It may now be received as an established fact, that the manufactures of this period consist entirely of bronze and not of brass--that is, of an alloy of copper and tin, and not of copper and zinc; but also including other metals, and especially a proportion of lead, in some examples exceeding the quantity of tin present. Even among the Romans we have abundant evidence that the alloy of copper and zinc was rarely used, although it is now known to be both more economical, and easier to work into a variety of forms. Mr. Worsaae, after remarking on the resemblance observable among the weapons, implements, and ornaments of bronze found in various countries, both in the north and south of Europe, adds,--"They have all been cast in moulds, and the metal is of the same composition--nine-tenths copper, and one-tenth tin. From this there would be farther reason to suppose that they all originated with one people."[283] This country, as has been already shewn, he elsewhere supposes may be England. From a careful examination and comparison of the antiquities themselves, however, the Danish archæologist is led to the conclusion that the bronze objects were manufactured in the various countries of Europe, where they are now found, and that only the metal was imported from some common centre. The same idea appears at one period to have been adopted by the Rev. Dr. Robinson, an Irish archæologist still more distinguished for his devotion to astronomical science than for his intelligent elucidation of antiquarian investigations; but the results of more extended observation, communicated by him to the Royal Irish Academy in 1848, shew that he was ultimately led to a different conclusion. Minute examination of the bronzes themselves will be found to throw fully as much doubt on the probability of a common origin for the mixed metal, as for the weapons into which it has been fashioned. The difference even in colour and texture is very great, and in some cases still only imperfectly accounted for. Many of the bronze weapons found both in Scotland and Ireland, are of a bright yellow colour, like brass, or rather resembling gilded metal; it does not tarnish, and, on analysis, is found to contain no zinc. Others are more of a copper colour, also little liable to tarnish or corrode; while a third quality, if polished, rapidly resumes a dark and nearly black colour, and is frequently found covered with verd antique. To the first of these the term _Celtic brass_ is often applied, though it is in common use for all the varieties of primitive bronze. Analysis of these relics by no means bears out the idea of any uniform system of combination of the pure metals, or of their being derived from a single source in the form of bronze. The variations in the proportionate admixture of the metals were indeed necessarily confined within a limited range, especially in the manufacture of weapons. It did not require any mutual intercourse