The upper vessel, A, is inserted in the lower vessel B, by means of a ground tubular neck, which is rendered air-tight. At the end of this neck is a mass of zinc, z, immersed in water charged with sulphuric acid. The reaction of the water on the acid and the metal, produces a disengagement of hydrogen, which at first finding ro means cf escape, drives the water of Fig. 228. R Lower Greensand of the chalk formation, you come to a group of rocks cailed the oolite (pronounced 60-0-lite). The name of this sytem of rocks is derived from two Greek words-dov, oo-on, an egg, and Aiece, lithos, a stone-eggy-stone, or the egg-rock. The rock is called oolite on the ground that, where it was first especially examined, the stone consisted of diminu tive egg-like grains, much resembling the roe of a fish; and hence called, sometimes, the roe-stone. Each of these egglike grains has within it a microscopical fragment of sand, or worn coral, as a nucleus, around which, as the grain was rolled along in a stream of limy water, layers of calcareous matter gathered around it, and when it became too heavy for the water, it sank into the calcareous bottom, and formed what is now called oolite. The oolite group of rocks is sometimes called the Jurassic System, from the fact that they form the great mass of the Jura mountains, which separate the north-east of France from Switzerland. But when the system is called Jurassic, it comprehends the lias, on which the oolites rest. The oolitic system is generally divided into three great groups, called the Upper, the Middle, and the Lower. F. Forest Marble. G. Great Oolite, or Bath Stone. H. Stonesfield Slate. 1. Fullers' Earth. J. Interior Oolite, or Cheltenham Stone. All the oolitic strata develop themselves as you travel from London to Bath. On that route you find that the different clays and limestones have given rise to high escarpments and limestone beds, whether they be of chalk or oolite, form hills and mountains, which terminate abruptly towards the west, while from underneath them the clays are seen to rise. This is represented in fig. 6. the vessel B into the vessel A, until the zine is no longer iminersed in it; the cork of the upper vessel is employed laterally so as to allow the air to escape as the water ascends. A short copper tube, H, fixed on the side of the vessel B, carries a small conical piece, E, having an orifice, above which, in a capsule, D, is placed spongy platinum. Now, as soon as the stop-cock which closes the copper tube is opened, the hydro-wide valleys. Between each valley covered with clay, the gen is disengaged and burns in contact with the platinum. Great care must be taken not to present the platinum to the current of hydrogen, until this gas has expelled all the air which is in the vessel B, otherwise there would be a strong detonation arising from the combination of the oxygen and hydrogen contained in the vessel B. The heat produced by the changes in the state of a body have been already investigated under the heads of "Solidification" and "Liquefaction," in a former Lesson; and as to the heat developed by electricity, this must form part of our separate chapter in Physics, under that title. LESSONS IN GEOLOGY.-No. LIV. THE CLASSIFICATION OF ROCKS. THE OOLITES. IMMEDIATELY underneath the Purbeck beds of the Wealden, or, where there is no Wealden, immediately underneath the I. LITHOLOGICAL CHARACTER OF THE OOLITE. A. PORTLAND STONE.-The Portland stone is well known as supplying a valuable building material, which is especially adapted to ornamental architecture. Large quarries of it have been opened at Purbeck, in Dorsetshire, and at Fonthill and Tisbury, in Wiltshire. This bed has, in reality, three seams or layers. 1. The uppermost, which is of a yellowish colour, is called by the workmen the cap, and is burned for lime. 2. The middle, which supplies the very best building stone. 3. The lower, which contains the casts of shells, and is, on that account, not so fit for being tooled. B. KIMMERIDGE CLAY.