rise far, far, above the more evidently political comedies of the ingenious author. Those comic curiosities, the chorus of birds, perform their part (as far as they represent the frivolous and volatile people of Athens) with sound common sense, and a just feeling of distrust for a stranger who is stealing in among them, and whose admission they vehemently oppose until their anger is appeased by a few sophistical sentences; and then, led away by the charms of novelty and captivated by this subtle flattery, their ambition and their thirst for foreign dominion carries them away; and then, again, when peace is concluded, they receive with hymns of praise their new tyrant (who is to gain all the advantages of their hard-earned treaty) and glorify the instrument whose dupe they have been, and are, and will continue to be, until some newer and more tempting demagogue dethrone him, and step into his vacant place. Who can doubt the portraitalas, for the painter's skill. We have not space to follow out the very accurate investigations of the Professor; but strongly recommend the perusal of this work to all our readers, who take sufficient interest in the plays of Aristophanes to be far from satisfied with this our short compendium. Like most of his school, the Professor has too often descended to verbal coincidences, and, led away by the novelty of his subject and the success of his theory, has been tempted to ride his hobby rather too fast. "In laying the translation of this essay before the public (says Mr. Hamilton), the translator confines himself to the expression of his own earnest conviction, that Professor Süvern has fully and completely succeeded in proving the proposition he has advanced; and he feels confident, that though some minor points may be objected to, this conviction will be felt by all who will take the trouble to read the essay, and to try the truth of its contents by a frequent reference to the play itself and to the authorities quoted by the writer."

ART. III.-The Silurian System, &c. By RODERICK IMPEY MURCHISON, F.R.S., F.L.Š., &c. &c. In Two Parts. London: Murray. 1839.

2. Report of the Geology of Cornwall, Devon, and West Somerset. By HENRY T. DE LA BECHE, F.R.S., &c. Published by Order of the Lords Commissioners of Her Majesty's Treasury. London: Longman. 1839.

THE History of Geology is, in many respects, very much unlike the history of any other science, depending on the observation of phenomena, and belonging to the class denominated "Induc

tive:"-Existing only, for centuries, in the crude speculations of cosmogonists, the real facts, upon which all reasoning must be based, were either unknown or absolutely neglected; and, so far as any rational and scientific object is concerned, the incidental remarks of Herodotus and Ovid may be considered quite as valuable as those "theories of the earth," published at a period so late as the seventeenth century, in which the invention of an hypothesis was the great and sole merit of the theoriser. It must, indeed, be acknowledged, that the first dawn of Geology as a science, was the study of fossils (i. e. of the remains of organized bodies found embedded in various strata) commenced in Italy about the year 1520, and followed up, chiefly in that country, by descriptions and figures of the most remarkable discoveries, made public at various intervals, during the remainder of that century. It was thus that facts were accumulated and recorded, and the was opened for the reception of a highly-interesting and important doctrine, viz., that the various beds of which the earth's surface is composed are characterized, and may be identified, by certain groups of fossils and particular forms of animal life. Before, however, the importance of this generalization had been felt, much had been effected, by the mineralogists and Geological theorists of the German school, and the labours of Werner had seemed to throw so much light on the mineral structure of rocks, that the importance of fossils became, for a time, under-rated, and a retrograde movement took place, retarding the progress of real scientific Geology. The effect of this retardation was long felt in the wordy and angry discussions of the supporters of two theories concerning the origin of rocks, which are commonly spoken of as the igneous and aqueous theories, because the supporters of the one-the Plutonists of that day-called in the aid of subterraneous heat and the action of fire; while the Neptunists, on the other hand, accounted for all phenomena on the supposition that every appearance was the result of deposition from water.

By the exertions of Dr. Hutton, aided by the active researches of other hard-working Geologists, those unfounded theories which had attracted attention and discussion for their ingenuity rather than their intrinsic importance, became gradually neglected, and a new order of things, a stricter enquiry into facts, and a series of well-attested observations, became looked upon as indispensable qualifications for all who pretended to a knowledge of Geology. The errors and dogmas of the schoolmen were replaced by more accurate information and rational deductions, and Geologists became willing to allow that their theories ought to depend on facts, instead of being satisfied with suppositions

and assertions. For these reasons, owing also, perhaps, partly to the institution of a society "with a view to record and multiply observations," and partly to an improved and more staid and philosophical feeling among those who occupied themselves in the investigation of natural phenomena, there began to be separated from a confused mass of contradictory hypotheses the framework of a science, definite in its objects, clear in its statements, surpassingly wonderful in the results to which it leads and the facts it unfolds, and allied to other sciences, assisting them, and assisted by them, enlarging the bounds of human knowledge, and next, perhaps, to astronomy, the most ennobling to the human intellect.

As a science, then, Geology, after a long sleep of ages, has within a few years started into active existence, and made efforts to expand itself and fill the space in the great treasure-house of human knowledge which must belong to it. In our own country, the amount of actual information obtained was far greater, more useful and universally applicable, than could possibly have been anticipated; and, owing to peculiar circumstances, and the early progress made in secondary Geology by the venerable Dr. Smith, it has so happened, that England has served as an index-map to Europe, offering to our notice within a small space, almost all the varieties of strata elsewhere spread over a large extent of country. From the chalk downwards, English names and English types have become European; and, in many cases, the barbarous local terms for particular subsoils, such as lias, cornbrash, and others, have become current among all Geologists.

