We all know that whatever we do to do well we must do earnestly. It is not a thing taken in hand now and then, by fits and starts, that ever reaches the perfection necessary to give it prominence and raise it above things ordinary.

A London society, simply because it is a London society, is not therefore composed of more talent than a provincial society; nor, if it be, is that talent necessarily more effectually applied than it would be by any other society whatever. But as the metropolis is the centre and focus of the English ordinary population, so we think its learned societies ought to be the centres and foci of all the provincial societies. By this we do not advocate that the London societies should at all control the actions of any of the other societies; but we can not but think that the greatest good would arise from a combination of all the provincial Geological Societies and Field Clubs with that which ought to be their natural head—the London Geologists' Association. If the Geological Society itself could be made the great centre of attraction, so much the better; but the exclusive nature of that institution, and the antique system upon which its laws and regulations are founded, seem to prohibit, at least, for the present, any hope of its giving that invaluable help which it has all the materials in its hands for doing.

The rooks composing the earth's crust contain a history and represent time—a history of changes numerous, varied, and important: changes in the distribution of land and water; in the thermal conditions of the world; and in the character of the organic tribes which have successively peopled it. The time required for these mutations must have been vast beyond human comprehension, requiring, for its expression, units of a higher order than years or centuries. In the existing state of our knowledge it is impossible to convert geological into astronomical time: it is at present, and perhaps always will be, beyond our power to determine how many rotations on its axis, or how many revolutions round the sun the earth made between any two recognised and well-marked events in its geological history. Nevertheless it is possible, and eminently convenient, to break up geological time into great periods: it must not be supposed, however, that such periods are necessarily equal in chronological, organic, or lithological value; or separated from one another by broadly marked lines of demarcation; or that either their commencements or terminations in different and widely separated districts were strictly synchronous.

One of the terms in the chronological series of the geologist is known as the Devonian, that which preceeded it the Silurian, and the succeeding one the Carboniferous period; and these, with some others of less importance, belong to the Palæozoic or ancient-life epoch, or group of periods.