UC-NRLF B 3 121 fl7D c c< * ,- C ' :.^ r c ^ .^CC< C **. =1 . ( < ( i < c c which fill up metalliferous veins, rarely have any relation with, or de- pendance on, the rocks containing the veins. We may also consider that they form of themselves two distinct classes of phenomena ; the mass of the contents being usually either silex, fluorspar, or carbonate of lime, all in a crystal- line state, and together forming what is called the veinstone, and the substance we call ore, which contains in some form or other the metallic produce. This latter it is the object of the miner to extract, and he only regards the rest in propor- tion as it enables him to judge with greater or less certainty of the abundance or absence of the ore. But mineral substances in which no trace of metallic ore is found, or which do not contain it in sufficient proportion to be worth extracting, much more frequently fill the veins, and are greatly more abundant than the others, and it becomes necessary for the Geologist to observe them accurately if he wishes to arrive at any knowledge of the general laws which have influenced the filling of the veins ; for this knowledge can only be arrived at by carefully study- ing all the facts on record with reference to the nature of their contents, and the uniformity of direction that charac- terises each kind, (those namely which are productive and those which are unproductive of metallic ore,) in the same district. It is rare that veins containing crystalline quartz, fluor- spar, or carbonate of lime, are entirely without metallic ore in some form, and the ore then usually occurs either in 252 NATURE OP MINING OPERATIONS, small veins within the principal one, or in grains or crystal- line masses, and disseminated crystals. Other veins, how- ever, in which the veinstone is earthy or powdery, are very rich in ore, while those which are altogether sterile are generally filled with sandstone or clay, or with broken fragments of the adjacent rocks. The distribution of ores in the vein is exceedingly irre- gular, and the relation which exists between the various cir- cumstances of magnitude, extent, or inclination of the beds is not in the smallest degree known. Many isolated facts have, indeed, been recorded on this subject, but so contra- dictory do these facts appear, that no satisfactory general theory has yet been deduced from them. A change of thickness appears to have great, but variable influence on the metalliferous contents of a vein ; and where the vein swells out and bifurcates in such a way that the sum of the thickness of the bifurcations is greater than that of the vein, there is said to be very generally not only an increased quantity, but an improved quality of ore.* In many veins the nature both of the veinstone and the ore, is observed to be different at different depths, but it is not at all the case that the vein becomes richer as we follow it in the deeper sinkings. Veins, however, are manifestly changed whenever the containing walls change from sedi- mentary to crystalline, and even the mechanical condition of the walls of the vein has sometimes exercised an impor- tant influence on the contents. In Cornwall there often appears to be a certain degree of * This is the case in the Veta-Grande in Mexico, a vein worked by twenty-one mines, and on a line nearly a mile and a half long. The richest portion in the whole of this great extent is also the thickest, where the vein attains a thickness of more than ten yards. On the other hand, where it is nipped in, and becomes not more than from three to four feet wide, it is comparatively poor, and hardly worth working. MINERAL VEINS. 253 order in the arrangement of the metallic ore in the veins ; but, however this may be, it seems an almost univer- sal law that a change of rock is characterised by an instant alteration in both the metalliferous and earthy minerals of the lodes, and this, not only in passing from one rock to another of different mineral composition, but even when the containing rock is altered only in hardness and texture. So commonly is this the case that the intelligent miner looks to such appearances with greater anxiety than even to the vein itself, and they are considered by him among the most certain indications upon which he can venture to confide. In the older rocks, and especially in Cornwall, a vein, productive of copper ore in slaty ground, and entering granite without any change of direction or break of conti- nuity, becomes, perhaps, at first richer, and furnishes ores differently mineralised, but if pursued far into the granite it is almost always observed to become poor.* When, how- ever, a productive vein crosses an elvan or granitic dyke, the ore sometimes becomes rich and abundant, but some- times vanishes altogether. It is worthy of remark, that the granite of Kit Hill, and of Dartmoor, have hitherto, with a single exception, yielded tin ore only, whilst the slate series of that district contains ores of copper, lead, and silver, but scarcely any tin. In the lead mines of Derbyshire, which traverse alterna- ting bands of carboniferous limestone and the erupted rock called toadstone, the veins which are thick and valuable in the limestone are nipped in, and become valueless when passing through the trap. In the mining district of Als- * It is considered in Cornwall that the productive copper mines are always upon the junction of granite and killas ; in other words, that the veins are only valuable where there is a change of country. 254 NATURE OF MINING OPERATIONS. ton Moor again, where cracks and fissures in the stratified rocks contain the productive veins of lead, although the same fissure is common to a very considerable number of alternations of limestone, carbonaceous shales, and gritty sandstone, the lead ore is never found abundantly except in one bed of limestone. From this bed (about twenty- three yards thick) four-fifths of the whole metallic produce of the district is obtained, the remainder being distributed among eight other limestones, eighteen gritstones, and twenty-eight beds of shale, having a total thickness of 260 yards. It appears, indeed, that nothing can be more variable and unaccountable than the relation of the metallic ores in a mineral vein to the circumstances of position of the vein, but that in spite of this there exists throughout a certain amount of order, and an approach to regularity. In all districts, traversed by mineral veins, there are, for instance, what may be called systems of veins, each system being characterised by some peculiarities of position or contents, and each, so far as we can judge, referrible to a distinct period. In Cornwall there have been described eight such systems, and the same number had been observed by Werner, at Freyberg. It will be right to allude shortly to the nature of these. In Cornwall the first class of veins are those which appear to have been the earliest formed, and they form a very large majority of the whole number in the district. They are the older tin veins ; they underlie to the north, and are traversed by those of the second class, which are comparatively few in number and of small im- portance. These two classes include all the lodes from which tin ore is extracted ; their width varies from a mere string to MINERAL VEINS. 255 as much as thirty-six feet, and most of those which are productive range east and west. The third class of Cornish veins are the east and west copper lodes, and these form the greater number of all the copper lodes in the county ; they always cut across the tin lodes when the two kinds meet, and they are usually ac- companied by small veins of clay. The fourth class consist of what are called the contra copper lodes, and are few in number ; their direction is N.W. and S.E., or at right angles to those bearings. The fifth class includes the cross courses, which run N. and S. or nearly so, and contain no tin or copper, though sometimes a little lead ore : their underlie is various ; they are tolerably wide, and have been traced on the surface to considerable distances. The remaining three classes are of comparatively small importance to the miner, but they are valuable as adding to the number of facts on the subject of mineral veins. One of them includes the recent copper ores, and another the corresponding cross courses, while the last includes the slides, (composed wholly of slimy clay,) and consisting of a number of narrow imperfect veins, rapidly underlying, and running in all directions. In almost every case the productive veins run east and west, and the cross courses north and south, and the more recently filled fissures and partings are composed almost wholly of clay, so that, as a general rule, veins which con- tain a greater quantity of this clay traverse those which contain a smaller quantity of that substance. The systems of veins in the Freyberg districts are de- scribed by Werner, and offer a series of facts somewhat analogous to those observed in Cornwall, but the metals are different, and so also are the prevailing directions of the 256 NATURE OP MINING OPERATIONS. lodes. The first, and most ancient, are chiefly north and south, and include those veins from which the chief supplies of lead and silver have been obtained. The second system (contra-lodes) are more argentiferous, but much thinner. Their direction is about north-east and south-west. The veins of the third system are all north and south, and those of the fourth at right angles to them, being what are called in Cornwall cross courses. They both contain lead glance. The others are less important. In the English lead districts, the systems of veins are much more simple than in Cornwall or Saxony; the di- rection of the productive veins is, almost without exception, east and west, and they are traversed by cross courses, not productive, at right angles to them. The underlie is sel- dom considerable, and it is tolerably uniform throughout the district. On the whole, and viewed with reference to the whole district, the direction of the productive veins in Cornwall is also strikingly uniform, and the mean of nearly three hun- dred observations, recorded by Mr. Henwood, gives 4 S. of W.,* while the actual direction in nearly two- thirds of the number, differs but little from the average. * Cornish Geol. Trans, vol. v. p. 250. The actual number of observations tabulated is 295 ; of this number the direction in 182 instances was between W. and S.W., and in 62 others between W. and N.W. Dividing Cornwall into ten districts, the mean direction of the veins in seven of the districts is much more south of west than the general mean, as the other three districts chiefly contain the contra lodes. The volume from which this and some other notes are taken, is entirely filled with an elaborate account, by Mr. Henwood, of the Metalliferous deposits of Cornwall and Devon ; and this account, taken in connexion with Sir H. De la Beche's Report of the Geological Survey, leaves little to be desired with regard to the economic Geology of mining in this interesting district. Mr. Kenwood's Work contains an enormous mass of detail with regard to all the principal matters connected with mining, and must form an admirable text book for the mining student and the practical miner. MINERAL VEINS. 257 Besides the productive veins or lodes, all mining dis- tricts are traversed by other veins, usually at right-angles to the former or nearly so, but which are rarely metalli- ferous ; or which, if they are so, contain some kinds of ore not abundant in the lodes. The principal minerals in these cross courses are quartz and clay, the quartz being usually crystalline. In Cornwall it has been found that out of one hundred and sixty-three cross veins, whose directions were taken, one hundred and eighteen bear between north and north-west.* Having thus described the chief phenomena that have been observed with reference to the appearance of mineral veins themselves, it remains only to consider their rela- tions with one another, and the circumstances under which they may have become a part of the rocks now containing them ; and I shall endeavour to shew, in the first place, by such evidence as I can bring before the reader in a few pages, that veins must in almost every case be of more recent origin than the rocks which contain them. I have already, in speaking of the different systems of veins, as- sumed that they were not all of the same age, and I shall also, before concluding the present chapter, offer such proof of this as will, I think, be satisfactory. Werner long ago attempted to prove, by a number of arguments, the truth of these important facts. He shewed the probability that cracks and fissures which may here- after become mineral veins have ever been> and are still forming, and he directed attention to the fragments of ad- jacent rocks often found in veins, as a proof that the filling up of the veins must have been subsequent to the consolida- tion of the rock. But he also asserted, from observation, the important and unanswerable fact that veins intersect * Loc. cit. p. 259. VOL. II. S 258 MINERAL VEINS. one another ; a vein of newer origin often displacing an older one, breaking its walls, and altering its texture and contents at the place of contact. A more modern fissure also often extends through the adjoining rock into an older one, and the two veins join, and run parallel for a short distance, while sometimes a new fissure is permanently stopped, coming in contact with the tough walls of a former vein. The vignette, at the commencement of the present chap- ter, is an instance of the intersection of veins, and can only be rationally explained by supposing that the intersection which has taken place was accompanied by a slip or fault which has produced the shifts observed in the older vein. The relation which veins bear to the rocks or beds in which they occur, and the nature of their internal structure, composed of different kinds of minerals, also seems to indi- cate very clearly that every fissure, and therefore also, a fortiori, the filling up of the fissure, is more recent than the formation and consolidation of the rocks, and it will even appear that we may often determine the general direction of veins in a district, by observing that of the disturbing forces, and the directions they have taken. The relation that exists between these disturbing forces and the fissures in the rocks being thus made evident, there can no longer be any doubt of the fact that veins are of posterior origin to the rocks they traverse. Werner concludes his argu- ment thus, " Wherever I have seen veins of considerable size crossing each other, I have always found that they had been formed at different periods. For when two veins of different directions and inclinations meet, one of them always intersects the other, and this in its turn may be traversed by a third, and so on. In this way we see that the first rent had been filled before it was traversed by a MINERAL VEINS. 259 second, and that this, in like manner, was filled before a third was formed." As an instance of singular complication arising from the intersection of veins in faulty ground, I subjoin a vertical section from one of the Cornish mines, in which it is not easy to see at first the nature of the disturbances that have VERTICAL SECTION OF INTERSECTING VEINS. HUEL PEEVOR MINE, CORNWALL. a, a', a". Tin vein. ft, b'. Copper vein. c, d. Faults, or slides. ^ produced such an effect. A little consideration, however, will shew that the tin vein (a) has been first displaced by the intersection of the copper vein (5) accompanied by an upheaval to the south. Afterwards, the displaced vein of tin, and the vein of copper have both been affected by the fault (c) which has carried them downwards to the north, and lastly, the fault (d) has again heaved a portion of (a) upwards to the south. The ground plan of these disturb- ances is exceedingly complicated. On the whole, then, it may be concluded as probable, from the nature of the case, and as completely borne out by the facts recorded, first, that mineral veins are of various ages and quite independent of the age of the rock in which they occur; secondly, that the fissures which now form mineral veins have not been filled up without some refer- ence to the nature of the rocks in which they are contained, and that the filling up was therefore, in all probability, sub- s2 260 MINERAL VEINS. sequent to the formation of the fissure ; and, thirdly, that the fissures which contain metalliferous ore are chiefly in certain definite directions, constant in the same locality for the great majority of instances, but that these are crossed nearly at right angles by another set which are unproductive. We shall see, in the next chapter, how far this direction of productive and unproductive veins has reference to the ge- neral structure of a country, and how far it may be sup- posed to be due to forces acting through very extensive districts. VIEW OF CROAGH PATRICK. 261 CHAPTER III. ON THE DISTRIBUTION OF MINERAL VEINS AND THE EXPLANA- TIONS THAT HAVE BEEN OFFERED TO ACCOUNT FOR THE PRINCIPAL FACTS CONCERNING THEM. MINING DISTRICT. VAiE OF GLEN-DA-LOUGH, COUNTY WICKLOW, IRELAND. THE different metals and metallic ores are not found mingled at hazard with the various rocks of which the earth's crust is made up, nor are the mineral veins of which we have been speaking in the last chapter indif- ferently distributed in all parts of the globe, without reference to the nature of the rock that may predomi- nate. So far is this from being the case, that we find many extensive districts utterly without any trace of mineral riches, while others again are abundantly sup- 262 MINING DISTRICTS OF ENGLAND. plied ; and these differences are not unmarked by Geogra- phical as well as Geological phenomena, concerning both of which it is necessary that I should now give some account. It will be obvious to any one acquainted with the va- rious districts celebrated for their mineral riches, that while, almost without exception, those districts are remarkable for their hilly and even mountainous character, so, on the other hand, the widely extended plains of Europe, Asia, and, America are either entirely deprived of such sources of wealth, or possess them very sparingly. These facts with regard to the Geographical distribution of metalliferous veins are not a little remarkable, and they become more interesting when considered with reference to the Geological structure of the same districts. Our own island occupies the first place among all the countries of Europe, and even exceeds them all in respect of its mineral riches. Cornwall, Derbyshire, and Cumberland, are the three mining centres in England, and each of these districts is also remarkable for its mountain character. Cornwall furnishes all the tin, and seven-eighths of the copper produced in England.* The undulating barren sur- face of this county, its granitic axis rising at different points to the height of from 1000 to nearly 1300 feet above the sea -level ; the abundance of Devonian schist (or kittas) and mica slate, and the great granitic dykes called elvans, which penetrate the mechanical rocks, all mark the district as unfit for the ordinary operations of agriculture, and in that respect poor and barren ; but although the landscape is desolate, this very sterility often indicates a surface which covers mineral treasures, and the * The Isle of Anglesea, and some other districts in North Wales, supply nearly all the remaining copper ore. It is needless to remark, that these localities offer no exception to the generalisation offered in the text. MINING DISTRICTS OF THE BRITISH ISLANDS. 263 bare granitic bosses become the scenes of mining operations, scarcely anywhere exceeded in practical value. The other districts in the British Isles most remarkable for their mineral riches, differ, of course, in some points of detail from Cornwall and Devonshire. In Derbyshire ores of lead are extracted from the hilly country of the neigh- bourhood of the Peak, so well known, and so often visited for its picturesque beauty. In Northumberland, Durham, and Cumberland a wide extent of high moorland is inter- sected by the valleys through which run the Tyne, the Wear, and the Tees, and many branches which feed these rivers ; and the deep fissures forming these valleys lay open to view numerous veins of ore (chiefly of lead, like those of Derbyshire,) and direct the operations of the miner to the places where it is sufficiently abundant to reward his toil.