-Kimmeridge is the name of a village in a small bay of the isle of Purbeck, where this clay is best developed. The clay is slaty in texture, blue and yellowish in colour, and consists of calcareous or limy matter abounding with vegetable and animal remains. Some beds of this clay are very much like peat, and so A. Lon lon Clay. ». Chalk, c. Gault. D. Upper Oolite. E. Kimmeridge Clay. F. Middle Oolite. . Oxford Clay. 1. Lower Colite. 1. Lias. bituminous or pitchy as to be used for fuel, and it is, on that [5. Sandstone, containing clays and seams of coal, and ironaccount, called, in some places, Kimmeridge coal. It burns stone with vegetable remains. 6. A bed of limestone and dully, with a yellow smoky flame, having a strong smell of sand, corresponding with the interior oolite of the south of pitch. Some suppose that this mass of bituminous matter England. results from the decomposition of vegetables; but others, on account of the bed abounding with marine shells, suppose it to be of animal origin. In some places the beds contain the sulphate of lime and iron pyrites (pronounced pee-ry-tes). This remarkable circumstance is accounted for by the supposition that the iron pyrites, in decomposing, produces sulphuric acid, or oil of vitriol, which, by uniting with the calcareous or limy matter in the clay, forms the sulphate of lime. In England these two oolitic beds, A and B, are found only in the southern counties of Wiltshire and Dorsetshire, where they form beds of different thickness, averaging from 70 to 700 feet. II. THE MIDDLE COLITE. The strata of the middle oolite consists of gritty imperfect limestone, forming a freestone-very perishable for building materials, as may be seen in several of the older buildings of Oxford. It is full of broken or comminuted shells, and consists, in different places, of from one-tenth to one-third of sand. The middle oolite is divided into three beds. 1. The ebral rag. 2. The calcareous grit. 3. The Oxford ciny, of calcareous matter. At Brora, also, on the east coast of Sutherlandshire, in the north of Scotland, are found shelly limestones with alterations of sands and shales, iron-stones with remains of plants, ferruginous or irony limestone with fossil wood and shells, and sandstones and shales with thin beds of coal. E. CORNBRASH.-The cornhrash is an imperfect limestone, rough and rubbly, of a brown and earthy appearance. This rock generally separates into thin layers. It is chiefly burned for lime; but occasionally, when masses of considerable thickness of it are found, it is used tor building, as about Malmes bury, in Wiltshire. It has immediately underneath it a bed of blue clay, which is sometimes of very great thickness, and rests on a siliceous grit-stone. F. FOREST MARBLE.-The forest marble consists of brownish beds of argillaceous or clayey limestone, full of marine fossils. The more solid beds in this division furnish a stone of sufficient compactness to receive a polish, and is hence called a marble. The thin beds afford coarse roofing tiles and rough flagstones, much used in West Wiltshire and in Somerset. The different twelve inches in thickness. lagets are separated by thin seams of clay, from one inch to The whole rests on a deep bed of marly deposit called the Bradford clay, full of organic remains. G. GREAT OOLITE.-The great oolite consists of calcareous heds, having different degrees of compactness and consistency. The softer beds are perfectly oolitie, or consisting of egg-shaped particles; but the harder and more compact beds have less of that roe-like appearance. C. THE CORAL RAG-The coral tag is a kind of rubbly limestone, formed chiefly by the branching corals called madrepores. This stone or rag is called "corsi. because its bed, consists of masses of petrifed corals, warh appear to retain the very position in which they grew at the bottom of the sea. These masses of coral rock are somtimes fitteen feet thick. It