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I offer a few words of humble advice: and, for brevity sake, I will suppose myself to be addressing a young friend.

1. Do not suppose that a satisfactory knowledge of Geology can be obtained in a short time, or by skimming over a book or

two.

2. Necessary prerequisites are a knowledge of chemistry, mineralogy, and natural history, particularly comparative anatomy, conchology, and botany, according not only to the Linnæan artificial system, but to the natural arrangement of Dr. Lindley, or some other recent and eminent botanist. A profound intimacy with any one of these branches of science is indeed a work for a man's life; but where there is such a minute acquaintance with any one, a masterly knowledge of the others is easily and delightfully acquired, provided the due appropriation be made of time and diligence. But a general knowledge of essential principles, taking care that it be ACCURATE so far as it goes, may be acquired by pains-taking in the few inestimable years which usually follow a good school education.

3. Go into the field of actual search and observation: sea-cliffs, steep ravine sides, quarries, cuttings through hills for highways, canals, rail-roads, and well-diggings, or any accessible exhibitions of the faces of rocks, The great gravelly plain of London is destitute of good localities of this kind: yet the sand-pits of Woolwich yield a very good lesson. But the West of England, Wales, and the North, are the grand academy for these studies. A person who has made himself familiar with a few good instances, will be able, with the aid of books, maps, views, and sections, to form a mental idea of others; which will be in its measure just, though of course far inferior to the impression of the actual objects. Mr. De la Beche's How to Observe, in Geology, will be found of great use.

4. Hand-specimens of rocks must be studied. There are many fine collections throughout the kingdom. I may mention Bath, Bristol, Brighton, Norwich, York, Scarborough, Leeds, Newcastle-uponTyne, Liverpool, and many other places.

5. For books, without involving the least prejudice against other valuable works, I take the liberty of recommending the following short list.

Prof. John Phillips's Guide to Geology; 12mo. 1836, and his Treatise on Geology in the seventh edition of the Encyclopedia Britannica, and published separately; Edinb. 1837. The latter work forms an excellent illustration of the preceding.

Mr. Lyell's Principles of Geology; 4 vols. 12mo. the fifth edit. 1837%. An admirable collection of facts, and which carefully sepa

rates facts from hypotheses. Mr. L. makes you acquainted with the former, without urging your assent to the latter.*

Outlines of the Geology of England and Wales; by the Rev. W. D. Conybeare, and the late Mr. W. Phillips; Vol. I. 1822. Unhappily the second volume has never been published: but I have reason to hope that Mr. Conybeare will favour the world with a new work, incorporating, condensing, and completing the volume just mentioned, which is now far behind the actual state of geological science, but it can never lose its value for local descriptions.

De la Beche's Geological Manual, 8vo. 1833. Phillips's Guide should precede this.

The same author's Tablet of the Tertiary and Secondary Rocks. Viquier and Collon's Tablet, drawn from Alex. Brongniart's Tableau des Terrains. Paris.

These two are single sheets of paper upon a synoptic plan, and comprising the essence of many volumes: and the same praise is due to the Tablet which forms the first plate in Dr. Buckland's Bridgewater Treatise ; 2 vols. 8vo. 1836. That work is of the richest interest for Palæontology, the study of organic remains; but a previous acquaintance with the mineralogical branch is absolutely necessary, and it did not belong to Dr. Buckland's design and plan to supply that.

A series of exceedingly good systematical papers on Geology and the Minerals, are in the Penny Magazine, chiefly during the year 1833; but many since. No. 51, Jan. 19, 1833, contains a little Tablet admirably drawn up, perhaps in imitation of Mr. De la Beche's. Also, in the Saturday Magazine for the present year 1837, a series has commenced of Familiar Illustrations of Geology. Two articles have appeared, viz. in Nos. 329 and 344; and they well answer to their title.

A System of Geology, with a Theory of the Earth, and an Explanation of its Connexion with the Sacred Records. By John Macculloch, M. D., F. R. S. 2 vols. 8vo. 1831. This is a work which, for illustration and amplifying comment, should be read both after, and, a second and third time, concurrently with any of the preceding, Indeed I would say, that Professor Phillips's Guide and this work would admirably constitute the initial course. Dr. Macculloch was a geologist of a very high order, though he strangely neglected the

* The Elements of Geology, published by Mr. Lyell, in 1838, is a single volume, and should be studied before, and then in collation with the Principles.

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Paleontological branch, indefatigable in the arduous toils of personal examination in the most interesting regions of Great Britain, an independent thinker, and yet a man who delighted to do homage to the government and the word of God. The work was written in 1821, and therefore some modifications and corrections will accrue, by comparing it seriatim with Mr. John Phillips's books. Yet we must confess that it has serious faults of style and manner. It ought also to receive, as a most important supplement or companion, the following posthumous work of the same author; which is indeed a little too prolix, and its arrangement might admit of much improvement, had not death put upon it the sacred seal of inviolability. Proofs and Illustrations of the Attributes of GOD, from the Facts and Laws of the Physical Universe; being the Foundation of Natural and Revealed Religion. 3 vols. 1837.