* The elevated tracts of Wicklow, (a view of which is represented in the vignette at the commencement of this chapter,) Wexford, and other parts of Ireland, the hilly * The picturesque features of a country are so nearly associated with, and so dependant on, its points of Geological interest, that I think it will not be out of place to allude here to some of the beautiful and interesting scenery in the north of England characterising the district from which a considerable portion of the lead used in England is obtained. I select the Northumberland and Durham dis- trict, because I believe it is much less visited by the tourist than Derbyshire or Wales. The lead-mines of the north of England are chiefly worked in the vicinity of Alston Moor, where the three counties of Northumberland, Durham, and Cum- berland meet together, and from the lofty and bold hills of which the three rivers, the Tyne, the Wear, and the Tees, take their origin. Of the valleys through which these rivers run, Weardale is perhaps the most beautiful, but Teesdale the most romantic. Both sides of Weardale, for some distance along its lower part, present the richest vegetation and great rural beauty. The soil is fertile, the crops abundant, and much woodland is interspersed, but the patches of trees become rarer as we ascend the valley, and towards its upper part the trees are solitary, until we rise to the wild, treeless, heath-covered hollow in the mountain, which forms the head of the dale. The river Tees rises in a hollow at the foot of Cross Fell, and flows for many miles through a desolate valley, with a little grass land on each side, and here and 264 MINING DISTRICTS OF FRANCE. country of Flintshire, and other parts of North Wales, and some of the mountain districts of Scotland, are also well known, and have been worked to advantage for their mine- ral produce. In France there are five districts in which metalliferous ores are found, and in each case they occur in schists of a very ancient Geological period, which have been much frac- tured and disturbed by the subsequent intrusion of igneous rock. The first of these districts is that of Brittany, which greatly resembles Cornwall in its Geological structure, and also, though on a smaller scale, in its Geographical con- figuration, and which contains ores of tin and argentiferous ores of lead. The mining district of the Vosges is the most promis- ing among all those that have been hitherto worked in France, and contains some veins of great value, from which ore has been extracted from time immemorial. The argentiferous ore of lead, occurring in veins both numerous and extensive, forms the principal source of mineral pro- duce, and although at present it is not worked, it offers every prospect of success to the adventurer. The veins traverse gneiss, and they form two systems nearly at right- angles to each other, the north and south system being the most productive, but the cross courses also containing several metallic ores. A considerable number of valuable ores of iron are found in this district. there a solitary tree. At a most romantic spot in the upper part of Teesdale the river dashes over a precipice of sixty-nine feet, and further down in the valley there are a number of exceedingly beautiful spots embosomed in wood, with the Tees flowing on the south side, and the hills receding to a considerable distance. The town of Alston, the mining centre of the district, is beautifully situated close to the river Tyne. The valley of the Tyne below the town is richly culti- vated, and for about five miles above it ascends, between lofty hills, to where the river rises, in a hollow, at the foot of Cross Fell ; this picturesque mountain giving a character of considerable grandeur to the surrounding scenery. See Appendix to First Report of Mining Commissioners, part ii. p. 721. MINING DISTRICTS OF SPAIN. 265 The great platform of Central France forms a third centre of mineral riches, and the chief produce, as in the Vosges, consists of an argentiferous ore of lead contained in veins traversing the mica schist with great uniformity in a north and south direction. Besides this ore of lead an ore of antimony (chiefly the sulphuret) is abundantly distributed through some of the veins, but these are of no great thickness, and occur near the contact of the gneiss and mica slate, which wrap round the granitic centre, and are therefore in the vicinity of igneous rock. Ores of copper, manganese, galena, blende, and an oxide of chrome are also found distributed through some of the veins of this district. The chain of the Pyrenees is not without indications of mineral wealth, consisting chiefly of ores of iron con- tained in a white saccharine altered limestone of the secondary period, which is associated with schistose clay. Mines of copper and argentiferous lead ore have been for- merly worked, but are now abandoned. The fifth, and last mining district of France, occurs in the French Alps, where, near Grenoble, some small veins have been worked containing iron ore and native gold.* Other mines of lead and iron have been formerly worked, but are now neglected. Spain has long been celebrated for its extensive and valu- able mines of quicksilver and lead. The former metal is ob- tained chiefly from Almaden, in the province of La Manche, from mines which have been open since the time of the Romans. Cinnabar is the principal ore, and it occurs in veins from SO to 40 feet thick, extending in an east and west direction for more than a mile. The lead is said to * This mine was feebly worked during part of the last century, but not to pro- fit. After being neglected for half a century, it was again undertaken in 1837 : I do not know with what success. 266 MINING DISTRICTS OF GERMANY. occur in calcareous beds, associated with schists and crys- talline rocks, and is found in masses very near the surface. Italy presents, in many places, valuable metallic produce, the iron ores of Elba being among the most remarkable and abundant in the world. Some other metallic ores are also found in different parts of Southern Europe. The mines of Germany are known throughout Europe as the cradle and school of scientific mining operations. They are numerous, rich, and very varied. The Erzgebirge, a chain of mountains separating Saxony from Bohemia, and the Hartz, the most northerly mountain range in Germany, are the principal seats of mining opera- tions in Northern Europe, and are both of them extremely interesting ; the metals obtained from them are silver, cop- per, lead, and iron, together with some tin and cobalt, the latter chiefly from the Saxon mines. One of the most remarkable veins in the Erzgebirge, is the stockwork of Zinnwald, which contains veins of oxide of tin in a hemispherical mass of large -grained granite. In this district, however, the chief metalliferous ground is gneiss, and in the Hartz, also, the central granite of the Brocken is surrounded with gneiss and clay slate, and surmounted by grauwacke schist and limestones of the Devonian period, the chief localities of the productive veins being in the metamorphic rocks. Austria possesses mineral riches of considerable value in the Tyrol, in her veins of iron ore, (with which a small quantity of gold is associated,) while in Hungary the same precious metal is obtained from veins, in which native silver, copper, argentiferous galena, blende, and iron are all pre- sent. The principal mining works in Hungary are near Chemnitz, where granite, gneiss, and mica schists form the containing rocks. MINING DISTRICTS OF RUSSIA. 267 Scandinavia, under which name both Sweden and Norway are comprised, contains numerous mineral veins, chiefly in a hornblende rock bursting through schistose beds and limestones of the Palaeozoic period. The ores, both of copper and iron, in this district are probably the most extensive and the richest in the world, but their position in the country rendering it exceedingly difficult to transport them, has prevented their being worked with much energy. The Ural chain has long been remarkable for its mineral riches, and both that chain and the Altai, (separating Siberia from Tartary,) are exceedingly remarkable, as the source of auriferous sands, which have been long known, and of which there seems a never-failing supply. The gold of Russia is chiefly obtained from these sands,* but veins of it have also been worked of late years. The gold is contained in quartz, charged with oxide of iron and pyrites, and these minerals are often so grouped to- gether, that it would appear as if the gold, originally en- tangled with the pyrites, had only been liberated by the decomposition of the latter mineral. The silver and lead ore worked in the Altai mountains is contained in veins occurring in chlorite schist, which is sometimes crystalline and porphyritic. The mass of the vein is composed of quartz : in the upper part of the vein the ores are ochreous, and in the lower part sulphurous, and at certain points the ore is so abundant as to replace the quartz. * To give an idea of the proportion of gold in these sands, I may mention, that from the year 1830 (when their existence was first discovered) up to 1835, 282,000 tons of sand had undergone the process of washing, to obtain the metal, and the quantity of gold produced amounted to about fifteen hundred pounds avoir- dupois, or about the twelfth part of an ounce per ton, on an average ; but this pro- portion only applies to those sands which have already been sifted and prepared for washing. 268 MINING DISTRICTS OF SOUTH AMERICA. The Ural chain is chiefly interesting for its copper ores, which often occur at the contact of igneous rock with limestone. It is from these mines that the finest speci- mens of malachite are obtained,* and the veins also abound with iron ore, and contain both platinum and gold. It is principally on the Asiatic side of the chain that the mine- ral veins are worked. South America has been celebrated for its mineral riches from the period of the first discovery of the New World, and although it was chiefly the rich gold and silver ores that originally excited the cupidity of mining adventurers, it is well known that the ores of copper and of some other metals are equally abundant, and perhaps almost equally valuable. They may be considered as forming several principal groups, of which Brazil deserves to be first alluded to being the district in which the ores of gold predominate, almost to the exclusion of all the others. It is chiefly the mountainous province of Minas (formed of metamorphic rocks of no very ancient date) that con- tains those of the Brazilian mines which have been longest worked for the most precious of all metals. Gold and platinum are there found native, disseminated with ores of iron and manganese in stratified rocks. The whole dis- trict is much disturbed and broken up by the crystalline rocks in the immediate vicinity, and is intersected by dykes of porphyry and hornblende, and veins of quartz. The entire series of stratified rocks, which consist of gneiss, altered sandstones, and chloritic schists, have been pene- trated throughout by metallic particles, and these some- times become so dominant as to conceal the original character of the formation. ~f* * One block of this valuable mineral has been found weighing more than forty tons : It is greatly used for ornamental purposes. t The diamond is also found occasionally in these mines, in a white quartzose MINING DISTRICTS OF SOUTH AMERICA. 269 The district in the chain of the Andes which contains the principal veins of silver ore, is situated in Peru, and includes the celebrated mine of Potosi.* The veins here occur in clay slate, regularly stratified ; the veinstone is quartz and carbonate of lime, and the metallic ores consist of pyritous ore of iron, galena, and blende ; the silver being quite subordinate. These veins are generally very much inclined to the horizon, and are sometimes parallel to the stratification of the containing bed. The Cordilleras of Chili contain an extensive series of valuable mining districts, producing much silver, associated with rich ores of copper and some gold. The ores are richer towards the north, and their value is generally increased where they approach the contact of igneous rocks with the limestones of the western part of the chain. These limestones are of the cretaceous period, and the metalliferous veins often follow the lines of their contact with the porphyries and granites, the igneous rocks having forced their way through the limestones, and the planes of contact on each side the central axis (which runs north and south) being marked by a succession of valuable metallife- rous veins. Of these veins, that series which occurs on the eastern side contains silver, and is separated by an in- tervening mass of porphyry, which is sterile, from other ores of silver and copper at the contact of the porphyry with granite, while still further to the west, and behind matrix, and is associated in the same district with other precious gems, such as topaz, euclase, and beryl. The gems are contained in talcose druses (or crystal- line hollows in veins) confusedly, and are mingled with crystals of white quartz. * The metalliferous ores of Potosi, the richest that are known after those of Mexico, offer a good instance of a fact not uncommon in argentiferous veins. The mineral, extremely rich near the surface, diminishes in value as it descends, and in the deeper part of the mine is scarcely one-eightieth part so rich as at the top. This is paralleled in the celebrated Dolcoath mine, in Cornwall, the deep work- ings of Avhich have been for some time neglected on account of their poverty. 270 MINING DISTRICTS OF NORTH AMERICA. another range of porphyries, are the auriferous ores co- vered by vast masses of modern trachyte. North of Chili, and still running parallel to the great chain of the Andes, the contact of porphyries with me- chanical rocks of doubtful antiquity, but which have been altered by the action of heat, is still marked by rich veins of silver ore, upwards of six hundred of which are worked, some of them at a height many thousand feet above the level of the Pacific. From one set of these mines alone (the Pasco mines) about 180,000 pounds weight of silver is annually obtained; the ore occurring in masses, asso- ciated, as usual, with iron, and distributed through quartz. Still further north, in Colombia, Guatimala, and Mexico, the same abundance of mineral riches obtains, and always in the direction of the great mountain chain. North America also, is not without rich and valuable mineral produce of various kinds, chiefly occurring in the Rocky mountains, the Andes of that continent, but also in some of the inferior mountain chains both in the west and north. Considerable veins of copper ore are found in the northern and north-western states, and abundance of iron, besides several other metals.* * Amongst others, Chrome and Titanium are worked to profit in some parts of Pennsylvania. The ores of these metals were at first turned up in ploughing the fields, but they are now obtained by regular mining operations. " What is called the Gold region in the United States may be described as a metalliferous belt extending in a south-west direction through the States of Vir- ginia, North and South Carolina, and Georgia. The length of this belt is about six hundred miles, and it has a mean breadth, from its southern to its northern edge, of about eighty miles. In every part of this extensive line native gold is met with in alluvial deposits, and in various streams, whilst the contiguous rocky strata abound in quartzose veins, more or less auriferous, and either found in a formation of which talcose slate is the characteristic rock as in Virginia or sheathed with talcose slate, and holding an almost vertical position in elvan beds and beds of ferruginous slates, as in North Carolina ; so that talcose rocks charac- terise the entire gold region from one extreme to the other." Feather stoneliaugfrs ' Excursion through the Slave States." 1 Vol. ii. p. 350. London, 1844. DISTRIBUTION OF MINERAL VEINS. 27 1 Several important results may be arrived at from a due consideration of the phenomena of the Geographical dis- tribution of mineral veins, and the general appearances presented by them at the surface. In the first place, it would seem that they occur almost invariably in mountain districts, and are more or less immediately connected with disturbances of strata and with great lines of dislocation, or are in the immediate vicinity of igneous rocks. M. Necker, struck by these facts, which are very evident in a large number of cases, has investigated the subject of mi- neral veins with reference to these three questions,* viz. first, whether there is any unstratified rock near each of the known metalliferous deposits? secondly, whether, if none such appear at the surface, there is any distinct evi- dence or any high degree of probability that an unstratified rock exists immediately under a metalliferous district, and at no great distance from the surface ? and, thirdly, whether there are found any metalliferous deposits entirely uncon- nected with igneous rocks ? The first of these questions may certainly be answered in the affirmative, by reference to a vast number, forming the great majority, of cases of known mineral veins in all parts of the world. The great mining districts in all countries have been shewn to be immediately connected with unstratified and crystalline rocks. In answer to the second question, M. Necker refers to a number of instances in Europe where mineral veins occur nearly and evidently associated with unstratified rocks, though not actually proceeding from or passing into them. Such is the case, for instance, in the Isle of Elba, where an abundant supply of iron ore is obtained from veins in sedimentary rocks, but the close vicinity of erupted por- * Proceedings of Geol. Soc. vol. i. p. 392. 272 DISTRIBUTION OF MINERAL VEINS. phyries and other igneous rocks, and their actual appear- ance at the surface not far from the veins themselves, is sufficient proof of their presence in considerable abun- dance. With regard to the third question, the answer is, although not absolutely in the negative, yet sufficiently so to add great strength to any argument that might be deduced from the answers to the former questions. The quicksilver mines of Idria in Carinthia, and the lead veins in the mountain limestone of Flintshire and the south-west of England, are among these apparent excep- tions ; but the former occur in a district nearly connected with the great elevations of the chain of the Alps in its continuation eastwards, and the latter are not far from considerable dislocations and disruptions of the carboni- ferous strata. Besides the important fact, that the presence of mineral veins is almost always accompanied by indications of the action of subterraneous disturbing forces, and often by the actual presence of igneous rocks, we also learn, from a general consideration of the phenomena of veins, that they are, for the most part, uniform in direction in particular districts, and have a very remarkable tendency so to arrange themselves that the line of their direction shall either be north and south, or at right angles to those bear- ings. In England, more than half the metalliferous veins are east and west; and this is so uniformly the case in many districts, that the east and west veins are commonly denominated right running veins, while those in the other direction are known as " cross courses." Observing how commonly it happens that mineral veins make their appearance in districts characterized by the presence of altered or metamorphic rocks, it might natu- DISTRIBUTION OP METALLIC ORES. 273 rally be assumed that they were chiefly confined to strata of ancient date. This appears, however, to be by no means the case, and metallic ores are known to occur in rocks of the secondary and even tertiary periods. And although the Generalisations attempted to be deduced by early Geolo- gists as to the age of metals, are not altogether borne out by facts, there still seems to be a certain order of antiquity in their arrangement, for tin has not hitherto been met with in any rocks of modern date, nor have the precious metals been obtained from the older veins. Apart from considerations of age, there are other circum- stances, dependant apparently upon local influence in the distribution of metals, which are also worthy 'of notice. The slates, for instance, of Cornwall and Devonshire, are of nearly the same geological age as those of North Wales and Cumberland, but the metalliferous ores found in them differ exceedingly, tin abounding chiefly in the southern counties, copper being the staple in the central and some parts of the northern, and lead in other parts of the northern district. It is true, indeed, that copper and lead are found with the tin in Cornwall, and that lead is associated with the copper of North Wales, and Coniston Water Head ; but there are indications of preference, if we may so say, which well deserve careful investigation. It is a fact of considerable interest, that the limits of mining districts are often very decided, and marked by peculiarities in the physical features of the country. In the north of England, the neighbourhood of Cross Fell has been worked with the greatest enterprise ; but no instance has occurred (it is stated by Professor Phillips) of a single vein being traced across the great Penine fault to the west. Similar facts have been observed with regard to the Flint- shire veins, which occur in the carboniferous limestone, and VOL. II. T 274 THEORIES OF MINERAL VEINS. which in no instance enter the Silurian rocks. In this lat- ter case, as in many others, the older rocks rise on the line of a great axis of disturbance, and seem entirely to cut off the whole of the mining ground. Having now very briefly described the nature, the posi- tion, and the contents of mineral veins, and the incidental circumstances attending their presence in particular locali- ties, it will be worth while to close the history with some statement of the nature of those theories, which have been suggested as sufficient to account for phenomena so re- markable and so extensively exhibited, and examine the explanations that have been offered of the most prominent and remarkable fact, namely, the original filling up of the mineral veins with the metallic oxides and metals in a crystalline state. Mr. Necker, in the paper already cited from the Geolo- gical Proceedings, considers it a necessary result of the connexion he has successfully endeavoured to shew be- tween veins and igneous rocks, that the method of subli- mation was the one adopted by Nature in almost every case to fill up those cracks and fissures in the crust of the earth, which have resulted in mineral veins. This theory of sublimation differs considerably from that of igneous injection proposed by Hutton, and both of them are diametrically opposed to the theory of aqueous deposi- tion as promulgated by Werner. This latter cause is, how- ever, manifestly insufficient to account for a large class of the phenomena of veins, although it may no doubt be true in some cases. It has never yet been proved possible for many of the metallic ores, and other minerals found in veins, to be so held suspended in water, that they can have been thence deposited in a crystalline state, while, on the other hand, there is every probability, from the appearance of THEORIES OF MINERAL VEINS. 