The town of Dudley was already a centre of the iron manufacture, though chiefly of small wares, such as nails, horse-shoes, keys, locks, and common agricultural tools; and it was estimated that there were about 20,000 smiths and workers in iron of various kinds living within a circuit of ten miles of Dudley Castle. But, as in the southern counties, the production of iron had suffered great diminution from the want of fuel in the district, though formerly a mighty woodland country; and many important branches of the local trade were brought almost to a stand-still. Yet there was an extraordinary abundance of coal to be met with in the neighbourhood--coal in some places lying in seams ten feet thick--ironstone four feet thick immediately under the coal, with limestone conveniently adjacent to both. The conjunction seemed almost providential--"as if," observes Dud, "God had decreed the time when and how these smiths should be supplied, and this island also, with iron, and most especially that this cole and ironstone should give the first and just occasion for the invention of smelting iron with pit-cole;" though, as we have already seen, all attempts heretofore made with that object had practically failed. Dud was a special favourite of the Earl his father, who encouraged his speculations with reference to the improvement of the iron manufacture, and gave him an education calculated to enable him to turn his excellent practical abilities to account. He was studying at Baliol College, Oxford, in the year 1619, when the Earl sent for him to take charge of an iron furnace and two forges in the chase of Pensnet in Worcestershire. He was no sooner installed manager of the works, than, feeling hampered by the want of wood for fuel, his attention was directed to the employment of pit-coal as a substitute. He altered his furnace accordingly, so as to adapt it to the new process, and the result of the first trial was such as to induce him to persevere. It is nowhere stated in Dud Dudley's Treatise what was the precise nature of the method adopted by him; but it is most probable that, in endeavouring to substitute coal for wood as fuel, he would subject the coal to a process similar to that of charcoal-burning. The result would be what is called Coke; and as Dudley informs us that he followed up his first experiment with a second blast, by means of which he was enabled to produce good marketable iron, the presumption is that his success was also due to an improvement of the blast which he contrived for the purpose of keeping up the active combustion of the fuel. Though the quantity produced by the new process was comparatively small--not more than three tons a week from each furnace--Dudley anticipated that greater experience would enable him to increase the quantity; and at all events he had succeeded in proving the practicability of smelting iron with fuel made from pit-coal, which so many before him had tried in vain.