ing rain, it follows, from a great number of observations, that the indications of this instrument are then extremely probable. As to the sudden variations, either in the one direction or in the other, they indicate bad or stormy weather. If to these considerations be added the observations on the direction of the winds and the the piece K to the lever B, and to the plate A which presses on the temperature of the air, indications may be drawn from the barometer, which are very useful for agricultural purposes. But it must be remarked that the table showing the relation between the height of the column and the state of the weather is the result of old and numerous observations in some particular locality; and that it is not adapted for every country in the world, or even for every place in the same country. In every country, the indications of the barometer are greatly modified by the geographical position of the place, and this must always be taken into account in the accurate construction of such instruments. The Wheel Barometer, or Weather Glass.-As an elegant piece of household furniture, and not as a philosophical instrument, the wheel barometer is specially intended to indicate good or bad weather! It is sometimes called the dial barometer, because it is furnished with a dial and index like a clock, see fig. 76. This instrument is merely a siphon barometer furnished with a mechanism which is put in motion by the rising and falling of the mercury, see fig. 76. ' on two circular springs D. These springs, pressing upwards, act upon the lever p, and oppose the pressure on the part M. Now, suppose that the atmospheric pressure increases, the top м is pressed down, the lever p is lowered and transmits its motion by springs D. But this plate carries an arm which rests on a rod E; and this rod by means of a bent lever H, communicates the motion to a chain o wound on the axis of an index c; and thus the chain conveys its motion to the index. Under the index is fixed a dial, fig. 78, which is experimentally graduated so that its indications may agree with the barometers of MM. Fontin and Gay-Lussac. The aneroïd barometer is very sensible and very portable; but the number of pieces in it is very considerable. When we come to treat of the manometer, a barometer of new construction, and without mercury, will fall under our notice. As the barometers we have described are chiefly of French construction, the scales in our engravings have been marked with the initials of the words used by the makers of these instruments, and with their graduations in millimetres, a millimetre being 039371 of an inch, or very nearly one-twenty-fifth part of an inch. Accordingly, we give below a table of the initials engraven on these instruments, the French words for which they stand, and the corresponding English words; the number of millimetres In this mechanism a pulley o is fastened to the axis of the index, and over this pulley a cord passes, carrying a weight P at one extremity and at the other extremity an iron float, a little heavier than the weight; this float rests on the mercury in the smaller branch of the barometric tube. If the atmospheric pressure increases, the level of the mercury falls in this branch, and the float descends and moves the pulley and the index from left to right. The contrary motion takes place when the pressure diminishes, because then the mercury rises in the smaller branch of the tube, and causes the float to rise with it. If the instrument has been carefully constructed, the index will point to the words changeable, rainy, fair weather, &c. when the barometer takes the heights corresponding to these indications; but this is so seldom the case in the instruments brought to the market, that they can only be looked upon as pretty philosophical toys. The Aneroid Barometer.-A new kind of barometer, in which no mercury is employed, has attracted notice for some years past, known under the name of the aneroid barometer (from the Greek, signifying a Liquidless Barometer). This instrument is constructed by M. Vidi of Paris, and was originally suggested by M. Conté, a learned member of the French expedition into Egypt. The parts of this instrument are shown in fig. 77, and in fig. 78; the whole is represented as enclosed in a case with a dial, its diameter being only about 3 inches. The principal part of this barometer is a cylindric.reservoir M, made of brass, and having the top very thin and flexible. A vacuum is made in this reservoir, so that the atmospheric pressure tends always to push in the top part M. But upon this top are fixed two uprights 8, which, by means of a eonnecting bar, press on a lever p, intended to balance the pressure For this purpose, this lever is fixed to a bar K, which oscillates freely on two pivots placed at its extremities. By means of a lover B, this bar K is connected with a plate A, which presses upon M. Measurement of Heights by the Barometer.