275 the veins, that heat was actively employed, although con- nected in many cases with other and more powerful agents yet to be considered. The Huttonian hypothesis, that the contents of veins were in all cases injected from below in a state of igneous fusion, is scarcely more probable or better founded than the rival theory of the Saxon Geologist. That some, indeed, of the cracks in strata, such as trap dykes, have been so injected, there can be little doubt, be- cause in many cases we actually see the effects of heat on the rocks forming the walls of the dyke, and it is clear that quartz and many other minerals, and probably occa- sionally metalliferous ores, may have been forced up from below. But if this theory were really true, we should surely sometimes find the ores, as we do the basalt, pro- truding above the surface, and we could trace the direction of the currents in which the matter flowed, and discover some relation between the different masses of ore that occur in the veins. With regard to the theory of sublimation, by which it is meant that the minerals and metallic ores have been vola- tilized by heat, and afterwards assumed their place by con- densation, there can be no doubt of its being occasionally a vera causa ; but, like the other theories, it fails in universal application. Both this and the Huttonian theory of injec- tion would seem to require that veins should be richer in metallic produce as we descend to greater depths in a mine ; but I have already remarked, that present expe- rience is decidedly opposed to the existence of any such necessity. The most recent attempt that has been made to account for the phenomena of mineral veins, introduces a new agency, that of electricity ; and the advocates of this T o 276 THEORIES OF MINERAL VEINS. hypothesis consider, that by referring to electro-chemical action, many of the most characteristic and remarkable of the facts that have been observed may be satisfactorily ex- plained. The great improvements and discoveries that have of late years been effected in this branch of science, and the certainty that electricity is a most powerful force, acting incessantly, and aifecting even the minute structure of inorganic bodies, corresponding almost with the vital principle in its power of removing, re-arranging and select- ing the particles of dead matter, render every suggestion with reference to this force worthy of the most careful attention. The experimenter to whom science is chiefly indebted for the researches on which the electrical theory of mineral veins is. founded, is Mr. Robert Were Fox, who has greatly distinguished himself by a vast number of investigations on the mutual relations of electricity and magnetism, and their mode of action in re-arranging the particles which compose the crust of the globe. Assuming the existence of fissures produced in the solid substance of the earth's crust at various times, and taking it for granted also that they penetrate to great depths, are exposed to a high temperature, and must have been filled up progressively, Mr. Fox has shewn the probability there is of heated water having been circulated in them by ascent and descent, and the certainty that quartz and earthy sub- stances might be deposited from water in that state. He then proceeds to explain, that in such fissures, filled with metallic and earthy solutions, the different sorts of matter on the sides must necessarily produce electrical action, which might be rendered more active by the unequal tem- perature of the water and the walls of the fissure. Cur- rents of electricity thus generated would pass more easily THEORIES OF MINERAL VEINS. 277 in the fissures than through the rocks, and they would pass in directions conformable to the general magnetic currents of the district, and therefore east and west, or somewhat to the north or south of these points, according to the position of the magnetic poles at the period when the process was going on. Electrical currents thus circumstanced would deposit the bases of the decomposed earthy and metallic salts on dif- ferent parts of the rocky boundary of the vein, according to the momentary electrical state and intensity of the dif- ferent points; and the nature and position of the rocks would be influential in determining these conditions. When by such processes particular arrangements had happened, new actions might arise, and amongst them a series of secondary phenomena, such as the transformation of ores without change of form, a fact otherwise very difficult to comprehend. Lateral rents might also be filled by virtue of these new actions, even though they were not in the most favourable lines of electrical circulation. In confirmation of his views Mr. Fox has actually suc- ceeded, by direct experiment, in forming well-defined me- talliferous veins by means of voltaic currents operating under circumstances resembling those supposed to have occurred, and which sometimes do occur in Cornwall. Before bringing this subject to a conclusion, I may observe, as some, and perhaps a sufficient excuse for the uncertainty of our knowledge concerning it, that it is the most difficult of all departments of Geology, for it requires the closest investigation, combined with the broadest gene- ral views, while the means of pursuing such investigations are scanty and unsatisfactory, and the examination of mineral veins in the mines themselves is rarely productive of any useful result. It cannot, therefore, be a matter 278 THEORIES OF MINERAL VEINS. of surprise that different, and even opposite views, have been advocated by those who have only partially observed Nature ; and perhaps it is the safest plan, as it certainly seems the only way by which we can reconcile conflicting opinions, to take a middle course, and admit the validity of each cause that has been assigned. Nor is such a mode of escaping from the difficulties of the case unreasonable or inconsistent with what we know of the ordinary course of Nature, in which all means are used, and every variety of cause employed, to bring to perfection one great result. In examining the contents of veins, we cannot but be struck, not only by the ap- pearance of a complication of causes, but by the evidence of their succession, rendering it probable not only that dif- ferent agents have been employed, but that they have done their work separately as well as conjointly, that they have operated at different periods, and that one has pro- duced effects for which another was inadequate.* * See the Report of the third meeting of the British Association, p. 20. I think it right in this place to notice a Work recently published, and from which I had hoped to derive some useful information. I allude to Mr. Evan Hopkins's book, professing to exhibit the connexion of Geology with Terrestrial Magnetism. Carrying out the electrical theory of Mr. Were Fox to its widest, I might say wildest extreme, Mr. E. Hopkins seems to me to have \vandered so far into the realms of imagination as to mistake his excellent practical knowledge of certain mining districts for an universal acquaintance with the laws which govern the material universe. Dwelling on the universality of local appearances, he assumes hypotheses concerning the nature of magnetic action, which are not in any way borne out by the facts he adduces. I cannot help expressing my regret, that, in the present state of Geological science, any one should be found to generalise so exten- sively, and propose his generalisations to the notice of practical men with so much apparent conviction of their being well-grounded, and at the same time exhibit so very limited a knowledge of numerous facts and observations which ought to have been taken into consideration. 279 CHAPTER IV. THE NATURE OF THE OPERATIONS MADE USE OF IN DIFFERENT COUNTRIES FOR THE PURPOSE OF OBTAINING METALLIC ORES. EAST HUEL CROFTY COPPER-MINE, CORNWALL. a, adit level. b, deep adit. c, d, e,f, g, the diflerent shafts. The numbers mark the depths of the levels. The shaded portions of the diagram represent those parts of the lode that have been extracted. ONE of the chief results to be anticipated from an ex- tended diffusion of the true principles of Geology among practical men is, that each in his own profession will in time discover, that as there is an appearance of the action of general laws in the arrangement of the materials of the earth's crust, a knowledge of these laws will be useful in the economical operations in which he may be inter- ested. Whatever these operations may be (and whe- ther they refer to mining, engineering, or agriculture, it 280 APPLICATION OF GEOLOGY TO MINING. matters not), the practical man must in time study and observe for himself, and he will then learn to anticipate with certainty what result will take place from a known combination of circumstances. The effect of a series of observations carried on by intelligent men possessing a fair knowledge of Geology, might, and probably will, ul- timately, tend more to the advance of Geological science than the comparatively desultory work performed by the amateur, who is necessarily obliged to traverse with ra- pidity a district in which the constant resident finds many opportunities of study and investigation. With regard to that department of practical Geology which we are now considering, it must be confessed that at present the indications furnished of the existence of metalliferous ores by a consideration of the general order of superposition and age of the rocks of a district, are rather negative than positive, and scarcely do more than enable the Geologist to assert, that in such or such a spot there is no probability of the existence of productive veins. Still even this amount of knowledge is useful, and a more minute acquaintance with the disturbances and dislocations of the strata in a district already known to be metalliferous, is calculated to afford indications of the utmost value, and form a branch of practical Geology, from the careful pursuit of which the most interesting results may be anticipated. And after all, the discovery of the existence of mineral riches in a district is by no means a point of practical difficulty, while to decide whether such produce will repay the expense of bringing it to the surface and exporting it to distant countries must always depend very much on local circumstances, which have little immediate relation to Geology. STREAM-WORKS. 281 By examining the beds of mountain streams, and the gravel or loose stones brought down into the plain country, a knowledge of the existence of metalliferous veins in a district may often be attained. By following up the in- dications thus afforded, an idea of the actual position of the veins, and even of their extent and value, may also be acquired. This simple method was, no doubt, the one by which many of the richest veins were originally discovered, and it is still so far -pursued, that sifting the gravel and sand of many rivers in metalliferous districts is to this day a profitable undertaking, and in some cases is the only kind of research pursued. " Stream-works," as undertakings are called in which this method of obtaining ore is pursued, are in our own country chiefly or entirely confined to the ores of tin, which, from their great specific gravity, are readily separated by the action of running water from the lighter sands and gravel with which they are associated. The ores of tin worked in the island of Banca, in the eastern Archipelago, are entirely obtained in this way, and the quantity of ore brought down by the mountain torrents may be imagined when it is mentioned, that as much as 3,500 tons of tin have been exported annually from that island alone. In other cases, gold or silver, in a virgin state, is dis- tributed in small grains in the sand, and this is, in fact, the chief source of the precious metals from many dis- tricts in Europe, Asia, Africa, and even some parts of America. The sifting and washing of sand furnishes in this way nearly all the gold produced in Russia, both European and Asiatic ; the gold being found nearly pure, and mixed only with a small quantity of silver and platinum, in the state of small grains. An annual supply of about fifteen 282 STREAM-WORKS. thousand pounds weight of gold, and nearly five thousand pounds of platinum,* is thus obtained, (the latter metal chiefly from the sands of one stream), of which more than three-fourths is derived from the Altai mountains, which separate Siberia from Tartary. In our own country, the stanniferous gravels of Cornwall are not usually upon the surface, but are either covered with other gravel, or with clay, sand, or peat, which require to be removed before the fundamental rock is reached on which the tin-stones rest. The gravel when collected is thrown upon an inclined plane, upon which a fall of water is conducted, and then being worked about, the tin-stones, if of sufficient volume, and provided the force of the water is not too great, remain upon the inclined plane, while the lighter stones and earth are washed away. It is from this method of separating the ore that such works have been called stream-works. They are of com- paratively small importance now in reference to the general supply, but still afford employment to a number of the poorer miners. As, however, such a source must be, at the best, doubtful and uncertain, and one which in most districts would soon fail, it becomes necessary that the gravel should be gradually traced along the bed of the stream, by whose rapid cur- rent it has been brought down, until the metalliferous fragments of rocks, increasing in number and volume, at last point to the spot where the outcrop of a vein at the surface has been the origin of the supply. * Some interesting observations have been recorded by the Russian mining engineers with regard to these auriferous sands. It has been remarked, that they rarely repose on granite or syenite, but usually on schistose rocks, near serpentines and hornblende rocks. They are also found, not in the recesses of the mountains, but principally forming plateaux parallel with and terminating the chain, or exhi- bited in the lower and broader part of the valleys. They are not continuous, and in certain localities the gold is more abundantly distributed than in others. SHODING FOR THE LODES. 283 This method of arriving at the actual position of the vein is called in Cornwall, shading or sheading,* and is a method of great antiquity, being in fact an almost necessary preliminary to any regular mining operations. When the ore is thus discovered at its source, it is not difficult to determine whether it is a thick bed of gravel, a vein, or a mere lump of ore, and its direction and relations with the surrounding country may be more or less clearly made out. The early history of the Cornish mines, and the nature of mining operations in that country at the commencement of the seventeenth century are recorded in a very interesting manner by Carew.*|* u He first notices stream-works and lodes, and the opinion of the tinners that the tin-stones in the stanniferous gravels were derived from the lodes by the deluge. He next describes the process of shoding, which seems to have been then conducted much in the same manner in which it is now practised, and he notices that the shode for the lodes ' either lieth open upon the grasse or but shallowly covered. 1 Having found this shode 4 they next,' he says, ' sank pits of five or six foote in length, two or three foote in breadth, and seven or eight in depth, to prove where they may so meet with the load. If they miss the load in one place, they sincke a like shaft (pit) in another beyond that, commonly farther up towards the hill, and so a third and a fourth until they light at last upon it.'"{ If the lode thus discovered offered a fair prospect of success, the discoverer would usually associate others with * The fragments of ore which by rain or currents of water are torn off from the lodes or veins of ore, are called shoads. *f* Survey of Cornwall, by Richard Carew. (Reprinted 1769.) De la Beche's Report on the Geology of Cornwall, Devon, and West Somer- set, p. 527. 284 ANCIENT MINING OPERATIONS. him in the working, and the company of adventurers thus formed appointed a captain, whose duty it was to see that the men did their work properly, and who attended to the mine and to the pumps. The tools used were extremely simple, and consisted only of a pickaxe and shovel, but with these they would sometimes follow the lode to the depth of forty or fifty fathoms, the miners being let down and taken up by a rope wound over a winch. In cases, however, where the hang or inclination of the lode was considerable, the miners are described as working to a con- venient depth, when they sunk a shaft from the top " to admit a renewing vent, which notwithstanding, their work is most by candlelight." The loose work was kept up by timber, and the rate of progress appears to have been very slow, as we are told, " a good workman shall hardly be able to hew three foote in the space of as many weeks." * It will readily be imagined, that into pits thus sunk a considerable quantity of water would drain, and it is clear that this was an extremely troublesome and un- manageable difficulty, often inducing the abandonment of a valuable mine. The draining machinery is described as " composed of pumps and wheeles driven by a streame, and interchangeably filling and emptying two buckets and such like." In some cases, when the works were on a hill- side, canals were cut from the lode to the nearest con- venient valley, but they are described as being " costly in charge, and long in effecting." And even where these difficult and expensive means were resorted to, the water would still have to be raised from such of the workings as were below the level of the valley, and a speedy limit would be put to all workings where the ore lay deep beneath the surface of the surrounding country. * Carew, ante cit., p. 10, 11. WORKING OF MINES. 285 The description thus given of the superficial, and com- paratively simple works of a former age, is applicable in a very considerable degree to the more extended operations of the present day ; for, although the introduction of im- proved machinery has tended to increase the facilities of working at great depths, the only difference in principle is the establishment of an improved plan of working adapted to the nature of veins of different kinds, together with that attention to ventilation necessary in all underground operations that are at all extensive. The various operations which are included under the general expression " the working of mines," * may be con- veniently grouped under two heads, the first having re- ference to the preliminary and experimental works necessary to be undertaken before the commencement of mining on an extensive scale, and the actual processes of sinking shafts, driving galleries, detaching the ore from its matrix, and bringing it to the surface, &c. ; and the second com- prehending what may be called the incidental works of a mine, those namely, of drainage and ventilation, without a due attention to which no mine can be safely worked at all, while, on the careful and scientific attention to such de- tails, the safety of the miners and the profit of the mining adventurer mainly rests. * The French term ' exploitation ' expresses much better than our English word, ' working ' the important and varied nature of mining operations. " Sexploitation des mines," says M. Burat, " embrasse tous les precedes, moyens, ou methodes qui ont pour but Pextraction des matieres utiles ; cette ex- traction devant toujours etre sure pour les travailleurs et aussi economique que possible. Cette science doit encore definer le gite, veiller a son amenagement, afin de preparer et conserver pour 1'avenir les garanties de securite et de richesse. La science de Texploitation, ainsi compose'e de principes, de precedes et d'appareils derive a la fois des sciences geologique, physique, et mecanique ; elle comprend en outre des faits speciaux et des donn6es pratiques qui sont acquis aujourd'hui par les travaux de tous les hommes distingues qui en ont fait 1'objet de leur etudes." Geologic appliquee, par A. Burat, p. 218. 