is used only for burning lime and mending roads. The best of these beds supply that beautiful building mateBetween the coral rag and the Oxford clay, is found a bed rial called the BATH STONE, which, on account of its softness of calcareous or my grit, consisting chiefly of siliceous or when taketi from the quarry, is capable of every variety of flinty sand of a yellowish colour, having in it about one-third artistical embellishment. St. Paul's Cathedral, in London, is These two beds form a rock of from 100 to 150 feet in thick-The hills around Bath are composed of it, and the city of Bath built of this stone from a quarry at Burford, in Oxfordshire. ness; but at Whiteham-hill, in Berkshire, it attains an eleva- is built with it. When in the quarry, the Bath stone is soft and yellowish, but by exposure it becomes hard and white. H. STONESFIELD SLATE.-The Stonesfield slate is a bed of limestone of only six feet in thickness, and it is but very slightly oolitic. It was first known at Stonesfield, near Woodstock, in Oxfordshire, and subsequently at Hinton, near Bath, Colly weston, in Northamptonshire, and the Cleveland Hills, in Yorkshire. The bed, though thin and limited in extent, is remarkable for the abundance and the variety of its fossils, both vegetable and animal. tion of 576 feet. D. THE OXFORD CLAY.-The Oxford clay is very tenacious, dark blue in colour, but brown on the surface. It forms a bed of great thickness, and contains masses of Septaria, or cement-stone. In some places these Septaria are called Turtlestone; in others, Melbury marble, from a district of that name in Dorsetshire. In some places the Oxford clay is found combined with bituminous matter, and forms an inflammable shale, like that of the Kimmeridge clay, à circumstance which has led to several abortive attempts at discovering coal. In the lower parts of this clay are remarkable beds of limestone, which is formed almost entirely of one mass of fossil shells. This singular bed has been called Kelloway rock, on account of its being so well developed at Kelloway-bridge, near Chippenham, in Wiltshire. The Oxford clay, like the Kimmeridge, contains iron pyrites and sulphate of lime; and also, very probably, free sulphur, for when a mass of the clay is burned, it emits a very offensive smell. The well of Melksham Spa, in Wiltshire, which is a sulphureous chaly beate, is sunk in this clayey stratum. The same is the case with the springs at Cumor, in Berkshire; Kingscliff, in Northamptonshire; and Stansfield, in Lincoln shire. The lower oulites form a very extensive group, consisting of hard rocks with intervening beds of sands and clays. The group of lower volites is divided into the following beds: 1. Cornbrash. 2. Forest marble. 3. Great oolite. 4. Stonesfield slate. 5. Fuilers' earth. 6. Inferior oolite. In the northern parts of Great Britain the beds differ in lithological character from those of the southern parts. In Yorkshire, as developed on the eastern coast, the division this: 1. Cornbrash. 2. Sandstones and clays. 3. Shales, with thin layers of coal. 4. Calcareous sand and shelly limestone. The quarries at Stonesfield exhibit different fossil beds of buff coloured oolitic limestones, called Pendle, each seam about two feet in thickness; separated by a bed of loose sand called Race of the same thickness. Imbedded in this look like cakes of limestone, from six inches to two feet limestone are concretions called Whimstone, or Potlids. These into parallel' flakes, and as they separate, their surfaces often in diameter, and often blue in the centre. This cake splits expose impressions of shells. The masses of the bed called then, when struck hard on the edge, they also freely split into Pendle are allowed to lie exposed to a winter's frosts, and flakes sufficiently thin to be used for roofing. At Collyweston, the Stonesfield strata contain some fossil ferns of a species common to the beds of the Yorkshire oolites, where, on the eastern coast, rocks of the bolitic age put on every aspect of a real coal field, and where thin stains of coal have been actually worked, as in Brora in Sutherlandshire, for many years. 