The production of coal and iron trebled during the period 1880-1900, amounting in 1900 to 6,600,000 tons, and 463,000 tons respectively.
The worlds output of oil was trebled between 1885 and 1895, and quadrupled between 1885 and 1900.
In the raising of the standard of farming to an English level the volume of the world's crop would be trebled, another fact which Sir William Crookes seems to have overlooked.
A great amount of doubled and trebled yarn is now sold, though it does not appear that recent expansions have added much to doubling spindles, and considerable developments continue in the use of dyed and mercerized yarns.
The trade of Belgium has more than trebled as regards both imports and exports since 1870.