286 PRELIMINARY OPERATIONS OF MINING. The operations included under the first head, will be the objects of consideration in the present chapter, while the others, having reference to the extraction of mineral pro- duce from stratified deposits, as well as from mineral veins, will be more properly discussed after I have spoken of coal, and other substances obtained in a similar way. The preliminary operations of mining are necessarily de- pendent in a great measure on the nature of the rocks, whether they are penetrated by mineral veins or interstra- tified with mineral treasure, and on the amount of know- ledge possessed concerning the general structure of the district, and the extent to which similar works have been carried. They must also differ according as the mineral to be extracted is supposed to exist near the surface or at great depths. The indications on the surface that may be presented by a mineral vein, are not usually sufficient to attract general attention, and would in most cases be so entirely hidden by a coating of gravel and vegetable soil, as to exhibit scarcely any marks that would enable even the most experienced eye to recognise them. In the absence, therefore, of metal- liferous gravels which can be traced up the course of a stream to a hill-side, and to the actual outcrop of a vein, (and even then wherever many veins intersect,) the question must often be determined more by experiment and tact, than by any distinct indications of the spot in which it will be most advisable to commence sinking, so that the greatest advantage shall be derived from the vein, supposing one there to exist. In cases where the existence is doubt- ful, but a probability appears of mineral veins being disco- vered, a series of experiments called in Cornwall ' costean- mg? is undertaken with the view of discovering the pre- sence of a vein. This method of experimenting is derived PRELIMINARY OPERATIONS OF MINING. 287 from the supposition that the veins in the district follow some general law, and the operators, selecting a convenient spot, commence by sinking a pit through the soil, and to a small depth in the rock. Of course the chances are many against immediate success, but in case they find nothing, the next step is, to drive or cut a gallery from the pit a short distance in opposite directions, at right angles to the direction of the lodes found in the neighbourhood. In this way it is possible that they may ' cut the lode ;' but if still unsuccessful, they remove a few fathoms in the direction of the galleries, and repeat the same process until they have either discovered the lodes, or give up the speculation in despair.* In matters of this kind, although experience is often a better guide than abstract science, still there is no doubt that the person best able to bring his experience to bear will be one who is acquainted with the facts of Geology; and such an one will avoid many sources of error, because his conclusions will be founded on rational premises. The great secret of economical mining lies in the original adoption, and proper carrying out, of an uniform and well- digested plan of working, a plan that can only be pro- perly laid by the experienced mining engineer, who is able to add an acquaintance with Geological facts to sound practical and local knowledge. I am indeed most anxious to impress upon every one who reads these pages that, * I would not here so far offend against the common sense of my readers as even to allude to the absurdity, did not some practical men in our own country still credit the fable, that mineral veins may be discovered by a forked hazel twig, dig- nified by the name of a divining-rod. In the year 1830, and possibly at the pre- sent day, a person living at Redruth was so far notorious for his enchantments of this nature, that he was quoted with some degree of consideration in the Quarter- ly Mining Review, vol. i. p. 403, and others, perhaps, may be equally celebrated. I merely allude to the subject as a quasi method of discovering mineral ore and subterraneous springs, which may still be had recourse to. The prospects of suc- cess from the employment of such means I leave to the consideration of speculative 288 SHAFTS AND LEVELS. while the mere Geological theorist may be even more likely to fall into error in some cases than the mere em- piricist or 'practical man,'* it is the intelligent observing experimenter who is sure to succeed, and will most cer- tainly enlarge the bounds of knowledge, as well as benefit himself and all who confide in his guidance.* When the position of a mineral vein is ascertained, its direction known, and some reasonable conjecture made con- cerning its extent, thickness, and value, measures must be taken to obtain by subterraneous excavation the buried mineral, -f- and for this purpose pits or shafts must be sunk, and galleries, or, as they are sometimes called, levels, must be driven, which prepare the way for the convenient extrac- tion of the ore, and at the same time carry off, so far as may be, the water which either rises into the mine from springs or drains into it from the surrounding strata.^: Of such galleries, two sets must be driven at right angles to * Many interesting and valuable exemplifications of this truth are recorded in the life of William Smith, " the father of English Geology," as he has been in some respects justly called, recently published by Professor Phillips. It appears that the really scientific knowledge of Mr. Smith, acquired by the application of a philosophy purely inductive, was often available, and employed in purposes and results entirely practical. Improvements in draining of all kinds, and many inge- nious contrivances in the laying out and constructing of canals, were suggested to him in consequence of the knowledge he had attained of the facts of stratification, and were of the most vital importance in many engineering operations on a large scale. t I have confined myself in the text to a description of those works in which subterraneous operations are necessary. All mining undertakings are of this kind at some time or other, and till then they partake rather of the nature of quarries, to which I shall allude more particularly hereafter. t In the ordinary language of mining, pits open to the surface are called shafts; and in Cornwall those not open to the surface, but sunk from one gallery to another, have received the name of winzes. Horizontal galleries, excavated in metalliferous veins, are called levels, and those not in the metalliferous veins, cross-cuts ; but that principal gallery, or tunnel, through which the drainage of a mine is conveyed to the surface at the lowest convenient spot, is denominated the adit or adit-level. All excavations horizontally are called driving, those down- wards sinkings, and those upwards risings. FIRST OPERATIONS OF MINING. 289 each other, and both horizontal, one being in the direction of the strike of the vein, and the other at right angles to that direction. VIEW AND IDEAL SECTION OF MINERAL VEINS. Let us suppose a simple case like that represented in the cut, in which mineral veins crop out on the sides of a hill and follow a direction tolerably uniform. These veins let us assume to be of moderate thickness (not exceeding a few feet), extending to an unknown depth, and not greatly interfered with by faults. In such a case a pit must be sunk which shall reach the vein at a certain depth, but it will depend on the direction of the dip, or underlie, of the vein, (whether towards or from the valley or slope of the hill-side,) and on many other circumstances, as to where it will be most advisable to commence the sinking. In the case of the vein marked (1) a cross-cut (a) may be driven at. the lowest convenient point above the level of the highest water of the valley, and this gallery, having a gentle slope from the vein towards the hill-side, will form the adit-level, and be the channel through which the whole drainage of the works will be carried, while it may also serve for conveying out of the VOL. H. u 290 SINKING SHAFTS. mine the ore that is obtained. At (2) in the same sketch, the driving of an adit level (a') will be seen to offer similar advantages, but a difference will be observed in the arrange- ment of the shafts. In both cases it is found advisable to sink shafts on the upper side of the vein, but in (2) it is also convenient to have a sinking towards the slope of the valley, and which does not cut the vein. The shafts sunk upon a vein are not always vertical to meet the vein, but are occasionally commenced at the outcrop, and, where the inclination is not very consider- able, are continued in the substance of the vein itself.* This is not, however, so economical a process as it may ap- pear, for the difficulty of raising the ore is much increased, and there are many practical reasons which often render it expedient to sink at some distance from the outcrop so as to meet the vein at a certain convenient depth. The act of sinking a perpendicular shaft downwards to a depth where it is calculated the lode should be cut, may seem to require little further skill than is necessary to de- termine correctly the spot on the surface where the work is to commence. But the process in this way is exceedingly tedious, and in a mine at work where many galleries already existing are to be traversed, much greater rapidity is desirable. In such a case,-)- the shaft is sunk in several pieces, or, in other words, the sinking is commenced at the same time in several different levels, and no small skill is required so to lay out the work that the different portions of the shaft thus formed may exactly fit when they are connected together. An exceedingly small error of mea- surement in any one of these various and dark subterranean passages, would, in fact, be sufficient to throw the whole * In the diagram at the commencement of this chapter, the shaft (e) is a slant shaft, particularly in the deeper sinkings. t See diagram at the commencement of this chapter. ADIT-LEVELS. 291 into confusion, but such an accident rarely happens, although works of the kind are common in the Cornish mines.* In the same way, to drive an adit from one point to another through many fathoms of country requires great skill, more particularly where, in order to save time, the work is commenced from both extremities. Less than a quarter of a century ago (in 1824) great complaints were made in Cornwall of the condition of these channels ; and the necessity of attending carefully to the details of draining was insisted on, and the proper position of the adit pointed out by Mr. Carne. Owing to neglect in these matters, and to the want of good surface draining, a large quantity of water pumped up from the deep mines found its way back again among the workings, and this happened to so great an extent that since that period, greater attention having been paid to drainage, the quantity of water pumped is considerably diminished although the mines have become deeper and more extensive, and in many mines, where great care has been taken with reference to this sub- ject, the improvement has been very striking. Some idea may be formed of the extent of the drainage in mining districts from the fact that the various branches of the principal level in Cornwall, called the "great adit" which receives the waters of the numerous mines in Gwennap and near Bedruth, measure on the whole, about 26,000 fathoms, or nearly 30 miles, in length. One branch only (at Cardrew mine) extends for nearly five miles and a half, and penetrates ground seventy fathoms beneath the surface. The water flows into a valley communicating with a small inlet of the sea, and is discharged about forty feet above high- water mark.f * De la Beche's Report, ante cit. p. 563. f The total quantity of water discharged from mines in Cornwall by steam- u 2 292 PRINCIPAL SHAFT. In very extensive mines, such as are worked in Cornwall, it is necessary to have many shafts and a very considerable number of levels and cross-courses in order to carry on the general work of the mine.* In such cases there is usually a principal shaft of considerable size sunk through as many lodes as possible, and communicating with all the galleries. This shaft is often double ; one portion, called the engine shaft, being used only to convey the water from the deep workings to the adit level, and the other, the whim-shaft, to raise the ores to the surface. The two shafts are in these cases close together, and are united at convenient distances by short cross-cuts. It is always of importance to sink a shaft in such a way as to communicate directly with as many as possible of the lodes worked in a mine when, as is usually the case, several veins occur running in the same direction, and at no great distance from one another. In the Fowey Consols mine in Cornwall as many as thirteen lodes are worked, and they are so near each other that one shaft (the UNION) cuts through five of the lodes, and by means of a cross-cut at the sixty-fathom level, communicates with all the rest. The workings on different lodes are connected with each other by means of cross-cuts, so that the ores may be engines, in 1837, amounted to about thirty-seven millions of tons, and the aver- age number of engines at work was about seventy. The average discharge per minute in the Fowey Consols mine in the same year was fourteen hundred and seventy gallons, the greatest depth of the workings being one hundred and sixty fathoms (nine hundred and sixty feet) below the adit. The Dolcoath mine is much deeper (reaching two hundred and twelve fathoms below the deep adit), but the lower part is now, and has been for some time, filled with water. * The total amount of sinking in the Consolidated mines in Cornwall is stated by Mr. Taylor to amount to more than twelve miles of perpendicular depth, (in- cluding, of course, the winzes or underground shafts,) and the horizontal galleries extend to as much as forty miles in length. Parliamentary Report, 1835. Acci- dents in Mines. Qu. 1843. DEPTH OF SHAFTS. 293 brought to the shaft not only in the course of the lodes, but also at right-angles to their courses.* The lowest part of the engine-shaft, called the sump, is usually sunk a certain depth below the lowest workings, so that the drainage of the mine makes its way into it. It is, however, also important that each successive level should be separately drained in order that as little water as pos- sible may descend to these lower workings. The water raised is delivered at the adit-level, and so escapes at the natural drainage-level of the district. The depth to which shafts are sometimes sunk below the level of the surrounding country is sometimes very con- siderable. The Dolcoath mine, long celebrated for the depth and magnitude of its workings, reaches to more than 210 fathoms below the adit-level, which is itself thirty or more fathoms below some parts of the surface. The main shaft of the Fowey Consols is but little inferior, and there are several other mines both in Cornwall and elsewhere worked to a great depth, f * These cross-cuts must be understood as having no reference to cross courses, which are unprofitable veins traversing the lodes at right-angles. Great advan- tage, however, is sometimes obtained in mining, by observing the peculiar circum- stances connected with the traversing a lode by the cross courses. Sometimes the latter are scarcely touched, being only crossed at right-angles in working the lode ; but they are occasionally used to drive adits upon. The cross courses are also generally connected with faults, and sometimes they heave the lode, and bar the progress of the miner, while at other times they tend to keep out the water accumu- lated in the old workings of a neighbouring mine. It will be manifest that a con- siderable amount of practical knowledge must be required to enable the miner to venture on any speculations in a matter of so much importance, and that an accu- rate notion should be had of the true mechanical condition both of the lode and cross courses, before any undertaking, that depends for its success on their mutual in- fluence can be safely commenced. In such a case a false theory is worse than no theory at all ; and therefore it is that such speculations as those propounded by Mr. Evan Hopkins (see ante, p. 278), whose opinion as a practical miner is no doubt very valuable, are likely to be exceedingly mischievous, unless they are coun- teracted by more sober reasoning, and wider views of more numerous classes of facts in different mining districts. t The Tresavean, the deepest mine in Cornwall, is now worked at a depth of 294 UNDERGROUND WORK. In these cases the difficulty of mining is increased by the high temperature experienced in the workings,* but the veins can hardly be considered to exhibit any very decided and uniform change in the value or amount of their con- tents, although in some cases ores of different metals seem to abound most within certain particular limits of depth. The underground work of a mine depends chiefly upon the magnitude of the vein, and the value of the ore to be extracted. The vein once reached, either by the shaft or by the cross-cut carried horizontally from it, levels are driven at different depths (usually about ten fathoms, but depending greatly on the nature of the mining ground), and the whole horizontal section of the lode on each level is excavated by galleries. In many cases the lode not being more than a few feet in width, one such gallery is suffi- cient, and as it is only necessary to leave a passage wide enough to extract the ore, the levels at those places where the lode is narrow, or nipped in, are very narrow and con- fined. Where the lode is broader, and also rich, the open spaces are of course much larger, but there can scarcely be any rule in a thing so variable as a mineral vein, for the breadth of the parts worth working, though small and with little ore in some places, may be several feet across in others and extremely rich, or the vein may be thin and rich in one place, and broad and comparatively poor in upwards of three hundred fathoms ; and a machine has lately been erected there, by which the miners may be raised or lowered as much as two hundred and forty fathoms. The advantage of this machinery has already been greatly felt, and it must ultimately be introduced into all deep workings. * The increase of temperature in deep mines appears to vary according to some law which is not at present understood. At the depth of sixty fathoms the tem- perature is independent of atmospheric changes, and is about 60 Fah. At one hundred and thirty-two fathoms it is said to be 70, and at two hundred and forty fathoms, 80. According to Mr. Kenwood the increase becomes more rapid at greater depths. VENTILATION. 295 another; so that it may even be a question whether it is advisable to take that portion out at all. * There are, however, distinct methods of proceeding when it is required to extract very large masses of ore, and in those cases where the horizontal section is too large to be at once excavated, pillars are left to support a roof, and cross galleries are driven, intersecting one another. In order to avoid loss as much as possible, it is necessary in such cases to make the galleries lofty, and artificial sup- port is given to the roof by timbering : but accidents can hardly be avoided when this method is carried on to a great extent. Connected with these operations of mining, and so con- trived as to effect the required purpose in the best way, are the arrangements made for a proper supply of fresh air in the workings. The means of obtaining this are simple, where there is no evolution of noxious gas, and they con- sist chiefly of making a proper use of the numerous shafts, and of the communications effected from shaft to shaft by the different levels or galleries. When these communica- tions are properly made, currents are found to set in dif- ferent directions, varying probably according to the tem- perature of the atmosphere at the surface and the known increased temperature at considerable depths under ground, * De la Beche's Report, p. 561. Sir H. De la Beche adds, " These are mat- ters on which the chief agents decide according to their skill and judgment. It is usual in mines, particularly those worked on a large scale, and for a continuance, not to take out all the ore which could be immediately got at, if thought necessary, but to leave it here and there, to be worked as the general prospects of the mine may require, and to which the miners return if less ore is raised generally in the adventure than could be wished. The ores thus left in various places are called the eyes of the mine ; and when it may be necessary, in abandoning the mine, or from any pressing circumstances, to remove them, it is termed 'picking out the eyes of the mine." 1 In some mines these eyes are very valuable, and much skill and judgment is employed in so arranging the workings that a general good supply of ores may be obtained." 