—The pressure of the atmosphere decreasing in proportion to the elevation of the place to which the barometer is taken, the height of the barometer follows the same law, and thus it becomes an instrument for determining the altitudes of mountains. It was, in fact, soon observed that when the altitudes of the places of observation increased in arithmetical progression, the densities or pressures of the atmosphere decreased in a geometrical progression. The following approximate table of the densities of the air at different heights above the surface of the earth, will give some idea of this principle. to the law of progression in the density, or rather in the rarity of speaking, however, this acid seldom comes before the notice of the chemist; moreover its compounds are characterised by their difficult solubility, hence it may be considered as “hors de combat.” Applying the facts just deduced, remembering that the grand combustion-supporting function is strongly developed in chlorate of potash-remembering that nitrate of potash (nitre) is a congener of the former, and that it is an essential component of gunpowder-you will now know, if you did not know before, the reason why gunpowder burns when rammed into a gun from which all the atmospheric air is excluded. Gunpowder carries within itself combustibles-charcoal and sulphur, and a supporter of combustion, 1000 log. oxygen (in the nitre)-hence it is totally independent of the aid of atmospheric air. Many gunsmiths are so ignorant of chemistry, that they are not aware of the true conditions under which gunpowder burns. You may sometimes see a little hole drilled in the side of a gun breech, the use of which, gunmakers will tell you, is to let in the air and promote the burning of the powder. This is simply ridiculous. D=60346 (1+.002837 cos) (1+2 (1+1) H in which D denotes the vertical distance, in English feet, between the two places whose difference of level is required; H, the height of the barometer at the lower station, and the height at the upper station; T and denote the corresponding temperatures of the air on the centigrade thermometer, at the stations respectively; and ø, denotes the latitude of the place. M. Oltmans has constructed tables by means of which this formula can be easily calculated in metres; the only difference being in the factor 60346 feet, which in the original formula is 18393 metres. These tables, with the manner of using them, are to be found in the "Annuaires des Bureau des Longitudes." The student will find a similar formula with an example worked, in "Miller's Hydrostatics." If the altitude to be determined by the barometer be not very great, one observer alone can perform the experiment; but if the altitude be very considerable, and requires a long time between the observations in order to complete the ascent, the pressure of the atmosphere may vary, and it will then be necessary to have two good barometers. One of the observers with one barometer then remains at the foot of the mountain, while the other observer ascends to the top with the other. At a given hour, each observes his own barometer, and thus the true height of the column at each place, the true difference of the columns, and consequently the true difference of level between the places are accurately obtained. The most prominent characteristic of oxygen, as you are now aware, is its property of supporting combustion; the idea would seem likely enough, then, that a substance containing so much oxygen as does chlorate of potash, and delivering up this oxygen so readily, should also be a powerful supporter of combustion. We shall see. In the first place, the powder does not want air; in the second place, through this hole no air could enter, seeing that the expansive force of the inflamed gunpowder is outwards. This little hole facilitates the loading of guns-rifles especially, and facilitates also the escape of foul air or vapours: beyond this it is of no service whatever. Seeing that nitre is a congener of chlorate of potash, you may perhaps ask whether it might be used instead of the chlorate for the purpose of yielding oxygen gas. Yes; it sometimes (unmixed with oxide of manganese) is used for this purpose; but yielding up its gas with greater difficulty, it is less efficient. You perhaps also ask, whether the chlorate might not be used instead of nitre as a constituent of gunpowder? Theoretically I might answer Yes; but practically, No. Gunpowder made with chlorate of potash is far too explosive for safety. Not only would there be danger of explosion from the act of ramming, but the danger attendant on the manufacture of such gunpowder on a large scale would be frightful. The French tried the manufacture during the wars of the great revolution, and are even said to have used chlorate gunpowder in one of their campaigns; but the frequent explosions which occurred at the powder-mills led to the final abandonment of the process. A very simple, though indirect, method of demonstrating tho facility with which chlorate of potash evolves its oxygen is as follows. Powder two or three grains of the substance separately, and an equal weight of brimstone separately; incorporate these on a piece of paper, by means of a feather or other soft body; wrap the mixture in a piece of paper, plans the envelop on an anvil or other hard surface, and strike it smely with a hammer. The Occasionally the experiwhole explodes with a vivient rer. ment is varied by rubbing a few grains of chlorate of potash and an equal quantity of sulphur sharply together in a mortar, by a series of sharp short strokes, or rather downward pushes, half stroke, half blow, when a series of explosions results. When percussion guns first came into use, this mixture of sulphur and chlorate of potash was employed as the material for charging caps; the lock, that its employment was soon abandoned in favour of the so-called anti-corrosive caps, in which fulminating mercury takes the place of chlorate of potash and sulphur. We will now return to the consideration of gaseous oxygen. but the result of its combustion was found to be so destructive to Dissolve some chlorate of potash in water; dip