-old Cumbrian iron master John Wilkinson (called by his contemporaries 'Iron-Mad' for his conviction that every artefact, vessel and structure that could be made of iron should be made of iron) delivered to the Scottish steam-engineer James Watt (then forty, working on the Lunar Society circuit out of Birmingham as the technical partner of the Birmingham toy manufacturer Matthew Boulton) the first precision-bored cast-iron steam-engine cylinder ever produced. The cylinder, fifty inches long and eighteen inches in internal diameter, had been bored on the new Wilkinson boring machine patented at Bersham the previous January (Patent No. 1063 of the twenty-seventh of January 1774, 'A New Method of Casting and Boring Iron Guns or Cannon'), which rotated the workpiece around a fixed cutting head mounted on a heavy iron bar passed through the bore: the principle, transferred from cannon-boring to engine-boring at Watt's request, produced an internal cylindrical surface true to within the thickness of an old sixpence (about one sixty-fourth of an inch) over the full fifty-inch length. The first cylinder was installed in Wilkinson's own New Willey blowing engine, the air-pump that drove the blast furnace, in the spring of 1776. The engine ran. The Watt separate-condenser steam engine, demonstrated in Glasgow in 1765 but commercially unbuildable for the decade after because no English foundry could bore a cylinder accurately enough to hold the steam pressure against piston-blowby, was at that moment a commercial proposition. The Boulton-and-Watt firm at Soho, Birmingham, took out its first commercial orders by the end of 1776. The Industrial Revolution, in the specific sense of the long century of high-pressure-steam manufacturing, dates from that cylinder.
Revolutions of the mechanical kind do not begin with an invention. They begin with the second machine, the obscure one, the unsentimental tool that makes the first machine possible. The cylinder is bored true, and a continent of factories and railways and locomotives and ironclads follows over the next hundred years, and nobody remembers the name of the foundry on the Severn that bored it.
THE WILKINSONS OF BACKBARROW
Isaac Wilkinson, a Cumberland farmer's son, walked off his father's land at Backbarrow in Furness in 1735 with a knowledge of the bloomery and a small inheritance and set himself up at the Backbarrow Iron Company in the Lake District, then at Wilson House near Lindale, then at Bersham near Wrexham in Denbighshire by 1753. He was a stocky, voluble, hard-bargaining Cumbrian Dissenter who patented a cast-iron box smoothing-iron in 1738 (the patent that put the word 'iron' on every wife's ironing-board in the English-speaking world) and a hollow-ware iron-casting process in 1758. His eldest son John was born at Clifton-on-Eden near Penrith in 1728, schooled at Adam Holme's academy at Kendal, apprenticed at the Backbarrow furnace from the age of fifteen, and by 1761, at thirty-three, had taken over the Bersham works from his retiring father and was building, with his brother William, the second-largest iron complex in England.
THE NEW WILLEY
In 1757 John had leased land at Broseley on the south bank of the Severn opposite Coalbrookdale, ground rich in coal and ironstone and adjacent to the Darby furnace where Abraham Darby had, fifty years before, first smelted iron with coke instead of charcoal. He built the New Willey furnace there in 1763 and the New Willey foundry alongside it. By 1770 New Willey was casting cannon for the Royal Navy and the East India Company; by 1773 it was the largest gun foundry in England outside the Royal Arsenal at Woolwich. The casting of a cannon is one half of the operation; the boring of the cannon, true and straight down the centre line of the casting, is the other. The boring methods of the 1770s English foundry were eighteenth-century descendants of the seventeenth-century horizontal water-driven boring mill: the cylinder was held in a sled, the cutter was advanced into the bore on a fixed reciprocating spindle, and the cutter wandered. The result, accurate enough for cannon balls that rattled in their bore on the seas, was useless for a steam-engine piston that had to seal against high-pressure steam.
THE PATENT OF JANUARY 1774
John Wilkinson's reversal of the principle is described in Patent No. 1063, lodged at the Patent Office on the twenty-seventh of January 1774. The cylinder is no longer the moving part. The cylinder is fixed, and the cutter is mounted on a heavy iron boring bar that passes the full length of the bore and is supported, crucially, at both ends rather than only at the input end. The bar itself does not flex under cutting pressure because it is held by bearings on both sides of the work, the cutting head feeds along the bar on a screw advance, and the workpiece is bored from a true central axis along its full length. Wilkinson's first machines used the same boring technique for cannon and for engine cylinders interchangeably. The patent specification names cannon; the application to engine cylinders is the second use, demonstrated within fifteen months of the patent.
