The first process is melting the ore in the blast-furnace.  Here the ore, with coal and a flux of limestone, is piled in and subjected to the heat of the fires, driven by a hot blast and kept burning night and day.  The iron, as it becomes melted, flows to the bottom of the furnace, and is drawn off below in a glowing stream.  Into the top of the blast-furnaces the ore and coal are dumped, having been raised to the top by an elevator worked by a blast of air.  It is curious to notice how slowly the experience was gathered from which has re suited the ability to work iron as it is done here.  Though even at the first settlement of this country the forests of England had been so much thinned by their consumption in the form of charcoal in her iron industry as to make a demand for timber from this country a flourishing trade for the new settlers, yet it was not until 1612 that a patent was granted to Simon Sturtevant for smelting iron by the consumption of bituminous coal.  Another patent for the same invention was granted to John Ravenson the next year, and in 1619 another to Lord Dudley; yet the process did not come into general use until nearly a hundred years later.

[Illustration:  Carrying the iron balls.]

The blast for the furnace is driven by two enormous engines, each of three hundred horse-power.  The blast used here is, as we have said, a hot one, the air being heated by the consumption of the gases evolved from the material itself.  The gradual steps by which these successive modifications were introduced is an evidence of how slowly industrial processes have been perfected by the collective experience of generations, and shows us how much we of the present day owe to our predecessors.  From the earliest times, as among the native smiths of Africa to-day, the blast of a bellows has been used in working iron to increase the heat of the combustion by a more plentiful supply of oxygen.  The blast-furnace is supposed to have been first used in Belgium, and to have been introduced into England in 1558.  Next came the use of bituminous coal, urged with a blast of cold air.  But it was not until 1829 that Neilson, an Englishman, conceived the idea of heating the air of the blast, and carried it out at the Muirkirk furnaces.  In that year he obtained a patent for this process, and found that he could from the same quantity of fuel make three times as much iron.  His patent made him very rich:  in one single case of infringement he received a cheque for damages for one hundred and fifty thousand pounds.  In his method, however, he used an extra fire for heating the air of his blast.  In 1837 the idea of heating the air for the blast by the gases generated in the process was first practically introduced by M. Faber Dufour at Wasseralfingen in the kingdom of Wuertemberg.