1. FULLERS' EARTH.-Under the Stonesfield limestone is a deep bed of clay. In many places this bed of clay is much like Fullers' earth; but at Odd-down, near Bath, the bed is really formed of that earth. It contains partial beds of a rubbly stone of a blue colour. This bed is entirely wanting in the oolites of Yorkshire and Sutherlandshire. J. INFERIOR OOLITE.-The inferior oolite, not to be con founded with the phrase "lower oolites," is a calcareous rock, coarse and gritty. It is distinguished from the "great oolite" by being much coloured with the red oxide of iron and by being more mixed with siliceous sand. In its midland and northern course, in England, it consists of siliceous and ferruginous sandstone, supplying sometimes hard and gritty flagstones, but of very little use in building. In the southwestern counties it is more calcareous, and more compact, furnishing good building materials, which, though of darker colour than the Bath stone, is scarcely inferior to it. It is sometimes called Cheltenham stone. Fine quarries of it have been opened in Dundry Hill, near Bristol, and at Doulting, near Shepton Mallet. II. THE ORGANIC REMAINS OF THE OOLITE. The oolitic series of rocks presents a good field for the study of Paleontology, for each subdivision in the system is distinguished by its peculiar fossils. Our next illustration represents some of the shells and other organic remains found in this group. has no corals, but it has fossil Ammonites, No. 12, and Belemnites, No. 4, in great abundance. 4. The Great Oolite, near Bath, contains various corais, especially the Eunomia rudiata. In the face of the quarry, a single individual of this species of coral sometimes forms a mass of several feet in diameter. That individual coral must have taken many centuries to grow to that size. In this bed are also found different species of Encrinites or stone lilies, represented by No. 15. These must have had a firm ground at the bottom of the sea, where their roots must have remained undisturbed for many centuries. No. 15 represents an Encrinite, called Encrinites moniliformis, as it grew on the surface of the Great Oolite. In the tall figure, the arms of the coral are closed, but to the right, a young one has its arms expanded. 5. The Stonesfield slate abounds in the fossil remains of 1. The Portland stone abounds with organic remains, especially of marine shells, such as the Trigonia, No. 8, and ammonites, like No. 10 and No. 12, sometimes two or three feet in diameter. Corals are rare in Portland stone, but in a quarry of it at Tisbury, in Wiltshire, one species of coral is found very plentiful. 2. The Kimmeridge clay abounds in organic remains, especially of Saurians, or lizards, and tortoises and fish. In Bavaria, this clay has furnished many fossils of a species of flying lizard, or the Pterodactyl, mentioned in our last lesson. It abounds in shells of the Nautilus, No. 13, Ammonite, No. 12, and Belemnite, No. 4. But the most characteristic shells are those of the Ostræa Deltoidea, and, in France, the Gryphaa Kirgula, a shell like No. 3. 3. The Coral Rag is so called because it abounds with the remains of corals, belonging chiefly to the family of the Astraa, No. 11, the Caryophyllia, and the Agaricia. It has also furnished many fossil remains of Saurian animals. In the calciferous grit connected with the Coral Rag, fossil wood, drifted out to sea, is often found, The Oxford clay, underlying it, tortoises, of two or three varieties of the crab and lobster tribes, the backbones of fishes, marine shells, bones of birds, parts of insects, and especially the wings of a beetle. What has rendered this slate so remarkable among geologists, is the fact that it contains seven specimens of the lower jaws of quadru peds belonging to some animal of the Opossum family. The remarkableness of this circumstance is, that it is the first instance of mammalian remains being found under the tertiaries. The animals to which these jaws belonged are called Amphitherium and Phascolotherium. The Stonesfield slate, as represented by the flaggy sandstones of Collyweston, Northamptonshire, contain Trigoniæ like No. 8. 