into the solution a piece of paper (blotting-paper is best); dry the paper, and bring it into contact with flame or a red-hot coal. I do not wish the paper itself to burst into flame, but the contrary; if therefore this should occur, blow out the flame, leaving a mere ignited paper If oxygen gas be so powerful a supporter of woed and other ordiedge. Remark now how curiously the ignition traverses the nary combustibles, the supposition would appear likely, from à paper, which no longer burns as common paper. I dare say you priori reasoning, that bodies incombustible in atmospheric air, or will recognise something like this phenomenon. You will say it imperfectly combustible, should readily burn in this gas. I do burns like touch-paper. Touch-paper indeed it is, of the best qua- not know whether you will be surprised to be informed that iron, lity; far better than you could have made with the ordinary agent and indeed all metals without exception, are combustible. As -saltpetre; and now you may remember the following important regards iron, you have often, I doubt not, witnessed its combusfact: that" any substance capable of making touch-paper must con- tion when heated to whiteness in a smith's forge and rapidly tain an acid which holds five atoms of oxygen." Therefore, know-withdrawn, though probably you failed to reason on the bearings ing this rule, it follows that chlorate of potash, if placed before you as an unknown substance for examination, would at once have been determined as containing one out of four acids. of the phenomenon. We will now show how exceedingly combustible is iron in oxygen gas. There is an old-established conventional—a " lecturing" method of performing the combustion of iron in oxygen gas, which I will describe further on. It is well adapted for display in lecture-rooms and generally on the large scale; but it is not the best adapted to the requirements of our little bottles. I shall modify the experiment as follows. Take a circular dise of tin plate, fig. 1, large enough to cover the mouth of your oxygen bottle, and perforate this pipe centrally with a little hole, just Now proceed as follows. Ignite the brimstone at the point of the needle, and plunge the latter into a bottle containing oxygen gas, fig. 2. Theneedle will burn vividly, throwing off sparks in all directions, some of which, in all probability, will stick in the glass, partially fusing it. I repeat that the mode of operation here described is not the most elegant, but it is the best adapted to the necessities of our present apparatus. The usual method of performing the experiment is by employing, as the gas receiver, a jar of this kind, placed to stand in a plate containing water, and covered with a glass pane, fig. 3; using a helical or corkscrew-formed wire of this kind, fig. 4. If you can procure some of these gas jars, well and Fig. 3. Fig. 4. good, you may employ them in performing the experiments about to be detailed; if not, you must be content to use large-mouthed bottles. EXPERIMENT.-Bore a hole through a piece of charcoal; pass through the hole a wire; bend the wire into a sort of knot underneath, and attach it above to a tin-plate disc and cork, as représented in fig. 5. Ignite the charcoal; plunge it into the jar or bottle, fig. 6; wait until the combustion has ceased; then secure the mouth of the jar or bottle with a glass pane. The charcoal will Fig. 5. Fig. 6. burn with extraordinary splendour, and the sole result of combustion will hereafter be found to be a gas, invisible like oxygen, but totally dissimilar to it in every other characteristic. soldering at the point marked . These instruments are termed by chemists deflagrating ladles, and serve the purpose of exposing to the action of gases, liquids or fusible solids. We shall require two of these ladies; one for the purpose of igniting sulphur, the other for the purpose of igniting phosphorus, in oxygen gas. Ignition of Sulphur.-Having put a little sulphur into one of these deflagrating ladles, attached to a cork and disc in the manner already described, ignite the sulphur by heating it in the flame of a spirit-lamp. When thoroughly ignited, dip it into a jar or bottle containing oxygen. Remark the character of combustion-the pale blue lambent flame, the small amount of light, the gaseous nature of the result of combustion. When the sulphur has ceased to burn, cover the receiver or bottle with a glass pane, and put it aside. EXPERIMENT.-Combustion of Phosphorus in Oxygen Gas.I am about to mention certain details connected with the performance of this experiment, and you must attend to them implicitly, otherwise your experiment will fail, and yourself, most likely, will be severely burned. Pour a lump of phosphorus from the water in which you will purchase it, into a plate of water; cut off a very little lump (not bigger than a pepper-corn) under water; remove the piece thus cut off, not with the finger and thumb, but a pair of tweezers, scissors, or something of that sort; dry it by contact with blotting paper; put it into a deflagrating ladle; ignite it by contact of a hot wire applied to its surface, not by a flame applied underneath the ladle; plunge it into a bottle or a jar containing oxygen, and remark every peculiarity of the combustion which ensues. Preserve the results of this combustion, as you have preserved the others. The examination of all these products shall be the subject of our next lesson. LESSONS IN GEOLOGY.