and can predict to some extent its future results? Can we practically apply our knowledge to rendering the materials of the Earth more readily useful, or more easily managed, than without such knowledge? It would be too bold to reply fully in the affirmative to all these questions as to Geology and its standing as a science; and it would be false to say "no" to any of them.

We have before us manuals or guide-books, either newly written or re-edited, which, with others already before the public, will help us in coming to some conclusions,-besides a book, such as it is, avowedly for the philosopher, who wishes to form a perfect idea of the subject in all its bearings, and a pamphlet (weak and rambling) pointing to some of the facts and notions of late brought forward by geologists.

The materials of the Earth, as far as they are presented to observation, have been studied by chemist and mineralogist; the wants of the one in striving to get a complete notion of the characters of crystalline and other minerals often urging the other to new discoveries; but both have still to labour in ascertaining the exact natures and properties of the gases, fluids, and solids of the outer portion of the globe-of the interior, shut in from sight and touch, little can be known. The application of chemistry (the knowledge of the relationship of particles of matter) to geology is seldom shown in elementary books. Jukes's 'Student's Manual of Geology' (1862) uses it sparingly as introductory to the study of "rocks" (as geologists term the hard or soft mineral masses forming the solid earth): but it is little chemical knowledge that can be got at second-hand; and a real basis of practical experience is required. Knowing something of chemistry, the student can handle minerals; and Dana will guide him well by his succinct notices of the "constituent minerals of rocks," in Part II. of his Manual,' or better still by his Mineralogy,' and Manual of Mineralogy,' both in many editions. There are good French and German guides too,-Naumann, Beudant, and others. In Britain, Nicol's Mineralogy' represents that of Naumann; we have also the good old English Phillips' 'Mineralogy,' redressed by Brooke and Miller; and there are works by Greg, Mitchell, and others.

So much for minerals,—but minerals compose "rocks" that must be described and understood. Here English literature is deficient as to special works; but good chapters on the subject may be found in Dana's Manual' and Mineralogy,' and in Jukes's Student's

Manual.' Abroad, the French, Germans, and others, give us books on "rocks;" and Naumann's 'Lehrbuch der Geognosie' is a quarry in itself for students to work in. In some good manuals, as those by Lyell and Phillips, the mineralogical characters of " rocks" are described in connection with their modes of formation and places of occurrence.

The arrangement of mineral masses in the Earth's outer portion, such as we can get at and see, or such as we have fair cause to guess at, owing to their evidently continuing downwards, out of sight, but under conditions that we can understand, is a subject of which all geological manuals must treat as fully as they can,-both as to the stratified and unstratified, the slaty, crystalline, and other conditions of rock-masses,-and as to the more or less definite successional arrangement of certain strata, veins, and irregular masses of earthy and stony substances. Jukes's Student's Manual' is pre-eminent

for its treatment of the conditions and relations of rock-beds-or of stratification; and Phillips and Naumann are also careful to give much sound information on this division of geological study, termed by the latter "Geotechtonik."

The important character given to most bedded rocks by the presence of petrified remains of animals and plants, calling for accurate discrimination of these fossils in different strata, necessarily requires zoological and botanical knowledge, which, thus applied to the study of fossilized beings, gives rise to the paleontological portions of geological manuals, and to some special volumes by English and foreign paleontologists, such as Mantell's Medals of Creation,' Owen's 'Palæontology,' and Pictet's and Bronn's still more comprehensive works; whilst the shells of Mollusca, so frequent in the fossil state, have their classification and their generic characters concisely described and clearly illustrated in S. P. Woodward's Manual of the Mollusca.' Fossils and their imbedding strata are usually treated of together in manuals of geology; and they thus from the subjectmatter of A. d'Orbigny's Cours Elémentaire de la Géologie et de la Paléontologie Stratigraphiques.' Dana's 'Manual' is largely furnished (to the extent of nearly half its bulk) with well-illustrated "Stratigraphical Paleontology," chiefly applied to North America. In Jukes's 'Student's Manual' more than a third of its pages, with many new well-chosen figures, are devoted to this subject. Phillips and Lyell's Manuals,' and Mantell's Wonders,' are equally well provided on this point; and various elementary books, by Ansted, Page, and others, British and foreign, are also in different degrees,

highly illustrative of fossils arranged according to strata. Indeed the same cuts of fossils and strata stare us in the face again and again as we open many of the popular expositions of geology.