296 LOCAL NAMES OF VEINS. and it is rare that any mechanical means are resorted to for ventilating the mine, except in such cases as where a level is in progress to communicate with a shaft. Generally speaking, the air becomes vitiated to such an extent that candles cease to burn brightly, long before it is sufficiently bad to destroy life ; and, in fact, it is so impossible to con- tinue to work a mine in this state that accidents rarely happen. The veins of copper and tin, common in Cornwall, are for the most part not sufficiently thick to require any ex- traordinary method to be employed in extracting the mine- ral riches, but timbering is necessary to avoid the danger that would arise from the sinking in of the upper side of the vein.* In Derbyshire, and Alston Moor, however, whence the chief supplies of lead ore in England are ob- tained, the veins traversing the mountain limestone swell out and become productive chiefly or entirely in one bed of limestone, -f- and they there attain so great a thickness as to admit of being extracted by methods very different from those necessary to be resorted to in the Cornish mines. There are certain local names J given to peculiar forms of mineral veins in the north of England, to which I have already alluded, but there are others which must be now explained, while referring to the mining operations of the district. The most common of these veins is the raize vein, which is a vertical crack or fissure, or rather a group of such fissures parallel to each other, and frequently crossed * The quantity of timber used annually in the Cornish and Devon mines is very considerable, and consists almost entirely of Norwegian pine. Sir Charles Lemon having counted the rings of annual growth on several of the trees, considers that the average age of the timber employed in the Cornish mines is about one hun- dred and twenty years, and that it would require one hundred and forty square miles of Norwegian forest to aiford a supply for these mines. De la Beche's Re- port, ante tit. p. 573. t See ante, p. 253. + See page 248. HARDNESS OF ROCKS. 297 at right-angles by small pipe veins ; these pipe veins, the most important to our present purpose, are, in fact, hori- zontal expansions of the vein between certain beds of lime- stone, and are filled with the mineral matter which forms the matrix of the ore (barytes, fluor spar, calc spar, &c.) The appearance of one of the larger pipe veins is very curious, the vein being only rich where it expands on entering a particular bed of limestone. In the Alston Moor district there are many instances of this kind in the lead mines, and others are known in which rich ores of iron are worked, the masses of mineral substance being so extensive as to fill expansions of a vein which when exca- vated leave vast subterraneous caverns. In order to obtain the ore from the vein, and break it into masses of convenient size, many processes have been formerly employed, which have almost all given way to that of blasting with gunpowder. By the Saxon Geologist, Werner, rocks were divided into five classes, according to their degree of hardness, the first being sandy and fri- able, and capable of being removed with the spade, and the second including those rocks of moderate hardness, such as coal, the oolitic limestones, gypsum, shales, and slates, which require to be dislodged with the pick and removed in masses by the aid of levers and simple machinery. The third class of rocks includes those which are harder, but still not so hard as to strike fire with flint, and they may be removed partly by blasting, but chiefly with common picks, levers, and such simple machines. The fourth and fifth classes comprise rocks both hard and tough, and also those which are splintery, and they cannot be at all touched except with blasting, and even then sometimes scarcely repay the trouble and expense of working. The ancients, before the use of gunpowder was known, em- 298 BLASTING. ployed fire to fracture these rocks, and in some of the mines, both in Saxony and Hungary, this custom is still con- tinued ; a large rectangular box containing fire being placed before the naked surface of the rock until it is sufficiently heated, and then water being thrown upon the heated portion to crack and fracture it, and allow the workmen to remove it with the hammer, pickaxe, and other instruments. The employment of gunpowder in mines dates as far back as 1632, and since that time the labour of extract- ing the mineral produce in the great majority of mines has been very considerably reduced. The powder acts by the sudden and violent liberation of a quantity of gas, amount- ing, when the gas is incandescent, to between four and six thousand times the original volume of the powder; and the expansive force thus created is of the most active and ener- getic kind, and is especially useful in subterraneous works. The method of using this great, and, in mining opera- tions, most manageable power, consists in piercing a hole in the solid rock in places where the escape of the liberated gases is impossible without fracturing the rock itself. A cylindrical hole being thus formed, a charge of powder is introduced, varying of course with the nature of the rock and the magnitude of the work to be done ; and the charge being fired by a train of powder or a fuse, the miner has time to get out of danger before the explosion takes place. The process of blasting, in spite of the greatest care on the part of the miner, has often been the cause of fearful accidents, and these must continue so long as the old system of firing is adhered to ; but the danger is now hap- pily removed by the invention of a safety-fuse, introduced of late years, and at the present time, I believe, used in nearly all the mines of Cornwall. SAFETY-FUSE. 299 This fuse possesses three great advantages : First, that of certainty, and this is the same whether the ground be wet or dry ; secondly, that of safety : in one instance alone in the Kingstown Harbour, nearly 75,000 Ibs. weight of pow- der having been fired by this means since 1833 without a single accident, and numerous other similar examples being on record ; and, thirdly, that of economy, since the quan- tity of gunpowder saved repays the expense of the fuse. It is, indeed, so cheap, that it is no longer worth the while of the miners to make the common fuse when the safety- fuse has been once introduced. The fuse is about one fifth of an inch in diameter ; it has the appearance of a varnished cord, and burns slowly at the rate of eighteen inches per minute. By its means the charge may readily be lodged at any required depth in the rock, and any number of shots may be simultaneously fired. It has also the advantage of perfect simplicity, being more easily applied than any other process. Before the application of the safety-fuse several improve- ments had, indeed, been suggested, and, amongst the rest, the substitution of a copper needle instead of an iron rod to be inserted during the tamping or plugging the hole, and after the withdrawal of which the communication was made for firing the charge, and Mr. R. Were Fox had invented a contrivance, by which this dangerous mode of tamping or ramming in fragments of loose rock might be avoided. By the use of the safety-fuse, and with proper care in its application, scarcely any danger now remains.* The last operation connected with mining that I shall * I have dwelt at some length on this subject, and I would hope that the con- trivance I have alluded to, (and which is patented by Messrs. Bickford, Smith, and Davey, of Camborne, Cornwall,) may attract the notice of such practical miners as have not yet availed themselves of its advantages. I make no apology 300 RAISING THE ORE. allude to in this chapter, is that of bringing the ore to the surface, which I shall consider only so far as the mechanical contrivances required are connected with the general work- ing of the mine. After the ore has been detached from its matrix, it is necessary, of course, that it should be transported, in the most convenient way, to the bottom of the shaft, up which it is to be brought to the surface ; and in those cases in which the quantity of metal is small compared with that of the stone to which it is attached, and where the metal is not one of great intrinsic value, this becomes a matter of very considerable importance, and adds greatly in exten- sive mines to the expense of working. To diminish this for pressing strongly on their attention an invention which has already exhibited such important results in preventing the loss of human life. Some idea may be formed of the extent to which blasting is carried in mining operations, when it is known that as much as three hundred tons weight of powder is used annually, in Cornwall only, for this purpose. I also subjoin a table of considerable interest with reference to this subject, published in M. Burat's *' Geo- logic appliquee," p. 232. Result of blasting in the mines of Saxony and Bohemia, in galleries of the or- dinary dimensions per cubic metre : Quantity Hours Dimensions of of of Powder. Work. Gallery. Compact quartz, and quartz vein-stone, . 6'80 kil. 210 1.90x 1'20 metres. Very hard and tough gneiss, . . 4'64 171 2* Xl" Silver ore in a hard vein- stone of gneiss, i cemented by quartz paste, . . 5 3>l Ditto in a vein with clayey salbandes, . 2-20 111 2-10 X 0'85 Ditto in a vein of gneiss, cemented by ar- } gillaceous paste, .... j 1'30 66 2'47Xl' Ditto in a smaller vein, not gneissic, . 0'82 39 2*47 X 1'47 It will be understood, however, that, independently of the hardness of the rock, us crystallographical condition, and the nature of the cleavage it possesses, have a very great influence on the result. I have not thought it necessary to reduce these measurements to the English standard, because their chief value arises from the proportions that obtain. The following, however, are the values of the French measures : 1 metre = 1'0936 yards. 1 kilogram = 2*2055 Ibs. avoirdupois. RAISING THE ORE. 301 expense as much as possible, tramroads are now commonly used, and the dimensions of the waggons, or corves (from the German korb, a basket,) very carefully calculated ; but in many mines, more especially those in South America, human labour is still employed, men, and even women, carrying on their heads heavy weights up the numerous and steep ladders that communicate with the upper ground. In France and Germany, and in our own country, human labour is also employed, although chiefly in propelling, or drawing along underground galleries, the loaded waggons charged with the mineral produce of the mine. Great improvement has been effected of late years in the facility of transporting the ores underground, by the intro- duction of such small tramroads and waggons, instead of the old practice of wheelbarrows and planks ; and the saving of expense thus effected is very great, amounting, in fact, to one half the former cost. Many extensive mines are pro- vided with miles of this subterraneous railroad, and the ad- vantage is greater, because for the most part there is a slight descent from the workings to the bottom of the shaft, to allow of a more complete system of drainage than could otherwise be attained. The ores are usually lifted by machinery from the bottom of the shaft to the surface, and in all extensive mining ope- rations this machinery (the whim) is worked by steam- power ; but although steam- whims are now common, horse- power is still used to some extent. The quantity wound up at one time varies, but sometimes amounts to half a ton, or more. In a very few instances inclined planes assist in raising the ore, but it is only under peculiar circum- stances that they can be used with advantage. 302 CHAPTER V. ON THE PREPARATION OP ORES, AND THE GENERAL STATISTICS OF MINING IN DIFFERENT COUNTRIES. THE various processes by which metallic ores, after heing brought to the surface, are prepared, and reduced to the condition of pure metal or to a marketable form, must necessarily depend so much on the particular ores ex- tracted, on their chemical and mineralogical condition, and even on the mechanical condition in which they are found, that each different class requires, to a certain extent, a special description. I shall devote the present chapter to a consideration of the methods of reducing the ores of greatest economical importance, alluding, as occasion may seem to admit, to the statistical history of the mining districts in which they occur. Copper, of which the ores are chiefly met with in Corn- wall, is, next to iron, (of which I shall speak hereafter,) the most important and valuable of the metals found in Eng- land ; and as it is usually associated with tin in the mines in which it occurs most abundantly, I shall first speak of these two metals, of which the quantity annually obtained exceeds in value a million-and-a-half sterling.* Lead and zinc, the most important metals in England, next to iron and copper, will be afterwards considered with reference to the mines in Derbyshire and Yorkshire. * The following table will serve to give a general idea of the relative abun- ORES OF COPPER. 303 The chief ore of copper found in the south-west of Eng- land is the bisulphuret, or that which is called copper pyrites.* It contains, when pure, nearly equal parts of sulphur, copper, and iron, but in the lodes is often mixed up with other substances, such as sulphuret of zinc, iron and arsenical pyrites, quartz, chlorite, and other minerals, so that, although considerable masses of the pure ore are seen occasionally, it is usually so much mixed as to require dressing previous to sale. Its average price in 1838, when prepared for sale, was 5?. 1 7s. 6d. per ton of 21 cwt. The next important Cornish copper ore is the sulphuret, or grey ore of the miners, and it contains more than 77 per cent, of copper, 20 per cent, of sulphur, and a very little iron. Many variable compounds, however, pass with the dance and value of the mineral produce obtained from the different countries in Europe. It is chiefly deduced from M. Burat's work, already quoted. 1 Proportionate 1 produce. i 1 9 S 5 i 1 in , Value in ^Vs sterling. British Isles . 1000 Tons 3600 Tons. 12,000 Tons. Tons. 2,000 Tons. 46,000 Tons. 1,350,000 Ibs. 6,000 Ibs. i7,6oo,ooot Russia and Poland 285 - 3,300 - 4,000 600 300,000 38,500 12,000 5,400,000 France . 250 - 80 - - 400 430,000 3,314 5,280,000 Austria 154 20 3,500 250 75 4,500 70,500 42,500 3,250 2,680,000 German Confederacy 143 300 2,000 650 - 8,000 70,000 5,350 60 2,580,000 Spain . 125 - 25 1,750 85 20,500 15,000 - 2,160,000 Sweden and Norway 123 65 1,240 300 40 85,000 10,350 4 2,160,000 Prussia . 111 540 - 500 6,000 70,000 10,000 1,960,000 Belgium 91 - - - 1,750 325 162,000 350 1,600,000 Tuscany, Elba, &c. 32 24,000 600,000 Piedmont, Switz- > erland, Savoy, &c. 5 27 - - - - 350 22,750 1,250 13 440,000 Denmark 20 700 12,000 360,000 This is probably much overrated. De la Beche's Report, ante tit. p. 590. 304 PREPARATION OF THE ORES OF COPPER. miners for this ore : it is extremely valuable, and, as well as the black ore (an almost pure oxide and containing nearly 80 per cent, of copper), is occasionally in sufficient abun- dance to increase very greatly the value of the produce of the mine in which it appears. Even so lately as at the end of the last century many of these rich ores were thrown away by the miners, their value not being known, and before the year 1700 copper ore seems to have been only obtained accidentally, and from mines worked for tin. The ores having been thrown into the places appointed for them, are broken by small hammers and divided into two heaps, one containing the good ore, and the other what are called leavings. These fragments are then passed through the crushing machines, in which the ore is crushed to the size required for carrying on the farther processes between iron or steel rollers, generally set in motion by water-power. As the crushed ore falls from the rollers it is received in a sieve, commonly inclined and made cylindrical, so that by turning round on its axis the larger pieces of ore slide down to the bottom, while the smaller pass through the wires of the sieve, and by these means the fragments which have not been sufficiently crushed are collected, and may be passed again through the rollers. The next process is called jigging, and is accomplished by putting the crushed ore into a rectangular chest, or tub, in which a sieve is suspended and immersed to a proper height in water. To this sieve a vibratory motion is com- municated, so that the particles in it arrange themselves according to their relative specific gravities ; the metallic particles being the heaviest are thus carried to the lower part of the sieve, and the rest may be removed, and if thought sufficiently rich, be jigged over again. The richer CORNISH COPPER ORES. 305 portions are then picked out by hand, a work performed by women and children, and the poorer parts are passed to the stamping-machine, where, after being pounded, the metallic portions are separated, still "by the aid of the water, from the other parts. By the processes of picking, crushing in various manners, jigging, and washing, the ore is at length rendered saleable, and it is then usually exported to Swansea in South Wales, there to be smelted with the copper ores from other parts of the United Kingdom, and from many foreign countries, taken to the same place. In the year 1838 nearly two hundred thousand tons of copper ore were there smelted. The quantity of copper ore raised in Cornwall is very considerable, and has been steadily increasing on the average of a number of years. In 1775, the quantity did not amount to 3600 tons, and its value was 192,000. At the commencement of the present century it had increased to upwards of 5000 tons, and its value then was nearly half a million of pounds sterling. A quarter of a century later the supply was upwards of 8000 tons, and its value reached 750,000^., while in 1838, 11,527 tons of copper, obtained from 145,688 tons of ore, were raised, and the value of the metal was 857,779. Of the Cornish mines, the Consolidated mines are those from which the greatest amount of profit is obtained from copper mining. In addi- tion to the quantities mentioned above, about six thousand tons of ore, producing 527 tons of metal, were raised from the Devonshire mines in 1838. The ore from which is derived nearly, if not quite, all the tin obtained from the Cornish mines, is the per-oxide, and it occurs of variable degrees of purity, sometimes crystalline and at others mixed with much earthy matter. Except when mixed with wolfram (the tungstate of iron and VOL. II. X 306 ORES OF TIN. STAMPING. BUBBLING. manganese) it is readily separable from earthy impurities owing to its great specific gravity, but the presence of wol- fram not allowing this process to be used, is considered highly injurious to a tin-lode. The mechanical act of separating the tin ore from mine- rals associated with it (technically called vanning) is effected with great dexterity by the Cornish miners. It is done by placing a small portion of pulverised ore towards the end of a pointed shovel, and then, by dexterously dipping it in the water and agitating it by a peculiar motion of the arms and wrists, it arranges itself according to the relative specific gravity of its component parts. But the operation of vanning is subsequent to the first processes that are gone through after the ore is obtained from the matrix or separated from the gravel amongst which it is found. The ore, however obtained, is carried first of all to the stamping-mill (usually worked by steam-power) to be crushed and pulverised under water. It is then car- ried, mechanically suspended in running water, into a pit, where, arranging itself according to its specific gravity, the heaviest part is accumulated at the head. The more slimy ore passing to the lower end, a further deposit is made in a round pit at the end of the first or rectangular one, and the matter still remaining suspended in the water is allowed to be carried away as worthless. In this state the heavier mass in the first pits is called the crop, and the other the slime. The ore being thus separated, the crop is taken to a large pit, termed a huddle (about 7 feet long, 2^ wide, by 2 deep), and a man standing in this pit arranges the pulverised ore upon an inclined wooden frame, in small ridges parallel to the run of some water which is allowed to enter the frame with regulated velocity. In this way, and oy a few simple contrivances, the ore is divided into four heaps, which differ- ORES OP TIN. ROASTING. 