It is only in the tumuli along the coast, or in those of the Romano-British period, that iron implements are ever found; whilst in the ancient burying places of the interior of the country they are altogether wanting. Herodian says of the British pursued by Severus through the fens and marshes of the east coast, that they wore iron hoops round their middles and their necks, esteeming them as ornaments and tokens of riches, in like manner as other barbarous people then esteemed ornaments of silver and gold. Their only money, according to Caesar, consisted of pieces of brass or iron, reduced to a certain standard weight.[11] It is particularly important to observe, says M. Worsaae, that all the antiquities which have hitherto been found in the large burying places of the Iron period, in Switzerland, Bavaria, Baden, France, England, and the North, exhibit traces more or less of Roman influence.[12] The Romans themselves used weapons of bronze when they could not obtain iron in sufficient quantity, and many of the Roman weapons dug out of the ancient tumuli are of that metal. They possessed the art of tempering and hardening bronze to such a degree as to enable them to manufacture swords with it of a pretty good edge; and in those countries which they penetrated, their bronze implements gradually supplanted those which had been previously fashioned of stone. Great quantities of bronze tools have been found in different parts of England,--sometimes in heaps, as if they had been thrown away in basketfuls as things of little value. It has been conjectured that when the Romans came into Britain they found the inhabitants, especially those to the northward, in very nearly the same state as Captain Cook and other voyagers found the inhabitants of the South Sea Islands; that the Britons parted with their food and valuables for tools of inferior metal made in imitation of their stone ones; but finding themselves cheated by the Romans, as the natives of Otaheite have been cheated by Europeans, the Britons relinquished the bad tools when they became acquainted with articles made of better metal.[13] The Roman colonists were the first makers of iron in Britain on any large scale. They availed themselves of the mineral riches of the country wherever they went. Every year brings their extraordinary industrial activity more clearly to light. They not only occupied the best sites for trade, intersected the land with a complete system of well-constructed roads, studded our hills and valleys with towns, villages, and pleasure-houses, and availed themselves of our medicinal springs for purposes of baths to an extent not even exceeded at this day, but they explored our mines and quarries, and carried on the smelting and manufacture of metals in nearly all parts of the island. The heaps of mining refuse left by them in the valleys and along the hill-sides of North Derbyshire are still spoken of by the country