Possibly a more accurate measurement of time for particular regions of the world might be deduced from the introduction of bronze and iron. If the former was, as many antiquarians suppose, a local discovery in Europe, and not introduced from abroad, it can give no measurement of time whatever. In America, as the facts detailed by Dr. Wilson show, while a bronze age existed in Peru, it was the copper age in the Mississippi Valley, and the stone age elsewhere; and these conditions might have co-existed for any length of time, and could give no indication of relative dates. On the other hand, the iron introduced by European commerce spread at once over the continent, and came into use in the most remote tribes, and its introduction into America clearly marks an historical epoch. With regard to bronze in Europe, we must bear in mind that tin was to be procured only in England and Spain, and in the latter in very small quantity; the mines of Saxony do not seem to have been known till the Middle Ages. We must further consider that tin ore is a substance not metallic in appearance, and little likely to attract the attention of savages; and that, as we gather from a hint of Pliny, it was probably first observed, in the West at least, as stream tin, in the Spanish gold washings. Lastly, when we place in connection with these considerations the fact that in the earliest times of which we have certain knowledge, the tin trade of Spain and England was monopolized by the Phoenicians, there seems to be a strong probability that the extension of the trade of this nation to the western Mediterranean really inaugurated the bronze period. The only valid argument against this is the fact that moulds and other indications of native bronze casting have been found in Switzerland, Denmark, and elsewhere; but these show nothing more than that the natives could recast bronze articles, just as the American Indians can forge fish-hooks and knives out of nails and iron hoops. Other considerations might be adduced in proof of this view, but our limits will not permit us to refer to them. The important questions still remain: When was this trade commenced, and how rapidly did it extend itself from the sea-coast across Europe? The British tin trade must have been in existence in the time of Herodotus, though his notion of the locality was not more definite than that it was in the extremity of the earth. The Phoenician settlements in the western Mediterranean must have existed as early as the time of Solomon, when "ships of Tarshish" was the general designation of seagoing ships for long voyages. How long previously these colonies existed we do not know; but considering the great scarcity and value of tin in those very ancient times, we may infer that perhaps only the Spanish, and not the British deposits were known thus early; or that the Phoenicians had only indirect access to the latter. Perhaps we may fix