307 ing in the rate at which they sink, differ in the same way in relative value. After this, the heavier portions are again subjected to a similar washing in a large vat, and of the rest, all but the lightest are huddled once more, or are at once separated as leavings. The method of separation is in all cases the same, the greater specific gravity of the ore being the only means employed to separate those which are metallic from the mere earthy particles. After various operations of this kind,* and when the ore has been exposed to washing till but little earthy matter remains, it is usually roasted in furnaces, which contain about seven cwt. of ore, and while undergoing this process is stirred about until it ceases to exhibit bright sparks or emit whitish fumes. In this way it is freed from various impurities, such as arsenic, sulphuret of copper, common iron pyrites, &c., which are driven off in the state of vapour, and it is afterwards again washed and sifted, and reduced to the state called black tin, in which it is saleable, and contains a very large per centage of pure metal. The total annual produce of the Cornish mines varies considerably, but it may perhaps average about seven thousand tons of black tin, the value of which is something more than 350,000^. The further processes by which it is reduced to the metallic state and afterwards refined, belong strictly to the art of metallurgy, and although not entirely excluded from considerations of practical Geology, hardly admit of description in the limited space I am enabled to devote to the subject. The ores of copper and tin, of which the method of treatment has been in some measure described, belong to that class which may be called disseminated (in German, eingesprengt) and in both cases the metalliferous particles * These are minutely described in Sir H. de la Beche's Report, p. 577. x 2 308 ORES OF LEAD. being comparatively small, they can be prepared for smelt- ing merely by stamping (or pounding) and washing ; the metalliferous particles being heavier, and separating them- selves from the other minerals by the proper application of a current of water. It will, however, readily be understood that the shape of the particles may have a considerable in- fluence on the applicability of this process, and in fact it is only when the metallic ore occurs, more or less, in the form of grains, that the separation by washing is advanta- geous, while, on the other hand, when it exists in the shape of thin leafy or scale-like particles, these metallic particles, instead of sinking more rapidly, float longer than the non- metallic substances with which they are mixed. The principal lead ores in England are those worked in the north of Derbyshire, in the county of Flintshire in North Wales, and in the neighbourhood of Alston Moor in Cumberland, and the veins containing the ore have been already alluded to as offering some singular and interest- ing peculiarities of form. From these veins the ore of lead called galena (a rich sulphuret) and ores of zinc (calamine and blende) are obtained in considerable abundance, and the lead is usually accompanied by a small per centage of silver, varying from two to about four-and-twenty ounces per ton. The galena is principally cubical, but sometimes compact, steel-grained, and accompanied by ores of antimony, and these two ores are frequently blended together and inti- mately mixed with the spar or vein-stone, locally called rider. Another ore of lead also occurs, not crystalline, but in plates presenting a smooth surface, and usually adhering to sulphate of barytes : it is called slickensides,* and the sulphate of barytes to which it is attached possesses the pecu- * The smooth striated surface of a fault is also in some cases designated by this name. ORES OF LEAD. 309 liar property of spontaneous explosion when first laid bare. The explosion usually takes place ten or fifteen minutes after a small incision or cavity is made with the point of the pick, and considerable masses of ore and vein-stone are often detached by it. In Derbyshire and the north of England, as in Cornwall, the working of mines is subject to special laws, mostly of very ancient date, but in the northern district these laws only apply to a part, and even a small part of the whole mining country, that namely, which is known as " the king's field," in the north of Derbyshire. The ores of lead often occur in pieces so large that they do not require to be separated from the veinstone by the processes of stamping and washing ; they are then called pure ores, and the most simple preparation is sufficient to prepare them for the smelting-furnace. When the ore has been picked and so far prepared, it is first roasted or heated in a reverberatory furnace,* and in this way the sulphur * A reverberatory furnace (see the annexed diagram) is a furnace in which intense heat is produced by a flame which, while passing through the furnace, reverberates from the roof over the substance to be fused, the draught being created M Scale of feet. SECTION OF A REVERBERATORY FURNACE. by means of a lofty chimney. The form commonly used in roasting the lead and other ores of Derbyshire, is shewn in the accompanying diagram, where A represents the fire-place, and the flame is forced to pass round over the hearth be- 310 ORES OF LEAD AND SILVER, is partially expelled, and the ore rendered more easily re- ducible. The lead which remains after the operation of roasting is in an oxidated state, and is then mixed with the necessary quantity of coke, charcoal, or peat, and reduced by smelting in a small blast-furnace of a peculiar kind. By the appli- cation of heat and the inflammable matter with which it is mixed the metallic oxide is decomposed, and the oxygen, combining with the carbon, flies off in the form of carbonic acid gas, while the lead is reduced to the metallic state, and sinks to the bottom of the furnace. The produce from the finer ores amounts to 70 or 80 per cent. Almost all the varieties of galena, or lead-glance, contain a greater or less proportion of silver, * and it is often found worth while to separate the silver by taking advantage of the difference of oxidability of the two metals. This is done by exposing the argentiferous lead to a strong blast of air, at a high temperature, in a furnace so contrived as to allow the litharge, (protoxide of lead), to separate imme- diately, while a fresh supply of lead is constantly introduced as the operation proceeds. The lead thus becomes rapidly fore proceeding to the chimney. In a blast-furnace the fire is maintained by an artificial stream of compressed air, and the fuel is brought into immediate contact with the substance to be acted upon. * The Cornish ores contain a larger proportion of silver than those of Derby- shire and the north of England, but the method of treatment is the same, or very nearly so. In one mine, near Truro, as much as one hundred ounces of silver per ton of lead was obtained in 1720, and this mine was re-opened in 1814, and then yielded at the rate of seventy ounces. But the Beer Alston mines in Devonshire are the most remarkable for their riches in this respect ; and the two lodes near Beer Alston have produced large quantities of argentiferous galena, often containing from eighty to one hundred and twenty ounces of silver per ton of lead. Accord- ing to Mr. Hitchings, the greatest proportion which occurred in any one part was one hundred and forty ounces. Independently of these argentiferous ores of lead, native silver, ruby and grey silver ores, and the black sulphuret, have been raised from various mines in Cornwall. Gold is also occasionally found ; but this is in the tin stream- works. 0>RES OF ZINC. 311 converted into the protoxide (litharge), while the silver forms a cake, readily separated at the end of the process. The litharge is reduced to the metallic state again in a rever- beratory furnace, and the total loss does not amount to more than about one sixteenth part of the original quantity of metal. Next to lead, zinc must be considered as the most impor- tant metal obtained from the Derbyshire mines, and the discovery that this metal is malleable at a temperature of 300 Fahrenheit, and can then be worked to any shape with great facility, has caused it to replace lead for many purposes, in which its hardness and other useful qualities render it superior. The ores of zinc commonly worked are two, blende (the Hack jack of the English miners) and cala- mine, the latter of which has long been known as an impor- tant constituent of brass. Blende is a sulphuret of zinc, and, together with cala- mine, is found associated with lead ore in the veins of the mountain limestone of Derbyshire, and Alston Moor. The latter ore (calamine) is also found in the magnesian limestone, and has been worked in the Mendip Hills, near Bristol, from a considerable number of small excavations, the ores consisting partly of galena, and being mixed also with a considerable proportion of carbonate of lime In the north of England the ores of zinc sometimes accompany lead ores in the same veins, but they are also met with in separate veins, while in one instance of a rich vein of lead, worked at Holywell, in Flintshire, calamine is found only in the east and west ramifications of the vein (whose principal direction is north and south), while blende abounds in the mine, and occurs indifferently in all parts of it. The ores of zinc, like those of lead, after being coarsely 312 ZINC MANGANESE. pounded, are usually calcined in reverberatory furnaces, but are sometimes burnt without undergoing this process. In the latter case the ore is first broken into fragments about the size of a pigeon's egg, and is mixed with an equal quan- tity of coal. In reducing the calcined ores of zinc to the metallic state, rectangular or round furnaces, containing a number of crucibles, are commonly employed. The crucibles themselves are made of clay, and are pierced at the bottom with a hole plugged with a piece of wood, the carbon of which assists the running of the metal when the fire is applied. The crucibles containing the ore are introduced at the side of the furnace through apertures, which are afterwards filled up with fire-brick. For about two hours the crucibles are left in this state and without any co^er, but then, when the appearance of a blue flame indicates that the reduction of the metal has commenced, the covers are put on, and vessels, called condensers, are placed to re- ceive the metal. The sole care of the workmen now is to keep the fire active, and remove the condensers when they are full, replacing them by others. The fire is not allowed to diminish, but successive charges of ore replace those from which the metal has been obtained, and the operation goes on continuously. The zinc is obtained in the form of small drops or grains, or fine powder, mingled with an oxide of the metal. This is melted afterwards in an iron cauldron, and run into moulds. Manganese is a metal the consumption of which has very much increased of late years, and its ores must now be considered to form an important part of the mineral riches of our country. The value of the manganese ex- ported from Cornwall in 1837, amounted to 40,000., and ORES OF IRON. 313 a very considerable portion of the whole quantity is em- ployed in the manufacture of the chloride of lime, the solution of which is used as a bleaching liquid. The mines from which manganese ore (chiefly the grey or black oxide) is obtained, are mostly shallow, and some- times even worked at the surface, and there is probably no instance in which any important machinery is required, or indeed, anything more than a horsewhim to be employed in raising the ore. The metal itself not being made use of in the arts, there is no need that I should detain the reader with an account of the difficult processes by which the chemist is enabled to reduce it. Besides being found in great abundance in Cornwall, the grey oxide of manganese occurs in all parts of Europe and in America, and is usually associated with iron ores. The ores of many other metals are found occasionally in the metalliferous veins of Great Britain, and amongst them may be mentioned cobalt, bismuth, nickel,* and arsenic, all occurring in Cornwall, and generally accompanying the ores of copper, but none of them very abundant. Anti- mony is much less rare, and occurs in the native state, accompanying lead, and combined in definite proportions with sulphur. Iron is everywhere distributed, and very rich hoematite, and some other ores of iron, occupy an enormously thick vein which traverses the mountain lime- stone at Ulverstone, in Lancashire, and veins of smaller importance in Cumberland and Devonshire. But the ores of iron, which from their abundance, and from the cir- cumstances of their occurring associated with coal and * It is a singular fact, that nickel is usually associated with iron in those meteoric stones., as they are called, which are found occasionally in all parts of the earth. Enormous masses of iron, combined with nickel, are also found scattered over the surface of the ground in Mexico. 314 GERMAN MINES. limestone, are of the greatest economical importance, and supply almost the whole of that vast quantity annually consumed in England, are not deposited in veins but are regularly bedded, and will come under our notice in another chapter. It is not necessary that I should detain the reader here with any detailed account of the methods employed on the Continent of Europe in obtaining those metals found abundantly in our own island. The different mining districts of Germany, indeed, and more especially Saxony and the Hartz, have for ages been celebrated for the extent, and the perfection of economic arrangement, with which their mining operations have been carried on, but the me- thods employed do not differ sufficiently from those already detailed, to admit of any popular statement. Much of the manipulation in metallurgy must depend on the tact and quickness with which the manager of a mining property can avail himself of the constantly varying circumstances of the ore and the mineral vein he is working ; and a due or improper admixture of ores may often make the differ- ence between success and failure. Such knowledge as this can only be the result of expe- rience, and is not to be attained without careful attention and minute observation ; but although a familiar acquaint- ance with the principles of Geology must be extremely valuable even to the metallurgist, it would be unreasonable to expect in a general account of Geological facts any detailed information on a subject so technical. Of the metalliferous ores not found so abundantly in England as to be worth working on their own account, the chief are those of silver and gold, which at present are principally obtained from the Continent of America and from Asiatic Russia ; and those of mercury, long worked, SOUTH AMERICAN SILVER MINES. 315 and still very abundantly found in Spain, and also in the mines of Idria, in Carinthia. Of the precious metals, I have already mentioned silver as occurring in our own country to some extent, but until the discovery of America, a very large proportion of the whole supply of Europe was obtained from the celebrated mines of Saxony. Russia has always contributed a consi- derable amount of gold, and also a large quantity of silver, and there can be no doubt that both metals have found their way to Europe from various parts of Asia, where, more especially in the East, they appear to be sufficiently abundant. In describing the methods of obtaining silver, I shall chiefly allude to those pursued in the celebrated Mexican and Peruvian mines, and it ought to be distinctly under- stood that, notwithstanding the very large quantity of the precious metals obtained from the mining districts of South America, the ores are not on the average richer than those of Freiberg, of Hungary, or of Transylvania. It is not, therefore^ (as is generally supposed,) from the intrinsic value of the minerals, but rather from their great abundance and the facility of working them, that the mines of America are to be distinguished from those of Europe ; the mean wealth, even of the richer veins, not being greater than four ounces of silver to the hundred- weight of ore extracted, while many districts of Saxony have, at fortunate periods, yielded ten and even fifteen ounces, and have seldom averaged much below three. The mines of New Spain, the central group of which comprise three mining districts, including an area of about seventeen hundred square leagues, are probably the most abundantly supplied with the precious metals of any in the world, and of the three districts, the most southern 316 MINES OF NEW SPAIN, of the group that of Guanaxuato is as remarkable for the gigantic labours of man in the bowels of the mountains, as for its vast natural wealth. A group of porphyritic hills, partly arid, and partly covered with the evergreen oak and the strawberry tree, rises on the ridge of one of the mountains of the Cor- dilleras, from a part of the great central table-land of Mexico. The absolute height of the summits of these mountains ranges from 9000 to 9500 feet above the sea- level, but as the neighbouring plain is nearly 6000 feet above the sea, they appear only as insignificant hills to the eye of the traveller accustomed to the lofty mountains of the Southern Continent. The famous vein of Guanaxuato, the veta madre, crosses the southern slope of this porphy- ritic range, and the outcrop of the vein runs from south- east to north-west. The quantity of the precious metals obtained annually from this vein on the average of a number of years, amounts to nearly three hundred thousand pounds weight of silver, and eight hundred pounds of gold, nearly double the average of the more celebrated mines of Potosi."* This vein it has already been stated, has been worked for a length of upwards of six miles, although the silver has been extracted only on a line of about one mile and a half. Its direction is stated by Humboldt to be N. 52 W.,-f- and its inclination from the vertical 45 or 48 to the south-west. It has been doubted whether this great mass of metalliferous ore could properly be called a vein, as it seems to have the same direction and dip as the * The mountain of Potosi has, however, furnished since its discovery in 1545 to the beginning of the present century, at least as much silver as was worth 235 millions of pounds sterling, although at the present day the quantity extracted is comparatively very small, and the proportion of metal only about 1 in 2500. f Political Essay, ante cit. vol. iii. p. 185. MINES OP NEW SPAIN. 31 7 clay-slate in which it occurs; but in spite of this remarkable coincidence of direction of the crevice and the rock fractured, it appears to be a true vein, since towards the south it is known to run through porphyritic mountains, and throughout that part which has been worked its rich- ness is found to be invariably greatest where the direction of the numerous ravines of the valleys which it crosses, and of the slope of the mountains, has been parallel to that of the veins. It is found also to divide into branches, to vary very greatly and capriciously in thickness, and to contain druses abounding with amethyst and other crystals. There seems to be a certain moderate depth at which the greatest riches occur, and this is stated by Humboldt to be between six and seven thousand feet above the level of the sea. The mechanical contrivances resorted to, and the methods of working these mines generally, were at an ex- tremely low ebb at the commencement of the present cen- tury, and although the ores are incredibly abundant, they are at the same time so poor, as not to average more than four ounces of silver per cwt. of ore. Notwith- standing this, the whole of the ore, at the period alluded to, was conveyed to the surface by human labour, the native Indians carrying a weight of from 240 to 380lbs., exposed to a temperature of from 70 to 80 Fah. for a space of six hours, and during this time ascending and descending several thousands of steps in pits having an inclination of 45. The works too, at that time, rarely communicated with one another, the drainage was in the worst possible state, and was effected by mules, who raised the water in bags, while a considerable proportion of the water was allowed to drain from the upper works to the deepest part of the mine. 318 AMALGAMATION OF SILVER ORES. Nor was the miner better informed or more economical in his work. The quantity of powder used in blasting was much more than necessary, and all the arrangements seem to have been conducted in the most careless and unecono- mical manner. Doubtless all these matters have been greatly improved within the last quarter of a century, and the works are now conducted with care and attention, and with economy, but no general account of the improvements has yet been recorded, nor is it very likely that another Humboldt will soon be found to narrate with accurate minuteness the details of all the important works now proceeding in this interesting district. The methods of preparing the ores of silver and gold differ according to the process by which it is intended to obtain the metal. A considerable proportion of the ore is destined for the process of amalgamation, and in this case it is triturated in powerful mills (generally in a crude or raw state, sometimes dried, and sometimes, though rarely, roasted in large heaps out of doors). After undergoing tri~ turation, which is effected if possible by means of hydraulic wheels, but more usually by mules, the ore is sifted through a hide sieve, and the coarser parts are returned to be again stamped, while the finer portions are reduced to a very fine powder under blocks of hard stone, dragged round horizon- tally in a circular pit. A great number of these mills are attached to works of any importance, and even the smaller ones are provided with twelve or fifteen of them ranged in a row, and each grinding from ten to twelve cwt. of ore daily. A small quantity of quicksilver is added to such silver ores as have traces of gold, because mercury having a greater affinity for gold than silver, a fluid auriferous amalgam is thus obtained which contains but little silver. The amalgamation generally takes place in a yard care- AMALGAMATION OF SILVER ORES. 319 fully paved and well enclosed by substantial walls. In this yard the heaps of ore to be amalgamated are thrown, each heap containing from fifteen to thirty-five cwt., and forty or fifty such being exposed to the open air in a damp state. The heaps are then prepared by mixing with them about six per cent, of salt as soon as they have received due con- sistency, and after this mixture they are left undisturbed for a few days; then follows the admixture of metallic salts, technically called, " magistral " (regulus). Various mixtures are made use of for this purpose, the oxides and sulphurets of copper and iron being the chief elements. Formerly, gently roasted copper pyrites, either with or without iron, and muriate of soda, were alone made use of, but of late years a protoxide of copper has been introduced, and is found advantageous. The quantity of this magis- tral to be mixed with the ores differs greatly according to their quality, some needing six per cent, while others require only one. It is first strewed on the heap, and soon afterwards the first portion of quicksilver is added, being sprinkled on by passing it through a linen cloth. It is then triturated with very great care from time to time, much attention being paid to the due consistency of the paste, and continued examination being made, to see whether the incorporation, which consists in simultaneous oxidation, formation of chloride, and attraction of the silver by the mercury, is duly going on. If it be too lively, it can be checked by the addition of lime, and if too tardy, a further addition of magistral will quicken it. The process lasts a very variable time, depending partly on the climate and partly on the nature of the ores, so that sometimes it requires not more than three weeks, and some- times as much as two months. About six pounds weight 320 RUSSIAN GOLD ORES. of quicksilver is allowed for each pound of silver expected, and the loss of mercury is very considerable, amounting to about one and a half times the weight of the silver ob- tained. The amalgam is reduced and the silver separated by the process of distillation.