-No. XLIX. BY THOS. W. JENKYN, D.D., F.R.G.S., F.G.S., &c. ON THE CLASSIFICATION OF ROCKS. ROCKS OF RECENT FORMATION. THE rocks which contain fossils, and which on that account are distinguished by the name of fossiliferous rocks, have been divided by geologists, generally, into three series: The lowest contain the most ancient forms of animal existence, and are therefore called paleozoic (from raλalóg, palaios, old, and ¿wn, zoé, life), that is, old-life rocks. The series resting upon the paleozoic are called secondary rocks, or mesozoic (from jusros, mesos, middle, and Cwn, zoé, life), that is, middle-life rocks. The series resting on the mesozoic are called the tertiaries, so called because their beds contain a third form of organic life. In the lowest and in the middle series, all the imbedded fossils are remains of animals altogether extinct. In the third series, or the tertiaries, the lowest group of rocks contains some extinct species and a few of existing species; a higher group contains less extinct species and more of the present race; and in the highest group, there are extremely few of the ancient species, and à vast majority of the species which now live. On these accounts, the tertiary series, according to the comparative amounts of extinct and existing fossils which they contain, have been called Eocene, Meiocene, and Pleiocene; terms which will be explained in our next lesson. All the tertiary beds contain fossils of the present race of animals; but the group called the Newer Pleiocene by some, and Pleistocene by others, contains so much as 95 per cent. of the present species, and is therefore called a rock of MODERN formation. But, in the order of superposition, there are series of rocks much higher and newer in geological sequence than the Pleistocene beds; rocks which are characterised by having all their fossil shells identical with the species that are now living. It is this fact that distinguishes the lowest of these beds from the newer pleiocene, or rather the pleistocene, whose deposits always contain some proportion of an extinct species. It has hitherto been found difficult to coin a term or a phrase that shall properly and fully express the geological characteristics of these later groups of rocks. Some have called them Post Tertiary, others Post Pleiocene, and some continental geologists have tried to introduce the name Quaternary, or the fourth series, a term which seems as admissible as the word tertiary for the underlying rocks; and in some works they are called RECENT formations. It will answer all the purposes of this lesson, if we agree to designate all the beds which contain the fossil remains of the existing races of plants and animals, by the term POST PLEISTOCENE rocks. This class of modern rocks comprehend not only those strata which can be proved to have originated since the creation of man, but also sedimentary beds of much greater extent and thickness, which contain no signs of man or his works, but enclose remains of species of animals identical with races now living. It is true that in some of the lower beds of even these modern rocks we find the bones of ancient quadrupeds, such as the mammoth, the mastodon, the megatherium, &c., species that probably never co-existed with the human race; nevertheless the shells that are found fossil in these beds are the same as those of testacea now living. N. B. In the rocks of this ante-historical period, all the fossil shells are of the species now living; they are destitute of human remains; and the bones of quadrupeds imbedded in them are partly of extinct species. It is right to say that you will not find this distribution of the post pleistocene rocks, either by name or by arrangement, in any work on Geology; and that it is made solely to facilitate your progress in the knowledge of this particular formation. This series is divided into three groups of rocks, viz. rocks that are now in the process of formation; rocks that have been formed since the existence of man; and rocks that have been deposited since the creation of the present race of plants and animals. I. ROCKS NOW IN THE COURSE OF FORMATION. Your attention has been already directed to the rocks that are now in the process of formation, in the lessons which have been given on the reproductive agency of fire, water, and wind, as agents of change in the crust of the earth. You are therefore prepared for the statement that rocks are being formed in our own day. 1. PEAT BOGS. Peat mosses are well known in all the mountainous districts of the north of Europe and America. They are divided into two distinct classes: first, immersed formations produced by the accumulation of aquatic plants, such as reeds, sedges, &c.; and secondly, the emerged formations, caused principally by the growth and decay of the plant called sphagnum. Some peat mosses lie frequently in highly inclined planes. Near Kiel, in Northern Germany, vast beds of peat show the two formations superimposed, where the peat has first grown in a basin or hollow several feet deep, and when it has reached the surface of the water, the emerged formation has commenced. A third mode of peat growth has been observed in the Vosges, and in Denmark, where, in deep, but small basins, the peat-forming plants have begun to grow at the surface of the water, and the basin has become gradually filled by the immersion of the floating turf, and this continually thickened by the growth of new plants. You may easily think that such abysses, concealed by verdure, have often proved dangerous to travellers and to cattle. These basins are filled with numerous bones and instruments of various kinds, both ancient and modern, which give a clue to the different epochs in their formation. 