seemingly transitional forms of pottery makes it probable that it was through such stages that the art grew up into the more perfect form in which we usually find it, and in which it has come to be clearly understood that clay, alone or with some mixture of sand or such matters to prevent cracking, is capable of being used without any extraneous support.
Such is the evidence by means of which I have attempted to trace the progress of mankind in three important arts, whose early history lies for the most part out of the range of direct record. Its examination brings into view a gradual improvement in methods of producing fire; the supplanting of a rude means of boiling food by a higher one; and a progress from the vessels of gourds, bark, or shell of the lower races to the pottery and metal of the higher. On the whole, progress in these useful arts appears to be the rule, and whether its steps be slow or rapid, a step once made does not seem often to be retraced.