* The quantity of silver produced from the Mexican mines in 110 years, ending with the first year of the present cen- tury, was something more than ninety-eight millions of pounds troy, and the total value of the gold and silver together, produced from 1689 to 1803, has been calculated at about 285 millions of pounds sterling. Since the com- mencement of the present century the quantity has been increasing, though not with any regularity. Before concluding my remarks on the precious metals, I must not omit to mention the greatly increasing importance of the Russian provinces of Siberia, with respect to gold ores. During the past fifteen years the supply of gold from that country has been gradually, but steadily and * The process of amalgamation is carried on in Saxony in a manner somewhat different from that described above. It is found that the amalgamation succeeds best when the proportion of silver is about seventy-five ounces in the ton ; and the ores are therefore selected so as to bring the whole as near this average as possible, regard, however, being had to the proportion of sulphur, which is ascertained by assaying the ore. As the combination with sulphur, and other substances, inter- feres with the amalgamation, the raw ore is first mixed with 10 per cent, of com- mon salt, and being then burnt, the sulphur becomes acidified in the furnace, the liberated acid combines with the base of the salt, forming sulphate of soda, and muriate of silver is formed by the union of the muriatic acid of the salt with that amount of silver in the ore not already in the metallic state. In this state the ore is reduced to an impalpable powder, and submitted to the action of mercury in barrels, which are so arranged as to revolve on their axes. The charge in each barrel consists of calcined ore, mercury, metallic iron, and water in certain proportions, and by constant friction during sixteen or eighteen hours the muriate of silver is decomposed by the iron, the silver combining with the mercury, while the sulphate of soda, muriate of iron, and other salts, are dis- solved in the water. The result is then filtered, and the amalgam subjected to the action of heat, which drives off the mercury, the silver remaining. Taylor's Records of Mining, p. 31. ORES OF MERCURY. 321 rapidly, increasing, so that while in 1830 the value of the metal obtained did not amount to 10,000?., in 1842 upwards of 30,000 pounds weight (troy) was obtained, the value of which would be nearly a million and a quarter of pounds sterling, and it is believed that the quantity was even greater in 1843. The greater part of this large supply is derived from washing the auriferous sands. Platina is a very remarkable metal, usually associated with gold in the mines of Russia and South America, and only found in the native state. It is the heaviest, the most difficult of fusion, the most ductile, and the most flexible metal. It occurs in small flat shining grains, and its colour is a light steel grey, approaching to that of silver, whence its name is derived (Plata, silver). It is extremely mal- leable, and like gold is only affected by nitro-muriatic acid. It welds like iron, and in this way is capable of being manufactured into cups, crucibles, and spoons for chemi- cal purposes, and small reflectors, for all which its peculiar qualities admirably adapt it. The chief source of the supply of Mercury is the extensive mine of Almaden, in Spain, which has been worked for upwards of two thousand years. Besides this, the mines of Idria have been resorted to from time to time, but there can be little doubt, from indications that have already appeared, that the importation of this metal from Europe will soon be quite unnecessary, and Mexico and Peru, instead of being dependant on the Old World for this metal, will soon be in a condition to supply it. The existence of veins containing ores of quicksilver has indeed long been known in South America, and one very remarkable mine, that of Huanca- velica, is worked at the height of 14,500 feet above the sea, the ore obtained being a rich cinnabar, (sulphuret of mer- cury,) and apparently existing in great abundance. VOL. II. Y 322 ORES OF MERCURY. The mines of Idria are scarcely less celebrated than those of Spain for the ores of mercury they contain, but the produce is by no means so valuable. Cinnabar is there also the principal ore, and it is distributed in various ways through the matrix, sometimes nearly pure and in small fragments, and sometimes appearing as a compact mineral of a deep red colour. Native mercury is found occasionally disseminated in the veinstone both there and in one or two mines of cinna- bar, near Obermoschel, in Rhenish Bavaria, not very far from the town of Bingen on the Rhine. These latter mines are also interesting as frequently containing good crystals of a native amalgam of mercury and silver. The usual method of reducing the ores of quicksilver is by distillation. The minerals brought out of the mine are broken up, and picked by women and children, and then in some places the richer ores are separately burnt, but it is more usual, and considered more economical, to mix the richer with the poorer ores, and expose the whole mass together to the action of heat in closed retorts, which also contain a certain proportion of limestone. The retorts, filled with the mixture of ore and limestone, are ranged to the number of twenty or more in recesses of a furnace, and heat being applied, each retort is made to communicate with a vessel of water, in which the vapours of the mercury are condensed. In the mines of Idria a diiferent method is adopted, the ores being there roasted in a kind of oven, and the vapour resulting from this operation passing into condensers, where the little drops of mercury collect, and are conducted into a porphyry vessel placed to receive them. Besides those which I have now described, and which are the metals chiefly used in the arts, there are a number of others, some of them valuable when mixed with other BISMUTH, NICKEL, ANTIMONY, ETC. 323 metals but of themselves rarely employed, while others are only known by their salts and oxides, and others again have not yet been applied to any practical use, and are only objects of interest to the chemist. Bismuth, Nickel, Antimony, and Arsenic are among the first of these metals. The next includes Sodium, Potassium, Calcium, Chromium, Cobalt and some others ; while Rho- dium, Iridium, Osmium, Palladium, Yttrium, Tungsten, Titanium, &c., complete the list. Bismuth is generally found native in veins of silver or cobalt ore, and it is readily obtained from these ores by processes in which advantage is taken of its extreme fusi- bility. It forms alloys with other metals. Nickel is a somewhat interesting metal, being always present in what are called " meteoric stones, 11 and becoming readily magnetic. It is usually mixed with arsenic in veins of lead and zinc. Nickel is an exceedingly brittle metal. Antimony, in the condition of a sulphuret, is found very frequently associated with the ores of lead, and is a metal of considerable importance, being used in the arts to some extent, especially in the manufacture of type-metal. It is also used in medicine. Arsenic is a metal of very frequent occurrence, and is found both pure, and in combination with other metals. Its presence may be known by the odour of garlic which it gives out when heated or struck with a hammer. With regard to the other metals. Cobalt is never found pure, but is mostly combined with arsenic and sulphur. Chrome, like cobalt, is best known as a pigment, communi- cating a green colour to porcelain, &c. Calcium, sodium, and potassium are the metallic bases of lime, soda, and potass, and are never found native. Ehodium, iridium, osmium, and palladium are extremely rare, and are only found alloying platina. Y 2 324 CHAPTER VI. ON THE METHODS OF OBTAINING MINERAL PRODUCE FROM BEDS INTERSTRATIFIED WITH THE REGULAR DEPOSITS WHICH FORM THE GREATER PART OF THE CRUST OF THE GLOBE. MINING FOR COAL. THOSE departments of mining which have been considered in the preceding chapters, have reference only to the metallic ores obtained from lodes or veins in fractured strata, the fissures so filled up being due to the action of subterraneous violence subsequent to the deposit of the strata. Such ores differ in this respect entirely from minerals which are regularly bedded, and which themselves interstratify with the limestones, the clays, and the sandstones, and help to make up the great series of rock formations ; and it will be found that this difference extends to the contrivances that are necessary in order to obtain the bedded minerals from the bowels of the earth. It results from the simple fact that the minerals in one case are bedded, and in the other are deposited in crevices in the fractured strata, that there should be a regularity existing in the former, and a uniformity of general charac- ter and appearance utterly unknown in the latter, and it cannot excite astonishment that the methods of underground working in the two cases differ most essentially. As, there- fore, in the former chapters I have described at some length QUANTITY OF COAL RAISED IN BRITAIN. 325 the successive processes by which metalliferous ores are extracted from mineral veins, brought to the surface of the earth, and there reduced to the metallic state, so now I shall speak of mines of another kind, from which minerals are obtained, (chiefly coal and iron,) which form actual beds, and an integral part of the crust of the earth. Nor are these minerals, of which I am about to speak, namely, coal and the ores of iron, to be considered of inferior importance among the mineral produce of Eng- land. If, indeed, the British Islands occupy, as they do, a most important place among mining countries for the value and extent of their mines of copper, tin, and lead, they are far more distinguished from the rest of the world by their unequalled riches in the more useful, if not more intrinsically valuable supplies which they contain of coal and iron ore. Notwithstanding the cheapness of the pro- duce of this kind, the value of the coal actually brought to the surface in England amounts annually to nearly ten millions of pounds sterling, and almost the whole of this is derived, although in unequal proportions, from the New- castle, the South Welsh, the Staffordshire, and the Scotch coal-fields. With regard to the first of these, the Newcastle coal- field, it is said that upwards of six millions of tons are there annually raised up out of the bowels of the earth, that 60,000 persons are employed in the mining operations, that fourteen hundred vessels are constantly engaged in conveying the coal (amounting to three millions of tons) required for the consumption of the metropolis only, and that the capital involved in simply conducting this trade amounts to several millions of pounds sterling. On the other hand, in the South Welsh and the ad- 326 ORIGIN OP COAL. joining coal-basins, the coal is chiefly used in the manu- facture of iron, and the smelting of copper and other metals. In 1839, more than half a million of tons of pig iron were made in the Forest of Dean, and nearly three hundred and fifty thousand tons in South Staf- fordshire. In the manufacture of this quantity, at least five millions of tons of coal were required, and another million of tons were during the same year exported. Compared with these numbers, the quantity of coal raised from the other fields will appear inconsiderable, but certainly not less than three millions of tons more are extracted from the mines in Scotland, from those distributed in various parts of England not before includ- ed, and from those in Ireland. We see, then, that at least fifteen millions of tons of coal are annually extracted from coal-mines in the British Islands, and are employed for the use of man. I regret to be obliged to add, that a quantity, supposed to amount to, at least, two millions of tons more, is during the same short period wantonly destroyed, in order to enhance the price of part of the remainder. It is not my intention to discuss in this place the vali- dity of the arguments that have been advanced in proof of the vegetable origin of coal. Something has been said on this subject, in treating of the fossils of the carboni- ferous system (vol. i. p, 346), and perhaps enough to con- vince the unprejudiced reader ; for if the actual discovery of organised structure and of vegetable tissue in the coal is not sufficient proof of its vegetable origin, it would not be easy to say what greater amount of evidence would produce conviction. But the condition of the vegetables, and the kind of vegetation imbedded, must still be con- sidered as doubtful questions, and it is not unlikely that COAL NOT UNIVERSALLY DISTRIBUTED. 327 in different localities, all the different modes that have been suggested may at some time or other have been brought into action. There are, however, two exceedingly important matters to be considered and understood before proceeding to the practical question of the method of working in coal- mines, and these matters themselves are both eminently practical, both strictly dependant on that class of phe- nomena studied by the Geologist, and both, therefore, proper to be discussed in this place, as connected with the Geology of practical mining. I allude to the frequent repetition, and as frequent loss, of the coal strata, by faults and dislocations, and to the fact, that those beds con- taining valuable fuel capable of being extracted and em- ployed for economical purposes, are only found in one formation, are even strictly confined to a certain part of that formation, so far as practical mining is concerned, and are confined to that formation, not only in our own country, but wherever extensive deposits of coal have hitherto been found in Europe.* This latter fact is one, the knowledge of which is * This is at least strictly true so far as regards bituminised vegetable matter developed to any extent in Europe, and capable of being used for economical purposes as fuel. Doubtless the lignites and imperfect coal worked at Brora, in the lower, and at Kimmeridge, in the upper oolitic strata, and the brown coal of Germany and Switzerland are capable of being burnt, but they do not form true coal ; and perhaps the most remarkable fact is, that these different beds exhibit scarcely any approach to the nature of true coal, so that it appears as if there really is scarcely a possibility that they ever could become so. By far the largest and most important deposits of lignite are those which have been somewhat exten- sively worked in the northern parts of the Duchy of Nassau ; and here these ter- tiary beds, although they exhibit every external appearance belonging to regular carboniferous deposits, are so loaded with earthy matter, which is intimately min- gled with their component structure, that they have not hitherto been made to give out a sufficient lasting heat to perform any of the important practical duties of fuel. Such is the case, also, with most of the tertiary and secondary lignites in other parts of the world. 328 COAL NOT UNIVERSALLY DISTRIBUTED. obtained by experience only, and as to a certain extent it partakes of the indeterminate nature of all negative propo- sitions, it may be considered as not yet sufficiently proved. But the evidence, if not complete, is at least exceedingly strong ; and the degree of probability that coal, as a valu- able mineral, is confined to the upper part of the Palse- ozoic series of deposits, is so great, as to be a safe guide in all the speculations of prudent men. It is not that other groups of strata have always been formed at a distance from land richly clothed with vegetation ; for, on the contrary, some (as, for instance, the Wealden formations) are entirely of freshwater origin, while the carboniferous system is almost exclusively marine; and others, as the beds of the lower oolites, are associated with sandstone and shales, loaded with vegetable remains. Other accumulations, also of ancient vegetable matter, are found in other beds, and indications appear in several of them of sandstones and shales, very similar to those associated with the coal ; but -the coal itself is always absent, or worthless, and a search for it in any bed of the Secondary or Tertiary period, seems sure to result in disappointment and fail- ure. The Geologist can only lay this fact before the practical miner as a rule of observation, but it is one of great importance, and it is an example in which a sufficient acquaintance with Geology may be the means of saving the expenditure of large sums of money, under circumstances where there was not from the first any rea- sonable prospect of success. Numberless instances might be quoted of vain attempts that have been made to obtain coal in other rocks than those of the Newer Palaeozoic period in Europe, and each experiment in succession has only served to strengthen the conviction that must exist in the mind of every ob- FAULTS IN COAL STRATA. 329 servant Geologist, that no exception is likely to occur to the general rule in this matter.* The other fact important to be duly considered by the practical miner, is that of the singularly frequent dis- turbances that have affected the beds of coal and the strata associated with them, and the remarkable com- plication of the faults that characterise every coal-field. It must not be supposed that the effect of these disturb- ances is either uniformly advantageous, or always disad- vantageous to the immediate interests of the miner ; but there cannot be the slightest doubt that we are indebt- ed to such disturbances for frequent repetitions of the same bed of coal at the surface, when without them it would be so far covered up by newer deposits as to be utterly unattainable. If occasionally the miner, in pro- secuting his labours, or the mine-owner in following what he considers a valuable seam of coal, is suddenly stop- ped by coming in contact with a fault, and finds the coal shifted several yards above or below, or even com- pletely lost, he must not forget that it is perhaps owing to these very shifts that the outcrop has taken place at all in his neighbourhood, and that the coal is work- * Nevertheless this rule, although so universally applicable on the continent of Europe, may not apply in other parts of the world. I make this reservation, be- cause the researches of Professor Rogers would seem to render it extremely pro- bable that some of the thick beds of coal in eastern Virginia, in the United States of America, may belong not to the Palaeozoic, but to the Secondary period, and re- present on a large scale the oolitic coal-field of Brora, the accumulations of vege- table matter at Scarborough, and the somewhat similar, and probably contempora- neous, beds at Cutch in the East Indies (see vol. i. p. 381). If this is the case, it will become an object of extreme interest to the Geologist to compare the unques- tionably Palaeozoic coal-fields of America with these which are supposed to be of Secondary origin, and in which a characteristic coal-plant (Stigmaria) does not at all appear. See the Memoir by Professor W. B. Rogers, in the Transactions of the Association of American Geologists and Naturalists. Philadelphia, 1843, p. 298, etseq. 