2. DELTAS OF RIVERS. The streams and brooks which issue from mountain sides are all charged with earthy particles, which they deposit in the beds of rivers as mud, gravel, and pebbles, and thus gradually form alluvial plains. If the force of streams be strong, the current transports an immense quantity of detritus to the mouths of rivers, where they form the accumulations of silt and sand, called deltas. In these deltas are imbedded the leaves of plants, branches of trees, remains of animals, shells of fish, human bones, and works of art. Specimens of such formations are supplied by some of our rivers in England, especially the Mersey, the Dee, the Severn, and the Thames; but they are presented on a large scale by such rivers as the Nile of Egypt, the Ganges in India, and the Mississipi in North America. To constitute a series of deposits a post pleistocene group, it is not necessary that they should always be found superimposed upon the Tertiaries, for sometimes they may be found resting on the most ancient rocks. In the annexed diagram, a a represents rocks of the greatest antiquity, and d the antehistorical deposits; e, the rocks formed since the creation of man, and b rocks that are now in the process of formation. Fig. 1. Recent Deposits Resting upon Ancient Rocks. 3. SUBMARINE DEPOSITS. You have already seen in the lessons on the agency of running water, that rivers which deposit their gravel and sand in deltas, carry their finest particles far into the bosom of the sea, where, after having been transported by currents and agitated by the waves, they finally settle down as a sediment on the deep and quiet floor of the ocean. Colonel Sabine, in his calculations on the sediments carried down by the river Amazon in South America, has shown that strata are now forming in regular deposits over great spaces of the bed of the ocean. system of DREDGING carried on by scientific men, uniformly shows that the strata which are now deposited in the bed of the sea, are pebbly where the waters are much agitated, sandy where the agitation is moderate, and argillaceous or clayey where the waters are comparatively quiet. The At Besides these rocks deposited mechanically in the sea by rivers, it is well known that there are many beds now in the course of formation by the chemical agenty of the calcareous, siliceous and ferruginous matter which is swept by rivers into the ocean. the mouth of the Rhone in the South of France, calcareous beds are now forming in the Mediterranean. On the shores of the Red Sea à rock formation is now in progress, composed of sand, gravel, corallives, fragments of older rocks, weed, pottery, and bits of wood washed up by the sea and cemented together by carbonate of lime slightly coloured by oxide of iron. 4. THE GROWTH OF CORAL Rocks. The best modern instance of the formation of coral rocks is found in the Bermudas, and the Bahamas. The coral reef in these districts consists of masses of numerous species of madrepores, astræa, and several others, 1 growing confusedly together, without any other apparent order than that of accidental succession and aggregation both upwards and sidewards. In the cavities of the mass are found fragments of corals, shells and other organic remains, perfect or broken, sand and chalky mud, and the whole becomes solidified into a compact rock by the aid of calcareous cement, while the upward growth of the living coral, and the accumulation of loose material on the surface proceed at the same time together. The coral work is ever in progress until it reaches the surface of the water. The loose materials are either dispersed through the crevices and inside of the reef, which thus pack and cement it together, or else they are carried landward or seaward to form the compact bases of other formations. British Museum an indisputable specimen of a human skeleton, found imbedded in a rock of solid limestone formed on the shores of Guadaloupe. This rock can be proved not to belong to the class of ancient limestones, but to be a very recent alluvial formation; for it contains, besides shells of the present sea, fossil arrows, stone hatchets, and pieces of rude pottery. A battle between the Caribs and the Gallibis took place on that spot in 1710, and there is every probability that this is a skeleton of one of the slain, either buried there, or sunken and imbedded when the coralline mass was soft. 5. SALT FORMATIONS. Very little is known of the origin of rock salt, and geologists have not been able to decide whether the precipitation of salt is owing to evaporation, or not. It seems clear that, in the basins of lagoons, lakes, or inland seas, pure salt can be formed only in the central parts of such basins, parts where no earthy sediment could be brought by currents, and where no sand could be drifted by winds. We cannot say what chemical processes are now going on in the quiet depths of the Mediterranean, the Red Sea, and the Dead Sea; but the Runn of Cutch in the delta of the Indus, and some of the lakes in the districts of Mount Ararat, explain to us how beds of salt are formed in the present day. Professor ABICH, in his notice of "the Natron Lakes in the plain of the Araxes," says that in one lake, at the north-west foot of the Greater Ararat, the water, in the warmest season, retires three or four feet from its usual banks, on which a crust of salt a few feet broad and about half an inch thick is found deposited, of generally a pale rose-red colour. Other lakes