The effect on the iron industry itself of the improvements in manufacture was prodigious. The 17,350 tons of iron which were alone produced in 1740 came from 59 furnaces, {191}using charcoal only. In 1788 the number of furnaces had increased to 85, and the output to 68,300 tons, of which 55,200 tons had been produced by coke, and only 13,100 tons by charcoal. In 1796, when the charcoal process had been almost entirely given up, the number of furnaces was 121 (in England and Wales 104; in Scotland 17), and the production was 124,879 tons. In this same year Pitt proposed to put a tax on coal, and the following year he sought to impose one on pig-iron; but a taxing of raw material was not to be tolerated, and he had to abandon each project. Adding to these details corresponding figures for other years in the Canal Era, we get the following table:-- Iron Furnaces and Production in England, Wales and Scotland. Year. Number of furnaces. Production (tons). 1740 59 17,350 1788 85 68,300 1796 121 124,879 1802 168 170,000 1806 227 250,000 1820 260 400,000 1825 374 581,367 This great increase in the output of iron meant, also, a considerable expansion in the engineering trades of the country in general, in the hardware trades of Birmingham, in the cutlery trade of Sheffield, and in many other trades besides. It led to the opening up of new centres of activity and industry in addition to a greater aggregation of workers in centres already established; while the combined effect on the coal industry itself of all these developments is well shown by the following figures, giving the output of coal in the United Kingdom, for the years mentioned, as estimated by the Commissioners of 1871:-- YEAR. TONS. 1700 2,612,000 1750 4,773,828 1770 6,205,400 1790 7,618,728 1795 10,080,300