6. The Inferior Oolite, or Cheltenham stone, has for its characteristic shells, Terebratulæ, like No. 6 and No. 14, and, in Normandy, an Ammonite, very much like a Trochus, No. 9, called Pleurotomaria ornata. III. SOME GEOLOGICAL PHENOMENA OF THE 1. The entire series of the oolites are a marine formation, constituting one distinct geological period. The oolitic period indicates many great changes, but still the whole formation is marked throughout with its own group of plants and animals developed or introduced in succession. 2. The structure of the inferior oolite shows that the clayey bottom of the sea, of the lias period, became sandy-the sand being loose and micaceous. Such a change in the depth and the nature of the sea bottom rendered it fit only for a distinct group of fish and sheils. 3. This sea bottom became sandy, probably by a depression or subsidence of the Liassic coast, and by the consequent wear and tear of the neighbouring land. The sand covering the clays of the lias before they had perfectly hardened, formed a basis for the great masses of limestone about to be deposited. 4. The sea bottom became now sandy and limy, and accordingly the sea animals became modified and changed in some degree. 5. Soon, a deposit consisting nearly of pure carbonate of lime was formed, in a sea which allowed it to collect in round minute particles, of an egg-shaped form, now called colite. This form of deposition was not continued unbroken throughout the whole period, but was repeated at different intervals, until strata of about 300 feet were accumulated. 6. Such a condition of the sea was favourable to the existence and development of shell-fish. These grew and abounded for many ages, till their dead and broken shells collected and formed thick bands of shelly clay, which afterwards hardened into limestone. At the same time, the sea abounded with fish adapted to feed upon such shell animals. 7. In the earlier ages of the oolitic ocean, but very few corals were growing on the bottom of the sea; but at the close of the great oolite age, the bottom of the ocean abounded with Encrinites, or the stone lilies, No. 15. And 8. After this, it appears, as if the land that formed the sea bottom was again elevated, so as to form a shallow sea. now the waters of this shallow sea became full of mud, which smothered and killed the Encrinites. They seem to have been destroyed in vast multitudes, partly by the muddy contents, and partly by the force, of the sea current, for their remains lie scattered in all directions in the Bradford clay. 9. It is evident from these clays and sands, that land was not far off, for they were constituted by the degradation of such land, by the weather, and by running water. This land was clothed with rich vegetation, such as indicates a warm climate, and abounded with forests. The trees would shelter and feed many inhabitants, among which would be beetles and fies. Quadrupeds also of the Opossum family occupied the open part of the country. The waters were peopled with crocodilian monsters, some of which will be described in our next lesson. 