lying to the south-east of Little Ararat, are of the same description. One of them is remarkable for having a broad zone of white clayey soil covered with luxuriant reeds and grasses. This soil forms the margin of the lake all round, and is so soft that the feet sink in it. It is covered with an accumula-feet above the high-water level, overlying the raised coral beach, tion of irregular lump-like incrustations of a very compact salt, of a white colour and inclining to red, and with a foliated structure. These saline crusts lie all around the white shore, chiefly floating in the water of the lake; and some fragments that were broken off floated about, like shoals of ice, on the deep-red surface of the water, which had all the appearance of water just on the point of freezing. On examining the floor of the lake, as far as could be done by tying several Cossack spears together, it was found covered with a similar saline crust in unbroken continuity, and appeared to increase in depth, from the shore, in such a manner as to leave no doubt that a layer of salt, several inches thick, extends over the whole bed of the lake. Our space will not allow us to consider other rocks that are now will not allow us to consider other rocks that are now forming as sheets of lava, as volcanic cones, and as sand dunes. II. ROCKS FORMED SINCE THE CREATION OF MAN. Every honest geologist acknowledges that he is not able to mark the point of union between historical and geological time, and that he cannot define where geological epochs terminate, and the historical era begins; that is, that he cannot tell, from the contents of rocks, at what time man appeared on the earth. If we might be allowed to argue in the old Aristotelian method, we might infer that, where we find in existence a large number of animals that seem to contribute to the use of man, we have also some evidence of the existence of man: for, if the bones of the ox, the horse, the dog, the deer, &c., the bones of animals which are characteristic of the present creation, are found in the sediments of ancient lakes or the alluvium of ancient floods, there is nothing to prevent the indirect inference that the race of man had commenced when such beds were deposited. When the attention of men was first directed to organic remains found in rocks, many fossil bones were mistaken for the bones of man. In 1577, Professor PLATER, of Basle, found near Lucerne, the bones of a man, which he made out to be a giant nineteen feet high. These turned out to be the bones of an elephant. SCHEUCHZER published an account of a fossil skeleton, under the title of "Homo Diluvii Testis," or man a witness of the deluge. Cuvier afterwards proved that this was the skeleton of a gigantic salamander or proteus. SPALLANZANI gave an account of a hill in the Island of Cerigo, that consisted of fossil human bones; but BLUMENBACH showed satisfactorily that all of them belonged to quadrupeds. Sir Alexander Cochrane brought and placed in the The circumstance that has occasioned the greatest perplexity to geologists is, that some signs of human contrivances, and even human bones, have been found in caverns, mingled with the bones of animals that are certainly extinct as to those districts, if not absolutely extinct as to the globe at large. As far, therefore, as mere geological evidence is concerned, it would be unsafe to say that man has not been a inhabitant of the earth for a much longer time than modern chronologists assert. As to the human bones which have been found mixed with those of extinct animals in certain caverns of Belgium and France, all of which seem to have been deposited at the same time during the formation of the most recent tertiary strata, Dr. Buckland has shown that the human remains must have been introduced subsequently. That some rocks have been formed since the creation of man, is evident from the fact that they contain the remains of human beings, implements of human art, and several vestiges and traces of the operations of man. In basins or hollows covered with peat mosses, and in districts known as submerged forests, human bones and works of art are imbedded in company with the remains of recent animals. On the west shore of the Red Sea a rock has been formed composed of sands, gravel, corallines, pottery, and weeds, cemented by carbonate of lime, being in thickness from an inch to three or four feet, and sometimes alternating with thin and loose layers of shingle. This rock stands at five or six and inclosing bones of camels and fish which to this day contain animal matter. On the shores of Sicily, Greece, Asia Minor and Aden, similar marine calcareous rocks have been formed. Rhodes, at the height of six feet above high-water mark, a calcareous conglomerate is observed that contains fragments of ancient pottery, recent shells, and. pebbles of limestone, gneiss, basalt, serpentine and porphyry. In several places on the calcareous cliffs that skirt the Mediterranean between Alexandria and Aboukir, there is a bed, about a foot thick, consisting of bleached human bones, derived from the ancient Roman and Greek cemeteries, intermingled with those of the slain in battle in the neighbourhood. These bones are covered with a layer of sand and gravel, varying in thickness from a few inches to three or four feet. They appear to have been washed into their present position by the drainage water running from the higher grounds to the sea. What is remarkable in these bones is, that though they are in an excellent state of preservation, they are not fossilised. At |