Finally, let me entreat the student to be on his guard against expecting, that a few months of light reading will make him a geologist. The study is indeed one for life; and that general acquaintance with it which a person of liberal education ought to possess, must be acquired with long-continued diligence and care to be minutely accurate, or it will be liable to fall into perpetual and most serious errors. "Those who have taken a narrow view of this great and growing branch of human knowledge, who have satisfied themselves with collecting a few fossil shells, naming a few compound rocks, and constructing a few sections and maps, may possibly be startled at the mighty circle of perpetual research in which they are unconsciously engaged." Phillips's Treatise, p. 4.

Homerton, Nov. 10, 1837.

J. P. S.

Aug. 1839. I cannot resist the transcribing of some paragraphs from an unknown writer in the Christian Observer.

"As one who-has taken great interest in Geology, though no geologist, I beg to offer a few observations upon the idea that the inferior animals were not subject to death before the fall-Perhaps, the remarks of a mere Christian observer might, so far as they are of value, be received with less suspicion than those of a professedly scientific man. I was accustomed to entertain the idea of death having passed generally upon the whole creation, at the fall of man. But, when I heard of the discoveries of geologists, I was led to examine into the foundation of this opinion. I referred to Scripture; but upon examination I found no passage which supports such a notion. Not finding it declared in Scripture, I began to consider

what reason there might be for supposing it; and I was led to the conclusion that there was none. For, (setting aside the discoveries of geologists,) which is the most difficult to believe, that the inferior animals had only a limited existence, or that they were created immortal? Immortal! From the iguanodon or mammoth, to the fluttering butterfly or invisible animacule? A notion which involves a belief of the eternal duration of the earth; unless we are to suppose a series of transmigrations from world to world, as each dissolved. -The belief that death was in the world previous to the fall of Adam, I am aware, seems at first, to a Christian mind, to destroy the idea of death as a penal consequence of sin. But this difficulty soon vanishes: for, when man saw that he was placed above the inferior animals, not merely in the possession of intellect, but in being honoured with immortality while they were subject to death, he would not only understand what was meant by the threatened consequences of sin, but surely would feel the curse as denouncing a deep degradation, to be sunk to the level of that creation over which he was made lord. 'The wages of sin' were ' death;' a curse indeed, since it made him like the beasts that perish in this world, at the same time that it could not deliver the immortal spirit from the eternal wrath of its offended Maker."—J. A. W. in Christian Obs. July, 1839; p. 405.

[B.]

Referring to Prop. XVII. page 60 and to page 61.

ON THE NUMBER OF SPECIES IN THE EARLIER

FOSSILIFEROUS ROCKS.

THE XVIIth proposition of the second lecture expresses the doctrine, which till lately was received among geologists, that the organic remains found in the earliest rocks possessing any such remains at all, are "the fewest" in proportionate numbers. But the recent herculean toils of Mr. Murchison have opened new fields of view upon this interesting subject. The proposition should be modified, and understood in accordance with this important observation of that distinguished geologist; "Another remarkable fact illustrating this point of inquiry is, that, although the older fossiliferous strata often contain vast quantities of organic remains, the number of species is much smaller than in more recent deposits." Silur. Syst. p. 583.

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It is interesting to observe the careful and cautious progress of Geology, as in other respects, so in this. Seven years before the publication of Mr. Murchison's work, Mr. De la Beche had treated this subject with his characteristic judgment and sagacity. I will cite a few paragraphs, as specimens of the penetration and anticipations of his geological mind, while the facts of the case were not as yet brought clearly to light; and with a wish also to excite my readers to peruse the whole passage. It must be premised that the German term grauwacke, now generally disused, must be understood as the same with, or including, the Silurian System.

"Although, when we regard the mass of the grauwacke rocks, we are struck with the minute proportion that organic remains bear to the whole, we must still perceive that the atmosphere was capable of supporting vegetation; and the seas of sustaining zoophytes, crinoidea, annulata, conchifera, mollusca, crustacea, and fish. What other creatures existed, we are unable, from the absence of their remains, to judge: it may however be by no means unphilosophical to conclude that vegetation did not exist alone on dry land, but that, consistently with the general harmony of nature, it afforded food to terrestrial creatures suited to the circumstances under which they were placed." [Yet no vestiges of such creatures have been found.]

-"Whatever the kind of animal life may have been which first appeared on the surface of our planet, we may be certain that it was consistent with the wisdom and design which has always prevailed throughout nature; and that each creature was peculiarly adapted to that situation designed to be occupied by it." Geological Manual; third ed. pp. 428, 429; 1833.

I hope I shall not give pain to a very kind friend whose qualifications make him one of the safest authorities, by transcribing a part of a letter with which he has favoured me. The certainty and accuracy of the remarks may be fully relied upon, and their application is extensively important.

"In the older fossiliferous rocks, animal life appears in as full a development with respect to SIZE, as in the existing analogous animals. The zoophagous cephalopods were also of gigantic growth. It does not appear that animal life, at that period, was limited with respect to NUMBER. The lowest Silurian rocks are crowded, in some localities, with organic bodies; and their absence over extensive districts is only a condition in the distribution of testacea, &c., which prevails in our seas. There are many coasts from which a reasoner, who had visited no other, might infer that marine animals are now few and small-sized; and, if he were a geologist, he might say, Life is on the decrease!" William Lonsdale, Esq. Sept. 7, 1839.