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6 Coming down to more modern times, Eccard in 1750, and Goguet in 1758, mention the three latter ages in plain terms; the same idea runs through Borlase's History of Cornwall; and Sir Richard Colt Hoare also alludes to "instruments of stone before the use of metals was known," and expresses the opinion that instruments of iron "denote a much later period" than those of bronze.

To the Northern archæologists, however—especially to C. J. Thomsen, the founder of the Museum at Copenhagen, and to Professor Nilsson—must be ascribed the merit of having raised these suggestions to the rank of a scientific classification.

The art of obtaining metal when once discovered offered no great diflficulty. Dr Percy indeed tells us that "nothing more easy can be conceived." In various parts of the world metal is still obtained by very simple methods. Dr Gowland quotes examples from Japan and several parts of Africa, India, etc. Among the hill tribes of the Ghats in India "the furnace is first filled nearly half full of charcoal, and upon this, fire is put, after which it is filled to the top with charcoal. The blast is then applied. When the charcoal sinks at the top of the furnace, alternate charges of ore and charcoal are supplied until the proper charge of ore has been introduced, after which the blast is increased and maintained till the close of the operation. The greater part of the slag remains in the furnace and is taken out along with the iron. In from four to six hours a charge is completed, when, the front of the furnace being removed, a small mass of malleable iron, slag, and unburnt charcoal is drawn out." The iron is then hammered into a bar.

Even at the present day in Ceylon the bloom or mass of iron is taken out of the furnace with long tongs made