For a knowledge of the relations borne by fossils to strata, by strata one to another, and to different rocky masses, and by all these to the earth as a whole, we can still go to manuals of geology as safe teachers; for, in this, as in other branches of the science, their writers have collected and digested much that has been observed and calculated pertinent to the subject; the authors themselves often having largely contributed to the stock of original information. This knowledge of the relationship of mineral matters comprehends an acquaintance with the causes of the formation both of fossils and of stratified and unstratified rock-masses. Therefore, as Nature teaches the competent observer, by her daily operations, how these phenomena are brought about, the manuals are careful to put before us the agencies by which animals and plants become fossilized, by being imbedded under various circumstances in mud and sand, brought by water, in some form or other, from high ground to the water-level, and there arranged in beds,-or by being amassed as peat-bogs in lakes-or as coral-reefs, shell-banks, and microzoal ooze in deep, clear ocean-water; and how strata are otherwise formed by blown sand, and by ashes and lava erupted from volcanos; whilst some of the melted matter in volcanos fills cracks and forms dykes, or hardens deep down as crystalline rock; and water, dribbling through all these matters, forms crystalline salts and metallic minerals in cavities and fissures. All this is well put by Dana, in Part IV. of his "Manual" before us, under the head of " Dynamical Geology." By Naumann and Jukes the making of "rocks" is treated of in connection with the description of them; whilst Phillips and Lyell keep the two subjects-characters and origin of “rocks"—more distinctly separate. Indeed the modern changes of the earth's surface by means of water and fire, and the formation of fossil-bearing deposits in rivers, lakes, and seas, form the chief matter of the highly prized "Principles of Geology," by the latter of these veteran philosophers; whilst the changes, in character and distribution, of the present animal and vegetable inhabitants of the globe are studied, in the same great work, as illustrative of modifications and replacements shown by the different groups of fossils to have occurred in former times.

To Ansted's "Elementary Course of Geology, Mineralogy, and

Physical Geography," the student may have recourse also for a digest of the facts connected with atmospheric, aqueous, and igneous actions on the earth of to-day, and their relation to the geographical and meteorological conditions of the surface, or, as Dana terms it, to "Physiographical Geology' ('Manual,' Part I.).

We must not forget, however, that Constant Prévost and H. T. De la Beche were among the earliest who reduced to system useful observations on the effects of wind and weather, of snow, ice, and rain, of the river, lake, and sea, the volcano and the earthquake, and brought them clearly in relation with the results of similar operations in past time, making them explain the stony records of the earth; thus carrying out the views of many earlier geologists, one of whom, Deluc, had already defined the science (to which he gave the name “Geology”) as including "not only a knowledge of the phenomena exhibited at the earth's surface, but also the investigation of the physical causes from which the actual state of the globe has proceeded." For English compilers, De la Beche's works have been a mine of wealth as regards geological Dynamics; and when geologists treat of the theoretical aspects of the science, they too often forget to acknowledge that therein also he either advanced, or brought within their reach, the ideas that they offer to the public.

Having correct views of the natural agencies affecting the Earth's surface, of their methods and results--of the continual disintegration and restitution of that surface-of the manifold effects of heat and water acting on mineral matter of a thousand shapes-of the parts played by animals and plants in modifying sea-beds and other portions of the earth, can the geologist yet say that he knows enough of chemical, electrical, mechanical, and vital processes and products to be able to interpret those indications of the Earth's earlier conditions and inhabitants that are presented to his notice in its stony structure? Can he trace backward, step by step, the faint and devious foot-prints of old Time? Can he define the primeval ocean-eaten lands, and their successive forms, out of which our varied continents and islands have arrived at their present forms? Can he tell one by one the volcanos, above and below the sea, that have in turn laboured effectually in melting the rocks beneath, and in heaping new matter up above; the fire-fields spreading like a fever-rash from land to land in all ages, staying for a while like a dread hectic, or passing on with tremours to burst in other regions with burning pustules, until Time, the curer, renews Earth's face with verdure? Can the long past

tribes of life be known to the Geologist, all in their ranks and numCan he apportion to them their lakes and seas, their upland and their valley homes? Can he sort out the contemporary groups without an error, assign them to their stages in the successive sea-beds, and make the fossil shell, or bone, or leaf, serve as the medal in the hand of the antiquary, or as the sculptured column at the foot of the well-read traveller in a forgotten land? Has he not too often to make up history from crumbling bones and layers of ashes rather than from the equivalents of the lettered coin and classic capital? In fact, can he trace effects and their causes from to-day backwards into the unreckoned past, over all the Earth, at all depths beneath the sea, the greensward, and the mountain-ridge? Can he connect all the operations of nature on this terraqueous globe into one great plan of sequence and association, coming out of some simple, it may be dim-lighted, original?

This is asking too much of the Geologist of to-day. However far advanced he may be beyond the founders of his science, he is not yet master of it. The recognition of the natural plan by which changes are unceasingly produced on the earth, adding to its fixed records, illustrating former changes, and enabling man to comprehend how works for mining, engineering, and agriculture may best be done, was a great result of the intellect, observant, comprehensive, and cautious, of the first real geologists. But, blinded by the vanity of half-knowledge in local workers, and fettered by the bigoted ignorance of others, Geology had to grope her way until, for England, at least, De la Beche, Lyell, and Phillips, scattering the misty speculations of books, systematized the phenomena of active and passive change, gave well-considered systems of strata, as determined by their contemporaries and themselves, and threw the collective knowledge into hypothesis and theory-into supposition for convenience' sake, and into more or less complete philosophic systems of cause and effect in connection with the great system of creation. Thus they illustrated, if they did not lay down, the principles on which the Geologist, tracing out the cause in the effect, either by observation, experiment, or analogy, found that a general plan of the Earth's structure was before him, that a general sketch of the Earth's history could be given, and that the order and mutual relations of strata and other rock-masses, as well as the place of certain useful minerals among them, could be recognized and taken advantage of for practical purposes.