Equally surprising are the discoveries made in the old red sandstone. Large slabs of this rock have been discovered in England, in Scotland, and in the United States, on which are left, as Robinson left the impression of his foot, the undisturbed footmarks of _pre-Adamite_ animals; the ebb and flow of the tide of those distant ages; the ripple-mark showing the direction of the wind; and casts of the rainprints made by showers, long long ages ere man had taken possession of the “deep places of the earth.” “Romantic nonsense!” says a grave friend; “let us go to something practical, instead of losing ourselves in such idle speculations.” Now, you are just the person whose ear we want to catch; and to you we say, just listen to the evidence of these assertions. “The casts of rainprints below project from the under side of two layers; the one a sandy shale, and the other a sandstone presenting a warty or a blistered surface, and affording evidence of cracks formed by the shrinkage of subjacent clay on which rain had fallen. The great humidity of the climate of the coal period had been previously inferred from the nature of its vegetation, and the continuity of its forests for hundreds of miles; but it is satisfactory to have at length obtained such positive proofs of showers of rain, the drops of which resembled in their average size those which now fall from the clouds. From such data we may presume that the atmosphere of the carboniferous period corresponded in density with that now investing the globe and that different currents of air varied then as now in temperature, so as to give rise, by their mixture, to the condensation of aqueous vapour.”[66] [Illustration: CASTS OF RAIN-PRINTS. ] Again, let us hear the words of Professor Ansted. “It may appear at first sight that nothing can be more fleeting, or less likely to be handed down to future ages, among the fossils of a bed of sandstone, than the casts of the impressions of the footsteps of an animal, which by chance may have walked over that bed when it existed in the condition of loose sand forming a seashore. A little consideration, however, will show that it is in fact a very possible occurrence, as, if the wet sand should be immediately covered up with a thin coating of marl, and another layer of sand be superimposed, such an impression will be permanently preserved. In after ages, also, when the soft sands have become sandstones, and are elevated above their former level, the stones split asunder wherever a layer of different material occurs; and thus it happens that the casts of the footsteps may be preserved and exhibited, although all other traces of the former existence of the animal have been lost.”[67] [Illustration: FOOTPRINTS OF A TRYDACTYLE BIRD, AND IMPRESSION OF RAIN. (_Nat. size._) ]