In some countries, in the granular limestone of New Jersey for instance, or the ripidolite of North Carolina, the granite of Siberia, or the dolomites of Switzerland, we find sapphire, or more properly corundum, of undecided colors, of inferior transparency or even of opacity; but it is very rare that a specimen is found of sufficient purity for ornamentation. The most transparent and perfect of these sapphires are generally impaired by cleavage planes which traverse the stone in several directions, preventing refraction of light, and often so marked as to appear like flaws. This circumstance indicates that the forces that deposited corundum and the fine sapphires were certainly different in character, or that the conditions in which they were exerted were not the same. For in Burmah, Pegu, India, or Ceylon, and wherever the perfect sapphires are found, they have one common matrix, and that is the peculiar ferruginous conglomerate. This conglomerate is recognized as a recent formation; and how came these gems, which are believed to be as old as creation itself, to be found among it? This formation is not only recent, but it is actually taking place all over the world at the present day, and examples may be found in almost every country. We find in many places the peculiar strata of sand, gravel, and masses of stone in proper position to change into conglomerate, which requires the action of water highly charged with iron and lime or silica. Darwin found these stony layers in process of forming on the beaches of the Cape de Verde Islands, and in vain attempted to knock out a bolt of iron which had been cast ashore from some wreck not long before, and had in a short space of time become firmly fixed in the conglomerate. We may observe the same process taking place to-day on the coast of Cornwall, and among the _débris_ of the ledges of the Abrolhos Islands. In dredging rivers large masses of solid conglomerate are often brought to light. The Thames has furnished many examples; and not many years ago a cannon-ball embedded in a crystalline calcareous rock was taken from the bed of the Mediterranean not far from the mouth of the Rhone. Fresh water laden with _débris_ of vegetable matter also possesses the same cementing action as sea water, and an excellent example is seen in the allios now forming in the Landes of southern France. This allios is also a conglomerate, which has formed and is now forming at the depth of about three feet below the surface. Here the conglomerate of sand, pebbles, and angular fragments of rock is firmly cemented together by the rain-water, which filters down from the surface of the earth laden with vegetable matter. The cascalho in which the diamond is found is of similar character, and has a similar origin, for we likewise find there traces of vegetable _débris_, and the diamond itself contains germs of fungi and vegetable fibres of higher organizations.