Page:Popular Science Monthly Volume 31.djvu/804

This page has been validated.
784
THE POPULAR SCIENCE MONTHLY,

average product per man of the furnaces of Great Britain, which for 1870 was estimated at 173 tons, is reported to have been 194 tons in 1880, and 261 tons in 1884.

Third. The substitution of steel for iron has resulted in a notable diminution of the consumption of iron for the attainment of a given result, or, in other words, more work is attainable from a less weight of material. Sir Lowthian Bell, in his testimony before the Royal British Commission, stated that a ship of 1,700 tons requires 17 per cent less in weight of pig-iron, in being built of steel rather than of iron, and is capable of doing 7 per cent more work.

Again, the quantity of pig-iron requisite for keeping a railroad in repair will depend greatly upon the state in which iron enters into construction; rails of steel, for example, having a far greater durability than rails of iron.[1]

A further example of recent economic disturbance consequent upon changes in the manufacture of iron—characterized by the Secretary of the British Iron Trade Association, in his report for 1886, as "one of the most remarkable of modern times"—is to be found in the rapid disuse of the system invented about one hundred years ago by Henry Cort for converting pig-iron into malleable iron by the so-called process of "puddling." Twenty years ago the use of this process was almost universal, to-day it is almost a thing that has past; and the loss of British capital invested in puddling-furnaces which have been abandoned in the ten years from 1875 to 1885, is estimated to have approximated £4,667,000, or $23,333,000, involving in Great Britain alone a displacement, or transfer of workmen to other branches of industry during the same period of about 39,000.

Copper.—This metal touched the lowest price on record in 1886, Lake Superior copper in New York falling from 25 cents per pound

  1. Opinions, as yet, vary greatly as to the comparative durability of iron and steel rails. In the testimony given before the British Royal Commission, Mr. I. T. Smith, manager of the Barrow Steel Company, gave it as his opinion that the life of a steel rail is three times that of an iron rail, adding, "My reason for saying so is, that I know that upon the London and Northwestern Railroad, where steel rails have been now in use more than twenty years, they consider it so."
    Sir Lowthian Bell also, in testifying before the commission, on the effect on the iron-trade of Great Britain from the expected longer duration of steel rails, says: "Assuming iron rails to last twelve, and steel rails twenty-four years, instead of the railways now in existence in the United Kingdom requiring 465,648 tons annually for repairs, 232,824 tons will suffice for the purpose. Although this only involves the saving of a comparatively small weight of pig-iron, it means less work for remelting and for our rolling-mills, say to the extent of 4,000 to 5,000 tons per week." The difference in duration of iron and steel rails is not, however, in itself a complete measure of the amount of pig-iron required for renewals. This arises from the fact that an iron rail splits up and becomes useless long before the actual wear, as measured by the diminution of weight, renders it unsafe, which often happens when the loss of weight does not exceed 4 per cent of the original weight. Steel rails, on the other hand, go on losing weight until they are from 10 to 20 per cent lighter than when they were laid down, before becoming unsafe.