10. After the politic rocks had been formed in stratified beds, they became exposed to the action of running water and other agencies, and were, in consequence, extensively destroyed. This is very evident in the west of England, from the numerous outliers of it which exist, from the deep valleys of denudation which are found in it everywhere, and from the exceedingly winding and sinuous courses, and deep indentations, of its flanks, where it terminates on the lias to the west. II. The sandstones of the forest marble are often ripplemarked, and filled with fragments of shells and pieces of drift wood. This shows that they were formed on a coast. These ripple-marked slabs bear also the impression of foot-prints of animals like crabs, that walked over the sand while it was wet and soft. Impf. ind. ε-τρίβον, opt. τρίβ-οιμι. Fut. ind. (τριβ-σω) τριψω, οpt. τρίψουμι, inf. τριψειν. Aor. 1. ind. ε-τριψα, subj. τριψω, οpt. τριψαιμι, imp. τριψον, inf. τριψαι, part. τρίψας. Perf. 1. ind. (τε-τρίβα) τε-τρίφ-α, subj. τε-τρίφ-ω, imp. τε-τρίφ-ε, inf. τε-τρίφ-εναι, part. τε-τρίφως. Plupf. 1. ind. (ε-τε-τρίβειν) ε-τε-τρέφειν, opt. τε-τρίφ-οιμι. Middle Voice. Pres. ind. τρίβομαι, subj. τρίβ ωμαι, imp. τριβ-ου, inf. τρίβ εσθαι, part. τρίβ-ομένος. Impf. ind, ε-τρίβ-ομην, opt, τρίβ-οιμην. Fut. ind. τρίψομαι, opt. τριψοιμην, inf. τριψεσθαι, part. τριψόμενος. Plupf. S. ε-τετριμ-μην D. ε-τε-τριμ-μεθον Ρ. ε-τε-τριμ-μεθα Fut. 3. ind. τε-τρίψομαι, opt. τε-τριψοιμην, inf. τε τριψεσθαι, part. τε-τρίψομενος. Passive. Aor. 1. ind. (ε τριβ-θην) ε-τριφ-θην, subj. τριφ-θω, opt. τριφθείην, imp. τριφ-θητι, inf. τριφ-θηναι, part. τριφ-θεις. Fut. 1. ind. τριφθησομαι, opt. τριφθησοίμην, inf. τριφθησεσθαι, part. τριφθησομενος. Aor. 2. ind. ε-τρίβην, subj. τρίβω, opt. τρίβ-είην, imp. τριβ-ηθι, ητω, etc., inf. τρίβ-ηναι, part. τρίβεις. Fut. 2. ind. τρίβ-ησομαι, opt. τρίβ-ησοιμην, inf. τρίβ-ησεσθαι, part. τρίβ-ησομενος, η, ον. Verbal adj. (τριβ-τος) τριπ-τος, η, ον; τριπ-τεος, εα, εον. Passive, τετριμμαι Verbal adj. τρεπτος, τρεπτέος. κοπτω κοπ-τ-ω, I knock. Active. Middle. Fut. Aor. 1. Fut. 3. κε κοφα κοπτομαι κεκομμαι, like κε-κοπα (Hom.) Aor. 1. εκοφθην κυψω κόψομαι έκοψα εκοψαμην Verbal Adj. κοπτος, κόπτεις. Fut. 1. κοφθησομαι Αor. 2. εκοπην Fut. 2. κοπησομαι So conjugate καμ-π-τ-ω, I bend, fut. καμψω, aor, εκα perf. mid, or pass, κεκαμμαι (instead of κεκαμμ-μαι). Ο παις την επιστολήν εγεγράφει. Οἱ πολεμιοι πρέσβεις εις την πολιν επεμψαν. Οίνος και τα κεκρυμμενα φαίνει βυσσοθεν. Παν ύψος εν θνητῳ γενει περιετρεψεν η χρονος η φθονος. Τας των σπουδαίων φιλιας ουδ' αν ὁ πας αιων εξαλείψειεν. Σοφοκλής μετα την εν Σαλαμίνι ναυμαχίαν περί τροπαιον γυμνός αληλιμ. μενος εχόρευσεν. Μυρμηκες γης μυχατους οίκους προλελοιπότες έρχονται βιοτου κεχρημένοι. Πολλακις οργή ανθρωπων νοῦν εξεκάλυψεν. Τῳ Επαμεινονδου σωματι συνέθαψε την δυναμιν των Θηβαίων ὁ καιρος. Της αρετης τον πλούτον ου διαμειψομεθα τους χρημασιν. Ευριπίδης εν Μακεδονία τέθαπται. Θεος τοις ανθρώποις το μέλλον κεκαλυψεν. Οἱ Λακεδαιμονίοι ετραφησαν εν σκληροις ήθεσιν. Ακουσας καλόν μέλος τερφθείης αν. Ρημα παρα καιρον ῥιφθεν ανέτρεψε πολλακις βίον. Οἱ φωρες ἡμιν τα χρήματα κεκλοφᾶσιν. Οἱ πολέμιοι την πολιν ανατετροφᾶσιν. Οἱ στρατιωται τας τάξεις κατέλιπον. ENGLISH-GREEK. πε- πλέξομαι Passive. Aor. 1. ε-πλεχ θην. Aor. 1. ενταχθην. Fut. 2. ταγήσομαι. Verbal adj. πλεκτος, πλεκτέος; τακτός, τακτέος. Inflections of the Perf. Mid, or Pass. τάττω, I arrange, and σφιγγω, I compress. 5. τέταγμαι Indicative. Imperative. εσφιγμαί τέταξε εσφιγξη τετακται εσφιγκται τεταχέω εσφιγχθώ D. τεταγμέθον ἐσφιγμεθον τεταχθού τετάχθον Ρ. τεταγμέθα τεταχθε Infinit, τετάχθαι, εσφιγχθαι; Partep. τεταγμένος, εσφιγμένος. The letter has been written by the boy; the boy was writing the letter; the boy wrote the letter; the boy has written the letter; the letter had been written ; the letter will have | Μεταλλάττω (char. γ), 1 ebeen written; the letter may be writter.; the letter might be written. Ambassadors were sent into the city by the enemy; | Ταράττω (char. γ), I disturb, ting will send ambassadors into the city; wine often. Ταραχη, ης, ή, disturbance, Ξένος, a stranger, as a noun, what man has concealed in his heart; with the body of a guest. disorder. nondas was the pcwer of the Thebans buried; the Φυλαττω (char. 7), 1 guard; Αφρων, or, mindless, senseless, has been hidden from men by God; God has hidden foolish. ature; God will hide the future; the Lacedzmonians | Κραζω, I croak, cry out, mid. I guard myself against. | Λιαν, very, very much. |