MAY 1775
On the fourth of January 1775, James Watt wrote to John Wilkinson from Birmingham asking whether the new machine could bore a cylinder of eighteen inches diameter and fifty inches stroke 'truer than what has hitherto been done by your method'. Wilkinson replied on the twelfth of January, 'I can bore you any cylinder of that bore within the thickness of an old sixpence in its smallest place, if it be tolerably round in the casting, and shall warrant it'. The order was placed at the end of January. Watt at this date was on his way to bankruptcy: the Newcomen-style atmospheric engine, his original target, had been overtaken; his own separate-condenser design, patented in Scotland in 1769, had been built in three prototype machines that all leaked at the piston; the Birmingham partnership with Boulton, signed in 1775, had a six-month runway and no working engine. The Wilkinson cylinder arrived at Soho by canal-and-cart in the first week of May 1775, was inspected by Watt at the Soho works, was found to be true within the promised sixpence, and was sent straight back down to New Willey to be installed in the blowing engine that Wilkinson had built around it. Watt followed it down to commission the engine.
THE BLOWING ENGINE
The engine ran on the eighth of January 1776. The cylinder held steam at fifteen pounds per square inch above atmospheric, the piston ran without measurable blowby, the separate condenser worked at the design vacuum, and the blowing tubs at the foot of the engine drove the blast furnace at a rate that, in Wilkinson's own report to the Lunar Society dinner that month, 'doubles our output and uses a third of the coke'. Watt sat with Wilkinson on a low stool by the engine-house door and watched the great cast-iron beam of the engine rise and fall on its parallel motion linkage for two hours, and said little, and was, by Boulton's letter of the same week, in a condition his partner had not seen him in before, which was the condition of a man who has just understood that a decade of careful theoretical work has at last met, in an iron-foundry in Shropshire, the machinist who can make it real. Boulton and Watt's first commercial engine order, for the Bloomfield Colliery in Tipton, Staffordshire, was placed on the eighteenth of March 1776. Twelve commercial orders followed in the next eighteen months. By 1781 the partnership had installed forty engines in collieries, copper mines, breweries, distilleries and cotton mills. By 1800, the year Watt's patent expired and the steam engine became an unrestricted commercial product, five hundred and ninety-six Boulton-and-Watt engines were at work in Britain, every cylinder bored at Bersham or, after 1795 when the two iron masters had quarrelled, at the Boulton-and-Watt Soho foundry on a Wilkinson-pattern boring mill.
THE IRON MAN OF BRADLEY
John Wilkinson's last quarter-century pushed the iron principle to its limits and beyond. In 1779 he cast many of the structural ribs of the Iron Bridge over the Severn at Coalbrookdale with Abraham Darby III, the world's first cast-iron bridge, which still stands. In 1787 he launched the Trial, a seventy-foot lighter on the Severn near Broseley, the first iron-hulled vessel ever floated, against the unanimous prediction of the Shropshire boatmen that an iron boat would sink; the Trial worked the Severn coal trade for thirty years. In 1788 he persuaded the French government to install Watt engines pumping water at the Pont de Neuilly waterworks on the Seine, the first commercial export of British high-pressure manufacturing to continental Europe; the engines pumped Paris's water until 1850. He installed iron pews and an iron pulpit in his foundry chapel at Bradley, in Staffordshire, where he had moved his principal works in the 1790s; he had a cast-iron coffin made for himself, displayed it in his office in his last years, and was buried in it at Castle Head in Westmorland after his death at Bradley on the fourteenth of July 1808, in the eightieth year of his age. The coffin was too short and his grave-diggers, on the morning of the funeral, had to dig out the inside of the casket with a hammer and chisel to make him fit. He had wanted, in the iron register that was his life's signature, to go down into the Cumberland earth in the metal his furnace had cast. The Industrial Revolution, in the long-distance sense in which the historians now mean the word, ran on Wilkinson's cylinder, Watt's separator, and Boulton's capital; of the three the cylinder is the one that, without the boring machine of the iron-mad Cumberland farmer's son, would have stayed a Glasgow university model and would not have moved a piston in a mill or a locomotive or a ship in any of the two centuries since.