IRON 933 



decrease in the manufacture in others ; so complete indeed vras the failure of all the 

 experiments made to substitute pit-coal for charcoal, that all attempts were abandoned 

 till the early part of the next century, when pit-coal was first used (1713) by Mr. 

 Abraham Darby in his furnace at Colebrook Dale ; and in the 44th volume of the 

 Philosophical Transactions, published in 1747 it is stated, that 'Mr. Ford, from iron 

 and coal, both got in the same Dale (Colebrook), makes iron brittle or tough as he 

 pleases, there being cannon thus cast so soft, as to bear turning like soft iron.' Not- 

 withstanding, however, the establishment of the fact that iron ore could be smelted, 

 and iron manufactured with pit-coal, and although great efforts were made, by 

 increasing the column of blast by the substitution of steam-power for that of 

 horses and human labour, there appears to have been a steady and progressive 

 diminution in the quantity of iron produced in this country ; and recourse was had to 

 foreign markets, particularly to those of Sweden and Kussia, for the necessary and 

 increasing demand. Thus, the imports of iron between the years 1711 and 1776 were 

 as follow : 



Tons 



1711 to 1718 . . .... . . 15,642 



1729 1735 . 25,501 



1750 1755 .-,./.-.,* '..-< . . 34,072 



1761 1766 .'.-.. j,v, > . 48,980 



In 1740 there were only 59 blast-furnaces in work in England and Wales, the total 

 make of which amounted to not more than 17,350 tons, being an average of 294 tons 

 per annum for each furnace, a quantity very little exceeding that sometimes made in 

 a single week in some of the furnaces in Wales at the present day. 



The earliest contrivance for throwing a powerful and constant blast into the furnace 

 was a forcing pump, worked by a water-wheel or by a steam-engine ; and it appears 

 that the first cylinders, at least of any magnitude, were erected at the celebrated 

 Carron Iron Works in the year 1760 by Mr. John Smeaton. These cylinders were 

 four feet six inches in diameter, exactly fitted with a piston, moved up and down by 

 means of a water-wheel ; in the bottom of the cylinder was a large valve, like that 

 of a bellows, which rose as the piston was lifted up, and thus admitted the air into the 

 cavity of the cylinder below. Immediately above the bottom was a tube which went 

 to the furnace, and as it proceeded from the cylinder, was furnished with a valve 

 opening outwards. Thus when the piston was drawn up, the valve in the bottom 

 rose and admitted the air that way into the cylinder, while the lateral valve shut, and 

 prevented any air from getting into it through the pipe. When the piston was thrust 

 down, the valve in the bottom closed, while the air, being compressed in the cavity of 

 the cylinder, was violently forced out through the lateral tube into the furnace. There 

 were four of these large cylinders applied to blow the furnace, and so contrived, that 

 the stroke of the pistons, being made alternately, produced an almost uninterrupted 

 blast. A large column of air, of triple or quadruple density, was thus obtained, and 

 effects equivalent to these great improvements followed. The same furnace that 

 formerly yielded ten and twelve tons weekly, now sometimes produced forty tons in 

 the same period, and on the average in one year 1,500 tons of metal (Scrivenor) ; and 

 such was the impulse given to the trade by this unexpected success of a powerful blast 

 with pit-coal, that in 1788 the manufacture of pig-iron in England, Wales and Scotland, 

 amounted to 68,300 tons, being an increase of 50,950 tons on the quantity manufactured 

 previous to the introduction of pit-coal. 



A new era in the history of the iron manufacture may be considered to have been 

 established in 1788-90, by the introduction of the double power-engine of James 

 Watt, the regular and increased effects of which powerful machine was soon felt 

 in most of the iron districts ; the proprietors of furnaces greatly increased their make, 

 and fresh capital was embarked in the trade ; in the short period of eight years the 

 manufacture of pig-iron was nearly double, being in the year 1796 (according to the 

 return sent to the Chairman of the Committee of the House of Commons, on the sub- 

 ject of the coal trade, when Mr. Pitt had in contemplation to add to the revenue by 

 a tax upon coal at the pit-mouth) 125,079 tons from 121 furnaces 104 English and 

 Welsh, and 17 Scotch ; the English and Welsh furnaces producing an average of 1,048 

 tons each per annum, and the Scotch furnaces 946 tons. In 1806, the number of 

 furnaces in blast in Great Britain was 173, and the make 258,206 tons of pig-iron, 

 being an increase in ten years of 133,127 tons per annum; of these 162 were coke- 

 furnaces, the average produce of each of which had risen to 1,546 tons. In this year 

 great excitement existed in the iron trade, in consequence of the proposal of Lord 

 Henry Petty to levy, as a war-tax, a duty of 405. per ton on pig-iron ; he introduced 

 a bill into the House of Commons having this object, and succeeded in carrying it, 