Judging from the works before us, this honour our country is not likely soon to be deprived of; and we may expect to read of Silurian formations of Norway, and the Devonian rocks of other parts of Europe, as we do of the Kimmeridge clay or Oxford clay in the Jura, and the mountain limestone of Germany.

For the benefit, however, of those of our readers who have not made themselves acquainted with the daily additions to the stock of knowledge that render the pursuit of Geology so peculiarly fascinating, we proceed to give, in a few words, some account of what has been going on for the last few years. This we shall do in such a way as to communicate as far as possible a notion of the value of the services which Mr. Murchison has rendered to science. He has elaborately worked out the detail of a district, interesting in a degree scarcely credible to the uninitiated; a district which presents as a claim to attention, besides its intrinsic importance, the additional charm of entire novelty.

It is very rarely that there comes before us a scientific work like this, so peculiarly interesting and authentic in itself, and so admirable both for its picturesque illustrations and for the extreme delicacy and accuracy of the numerous scientific engravings. We feel, indeed, that in order to do it justice, we must depart from the beaten track of reviewers, and, neglecting for once the destructive propensity, be contented to admire and wonder.

Up to the year 1830, the fossiliferous strata formed by aqueous deposit were commonly divided into tertiary, secondary, and transition; the latter term sometimes interchanging with grauwacke in Germany, and signifying an indefinite and not very easily understood group, whose fossils, when there were any, were supposed identifiable with those of the carboniferous series; and, as the name imports, indicating an intermediate condition between aqueous and igneous rocks.

These transition rocks were all referred to the same Geological period, or at least no definite line of demarcation had been discovered, and several bands of limestone which had been observed, and cursorily examined, and which passed under the general name of "transition limestones," were without much examination presumed to belong to the fossiliferous deposits of the carboniferous series.

At the time, therefore, when Mr. Murchison commenced his labours, "no one (as he observes) was aware of the existence below the old red sandstone (a group subordinate to the mountain limestone) of a regular series of deposits containing peculiar organic remains."-Sil. Sys. p. 4. It should not, however, be forgotten, that before this time Professor Sedgwick had prepared himself for the solution of this and other most difficult Geological problems of the kind, by his examination of the Cumberland slates; and after spending several years upon this great and difficult task, he, with our author, commenced the Geological examination of the whole principality of Wales. By a mutual arrangement, entered into, we believe, in the summer of 1831, they agreed to undertake the laborious work separately, Professor Sedgwick going into North Wales, because there the greatest difficulties were expected, and the most accurate and practical knowledge of the older* and altered rocks was required; while to Mr. Murchison fell the south-eastern district, which was supposed to be more nearly analogous to known secondary deposits. In this division of labour, therefore, the

* The Geological reader will be aware that, from the position of the strata in England (all tilted towards the East), the older formations appear necessarily in the West, and make their appearance one after another as we advance towards the Western coast.

more easy, fertile, and interesting portion fell to the lot of Mr. Murchison, whose reference to his fellow-labourer we are happy to have an opportunity of quoting, as it forms a just tribute to the exertions of one whose name will long live as among the greatest of British Geologists:

"In speaking of the labours of my friend (observes Mr. Murchison), I may truly say that he not only shed an entirely new light on the crystalline arrangement, or slaty cleavage, of the North Welch mountains, but also overcame what, to most men, would have proved insurmountable difficulties, in determining the order and relations of these very ancient strata and scenes of vast dislocation. He further made several traverses across the region in which I was employed, and sanctioning the arrangement I had adopted, he not only gave me confidence in its accuracy, but enhanced the value of my work by enabling me to unite it with his own, and thus have our joint exertions led to a general view of the sequence of the older fossiliferous deposits."Murchison, p. 6.

We have been thus particular in calling attention to the labours of Professor Sedgwick, because we do not think that in the world he has yet received credit for the many years of most arduous labour which he has spent in examining the structure of North Wales, bringing to bear, as he did upon that examination, a greater amount of qualifications than any other English or foreign Geologist could boast of possessing. We pass on now to other circumstances connected with the Silurian System.

The first general view of the discovery-for so it must be called-of a series of well-defined strata forming a natural group, and occurring below the old red sandstone, was given at the meeting of the British Association, held at York, in 1831. It was not till two years afterwards, at the close of the summer of 1833, that a synopsis was published of its various formations; and during the succeeding six years almost the whole attention of our author was given to the developement of the subject and its collateral branches.

We believe it is now the intention of Mr. Murchison to follow out his researches on the continent, to reduce the incomprehensible grauwacke of the Germans into order; to show, if possible, the contemporanity of various continental strata with the Silurian rocks of our own country; and, perhaps, also the passage of the carboniferous system into the Silurian, by a series of fossiliferous deposits, identical in geological position with the coarse conglomerate called "old red sandstone," and the shales of Devonshire and Cornwall.

Whatever may be the result of these enquiries and examinations--and, with so persevering and patient an examiner as