I have likened the boulder to an old volume of the middle ages encased in a modern binding. We have looked a little into the mechanism and history of the boards; in other words, we have gone over the history of the scratched surface of the boulder, of the clays and sands around it, and of that still earlier cycle of denudation whereof the rock itself is probably a relic. Before proceeding to open the volume itself, it will be well that we clearly mark the wide interval in time between the ages represented by the surface-striation and those indicated by the interior of the boulder. When we proceed from the groovings on the outside to the plants within, we pass, to be sure, over scarcely an inch of space, but we make a leap over untold millenniums in point of time. It is as if we had laid our hands on a volume of history which had by some misfortune found its way into the nursery. The first page that catches our eye relates the battle of the Reform Bill, and, on turning the previous leaf, we find ourselves with Boadicea and her woad-coloured soldiery. Now, if one utterly ignorant of the chronology of the country were to be told that the volume related solely to one people, he would at once see from the manners and customs delineated, that the two pages referred to very different states of civilisation, and consequently to widely-separated periods. But he could give no account of how long an interval might have elapsed between the time when London had its inhabitants massacred by Boadicea, and the time when another generation of them was excited by the tardiness of King William iv. He could form no conjecture as to what events might have happened in the meanwhile. The interval might be a century or twenty centuries, wherein the city might have been burnt down fifty times. Clearly, if he wished to make himself acquainted with the intervening history, he would have to betake himself to an unmutilated volume. And just so is it with our boulder. We can easily believe, merely from looking at it as it lies on its clayey bed, that a long time must have elapsed between the time of its formation as part of a sandstone bed, and the period of its transportation and striation by an iceberg. The sand of which it is formed must have been washed down by currents, and other sediment would settle down over it. It would take some time to acquire its present hardness and solidity, while, in long subsequent times, after being broken up and well-rounded by breaker or current action, it may have lain on some old coast-line for centuries before it was finally frozen into an ice-floe, and so freighted to a distance. But the stone, with all its stories of the olden time, can tell us nothing of this intervening period. It leads us from a dreary frozen sea at once into a land of tropical luxuriance, and so, if we desire to know anything of the missing portion of the chronology, we must seek it elsewhere.