330 FAULTS IN COAL STRATA. able throughout a very large proportion of the district in which he is interested. I have already (vol. i. p. 36) explained, by a simple illustration, the nature of the disturbances which would produce such systems of faults as are found in the car- boniferous strata, and in now offering to the consideration FAULTS IN COAL STEATA. AUCKLAND COAL DISTRICT, DURHAM. A. Main coal. B. Crow coal. c. Yard coal. of the reader a section of an actual coal district, in which the faults, within a given space, are represented to a scale, I need only refer to the hypothetical sketch given in the first chapter of the Introductory part of this work, to shew how strictly analogous the two cases are. But there is a most important advantage derived from the existence of these numerous faults in coal strata, namely, that they intersect a large field of coal in all directions, and by the clayey contents which fill up the crack accompanying the fault, become coffer-dams, which prevent the body of water accumulated in one part of the field from flowing into any opening which might be made in it from another. * This separation of the coal- * An instance of the advantage resulting from the presence of a great line of fault, occurred in the year 1825 at Gosforth, near Newcastle, where a shaft was dug on the wet side of the great ninety-fathom dyke, which there intersects the coal-field. The workings were immediately inundated with water, and it was found necessary to abandon them. Another shaft, however, was sunk on the FIRST DISCOVERY OF A COAL-SEAM. 331 field into small areas, is also important in case of fire, for in this way the combustion is prevented from spread- ing widely, and destroying, as it would otherwise do, the whole of the seam ignited.* The stratified condition of the coal, and the certainty of discovering the seam or bed in every part of a district known to contain carboniferous strata, would render the working for coal a mere mechanical labour, not requiring any special directions or any previous knowledge, were it not for the extreme abundance of faults, and the great influence they have upon the productiveness of a coal-field. But as a matter of fact, such previous knowledge, united with great experience, is exceedingly necessary, and re- quires to be founded on a familiar acquaintance with Geo- logical phenomena. One of the most simple, though not the least important applications of Geological knowledge in mining, may be exemplified by considering the case of a coal-seam cropping other side of the dyke only a few yards from the former, and in this they de- scended nearly two hundred fathoms without any impediment from the water. Buckland's Bridg. Treat, vol. i. p. 544, note. * This is not so hypothetical an accident as might, perhaps, be thought. Many instances are on record of such fires having occurred, sometimes sponta- neously from the decomposition of iron pyrites in contact with moisture, sometimes from lightning, and sometimes wilfully, in consequence of quarrels between the workmen and the coal-owners. When such fires do occur, they have been known to burn on slowly for many years, and within the last twenty years there has been more than one instance of extensive subterraneous fires, which have destroyed many acres of coal. 332 APPEARA.NCE OF COAL ON A HILL SIDE. out in a valley, since there are no less than three very distinct cases that may occur, in each of which the method to be adopted in working the coal must be contrived with reference to the Geological position of the bed, and not only to the fact of the coal cropping out. The first of these is when the dip of the beds is less than the angle at which the valley slopes, both being in the same direction. Such is the case in the annexed diagram (p. 331), and it is obvious that a shaft sunk anywhere on the rise of the hill, will reach the coal, the seam of which may be worked safely and with little difficulty, the newer beds being always the highest in position. In the case represented in the sub- joined diagram, however, where the dip of the bed is greater than the slope of the valley, and the direction is still the same, it is obvious by observing the section, that there could be no useful result gained by sinking on the rise, above the spot where the coal has once been seen, the older beds coming out on the rise of the hill. It will be observed, that in both this case and the former the outcrop of the coal occurs at about the same height on the rise of the hill, and that the alteration of the dip of the strata is the only point of difference apparent. The third case in which it is important to understand the Geological position of the coal strata is represented below, and occurs when the slope of the valley is in a dif- ferent and nearly contrary direction to the dip of the beds. In this case the newest and not the oldest beds will neces- sarily appear the highest, and the coal may safely be looked APPEARANCE OF COAL ON A HILL SIDE. 333 for at a certain calculated distance below the surface at any point of the section. A due consideration of these differences in the mode of occurrence of the coal strata will be sufficient to convince the reader of the importance of attending to Geological conditions in mining operations of this kind, and will also shew the great value of those accurate maps and sections, now preparing for publication as the result of the Ord- nance Geological survey. There can be no greater prac- tical benefit to be expected from the study of Geology than the publication and general use of those maps and sections ; and no one can fully appreciate them who does not look upon them with reference to this application, and to the certainty thence derived in mining operations of infinite importance to the commercial prosperity of England.* Having offered these preliminary observations, as to the circumstances of the occurrence of coal, let us next proceed to consider in what way, and under what con- ditions, the coal can be most conveniently extracted from * The nature of different kinds of valleys, an idea of which is attempted to be given in the above diagrams, is best understood by reference to models, where all the important points are at once seen. Such models have been prepared for sale by Mr. Sopwith, and they are also to be seen in the Museum of Economic Geo- logy. The outcrop of the beds in a valley is often marked by a V-shaped line, and the direction and position of this V depend on the dip of the beds, the slope of the valley, and the nature of the denudation. In a valley of denudation where the beds are horizontal, the V will, of course, be so too ; where the beds dip in the same direction as the slope of the valley, and their angle of inclination is less than that of the slope (as in the figure, p. 331), the point of the V will be upwards, while if the angle of dip is greater than that of the slope (fig. p. 332), the V will point downwards. 334 APPEARANCES OF A COAL DISTRICT. the bowels of the earth ; and these conditions, depending partly upon the nature of the coal itself, partly on the thickness of the beds, and partly on their depth below the surface at the place of working, and on the dip of the strata, it will be necessary to distinguish between the North of England coal-field, where the beds are of moderate thickness, exceedingly bituminous, and worked at great depths, and the carboniferous deposits in York- shire, Staffordshire, Warwickshire, and Wales, where they are often enormously thicker, contain far less gas, and can be conveniently obtained from depths much less con- siderable. The North of England, or Newcastle coal, being that chiefly made use of in England as a fuel, it will be convenient to bring it first under consideration. A recent French author, M. Piot,* has well remarked, that three persons travelling to Newcastle in different directions, would receive totally distinct impressions of the nature of the industrial occupations of the people. One traveller, for instance, coming by the railroad from Carlisle would cross an agricultural district, and might hardly notice the fact that any commercial value attach- ed to it, or that anything was capable of being exported, except, perhaps, the lime obtained by burning the moun- tain limestone of the district. Should his journey be made by night, he may have been struck by the appearance of flame vomited from the chimneys of the glass-houses near Newcastle, and those at Lemington, but a few coking ovens would present the only external indications of the real nature of the riches that abound in that part of England. Another person travelling from London by the steam- * Memoires sur Texploitation des mines de houille aux environs de Newcastle- sur-Tyne. Annales des Mines, 1842. APPEARANCES OP A COAL DISTRICT. 335 boat, would probably admire and wonder at the vast multitude of vessels engaged in the coasting-trade of Britain, and his attention, perhaps, would be mainly di- rected to the vessels engaged in that branch of trade he was about to investigate. But it would not be till his arrival at the mouth of the Tyne, that he could form a sufficient idea of the true commercial importance of the northern counties ; nor, until he had observed the numerous and well-built vessels in that river, and had seen the coal raised from a vast depth below the sea- level, and deposited on board these vessels, and his enthu- siasm had been kindled by the animated appearance of the port of Newcastle, would he fully feel his own littleness, and his inability even to comprehend, in all its detail, so vast a development of national industry. But the third traveller coming from Birmingham, and who has traversed the series of coal formations which extend from the middle of England northwards, and which he would also cross in the county of Durham, would, beyond all doubt, have the best idea of the riches of the country. Throughout his route, he could not but have noticed that everything is sacrificed to the coal, and the great works going on underground, would be an- nounced to him by the immense apparatus erected on the surface for the extraction of the mineral riches, and for the drainage and ventilation of the mines. He would have seen the innumerable tram-roads, and their long succession of waggons laden with coal. He would have asked the meaning of the numerous extensive towns, built of uniform habitations, visible at intervals along the road, and could hardly, perhaps, express his astonishment at learning that they were all the dwellings of the tens of thousands of pitmen. 336 NEWCASTLE COAL-FIELD. But the impressions made on each of these three tra- vellers must be united if one would acquire even a feeble and imperfect notion of the chief points of interest which the coal-mining district of the north of England offer for consideration. The Newcastle coal-field is bounded on the north by the river Coquet, and on the south it extends nearly to the Tees. Its extreme length is thus about forty-eight miles, and its extreme breadth measures twenty-four miles, but its area cannot be calculated at more than 800 square miles. It is intersected by two navigable rivers, the Tyne and the Wear, on the former of which is situated the town of New- castle, and on the latter the city of Durham. The whole field is divided unequally into two parts by a great fault crossing the district a little north of the Tyne, and throw- ing down the strata on the northern side (or raising them on the south) to a perpendicular distance of ninety fathoms. This principal fault is usually called the ' main dyke, 1 and there are besides many extensive faults and dykes through- out the district. There are as many as forty distinct beds of coal in the Newcastle coal-fields, but eighteen of them only are suffi- ciently important to be considered workable. The most valuable is called the High Main, and is about two yards thick. The Bensliam seam is the next in value, and is remarkable for its excellent quality, and for the enormous quantity of gas evolved from it in the mine. The Hutton seam is also much worked, and is of good quality ; and the rest are variable. No ironstone, and only a small quantity of iron ore of any kind is found associated with the coal in the Newcastle coal-fields. When by the various methods already described, or by BORING FOR COAL. 337 previous knowledge of the district, the presence of coal is ascertained, the first operation to be undertaken before opening a coal-mine is usually that of loring to discover the most advantageous spot for sinking a shaft, and ex- tracting the coal. This is often necessary, owing to the extreme complexity of the various systems of faults in the district, and the impossibility of otherwise determining with certainty the prospects of sinking. The operation of loring is generally effected with a kind of chisel, which being attached to an iron rod by means of a screw, and worked by a little temporary machinery erected on the surface, makes its way by alternate chopping and scooping, the accumulation of rubbish being taken out from time to time by an auger, as the chisel becomes clogged. Successive lengths of rod are screwed on as the work advances, and the nature of the strata gone through is determined with considerable facility and cer- tainty by examining the fragments brought up by the auger. The expense of this operation varies, of course, greatly, according to circumstances ; but through strata of moderate hardness the average cost per fathom may be stated at somewhere about 12s. within ten fathoms of the surface, and 6s. more per fathom after every five fathoms increase.* When in this way, or from previous knowledge of the district, it is decided where a shaft shall be sunk, this important work has next to be commenced. The shafts in the north of England are usually cylin- drical, or elliptical, and the smallest diameter is about ten * Thus, at 60 fathoms the cost would be (since the extra depth is 50 fathoms) 12s. + 6s. X 10 = 12 + 60 = 72s., or 3. 12s. per fathom. This price must be understood as merely an approximation, and is often much higher ; but what- ever the nominal cost may be, rocks that are unexpected, and of great hardness, (such as porphyritic dykes,) are paid for extra. VOL. II. Z 338 SINKING A SHAFT. feet. The smaller shafts are generally divided throughout into two compartments by an air-tight wall of separation (a brattice), but the larger ones, which have a diameter of as much as fifteen feet, are divided into three parts, and the section or horizontal plan of one of these shafts is repre- sented in the annexed cut. One of the compartments is made use of for drawing the coal to the surface, another for the drainage of the mine, and a third for ventilation, convey- ing to the surface the air that has SECTION OF THE SHAFT OF passed through the workings. A COAL MINE. Under the most favourable cir- cumstances, the sinking a shaft is a work of consider- able time and expense, for it is necessary to line almost the whole interior with bricks to prevent the loose and incoherent strata from falling, or being washed in ; but it rarely happens that any depth of shaft can be sunk without meeting with springs of water, which sometimes empty themselves into the workings to an extent which it would at first appear hopeless to contend against. In such cases there is no safety to be obtained without lining, with a strong framework, that part of the shaft which passes through the loose permeable sands. This lining, of the shaft is called tubbing, and many pits around Newcastle and elsewhere, (where extreme dura- bility is required, and no expense is spared to obtain this object,) were formerly lined throughout with three-inch boards nailed to a circular wooden framework, called a crib, which was firmly attached to the sides of the pit at convenient distances. But this method, although it has been known to keep out a pressure of water equal to 100 Ibs. on the square inch, is not considered so safe as the DEPTH OF SHAFTS. 339 metal tubbing now adopted in all difficult works. In some recent shafts as much as forty fathoms of a pit have been in this way completely lined with a strong cast-iron casing. The depth of a shaft must, of course, vary indefinite- ly ; but in the Newcastle coal-field it is rarely less than twenty-five fathoms, or 150 feet. The most common depth is, however, much greater than this, pits being sometimes sunk to nearly 300 fathoms (1 800 feet,) and an expense of upwards of 50,000. being often incurred before the seam of coal has been reached which it is intended to work.* It is usual in the deeper workings to have but few, or only one shaft, owing to the great expense of sinking ; and it is the opinion of some of the most intelligent coal- viewers, that in this way, independent of all economical considera- tions, the deep workings are more conveniently and per- * The most remarkable and enterprising work of this kind on record is a sink- ing at Wearmouth colliery, near Sunderland, commenced in 1826, through the capping of magnesian limestone. The lower beds of the magnesian limestone and the lower new red sandstone here overlap the coal-measures, and at the place of sinking their thickness was known to be upwards of three hundred feet. At a depth of three hundred and thirty feet accordingly the coal strata were reached, but, at the same time, a spring was tapped, which poured water into the workings at the rate of three thousand gallons per minute. This fearful influx was kept under by a steam-engine of two hundred-horse power, and the work was made secure by strong metal tubbing, and carried on successfully, though not without extreme difficulty. On entering the coal-measures, however, a new and unexpected check was ex- perienced. No calculation had been made for the extra thickness of the upper- most coal strata in those parts where the upper beds had been protected from denudation. This was found to require a much deeper sinking than had been expected ; and the difficulties were increased when, at the depth of one thousand feet, a fresh feeder , or spring of water, was tapped. Additional expense and great loss of time was thus caused ; but the proprietors persevered, and continued the sinking to the depth of 1578 feet, where they were rewarded by reaching a seam of considerable thickness and value. This was supposed to represent iheBensham seam, and they therefore resolved to continue the work in order, if possible, to reach the ' HuttonJ the most valuable of all. The expense of this pit, including the necessary preliminary operations, could not have been less than 100,000, and at least ten years elapsed before any result was obtained. z 2 340 DRIVING LEVELS. fectly drained and ventilated, and that the general work of the mine goes on better.* It is rarely necessary in the coal-fields in the middle or west of England, or in Wales, to sink so deep for the coal, or undertake such costly works in order to obtain it ; but the method of sinking is, of course, the same. In many places, however, it is found more convenient to sink a number of pits of smaller size than one large one, and in this way to avoid the extensive underground operations required in the north to effect the ventilation of such mines as have only a single shaft. The thickness of the coal in Staffordshire also renders it expedient to resort to methods of working on a principle somewhat different to that followed in the Newcastle coal-field, and these methods will require to be spoken of separately. The shaft being sunk, it is usual to drive two galleries or levels, the one along a horizontal line on the strike of the coal-seam, and the other at right-angles to this on the rise of the bed. The former is called the drift, or water- course, and has important reference to the drainage of the mine, and the latter is the winning headway or main thoroughfare, through which the coal is conveyed to the shaft when extracted from the galleries afterwards cut. These two principal and preliminary cuttings are usually of considerable dimensions, (from nine to twelve feet wide, and six feet high,) admitting of the passage of loaded waggons and horses, and they are almost always provided with a tram or pair of rails. In the shallower * It must be confessed that this opinion seems hardly reasonable when the great extent of the underground works to be thus ventilated is taken into con- sideration. In some mines upwards of seventy miles of passages, more than a hundred fathoms below the surface of the earth, are only provided with one pit, not above twelve or fourteen feet in diameter, for ventilation, drawing coals, pumping water, and every operation necessary between the surface and the works. NOXIOUS GAS IN COAL-MINES. 341 mines, and where a second shaft is sunk, the new shaft opens at the extremity of the winning headway, and ven- tilation is at once established. VENTILATION OF COAL-MINES. TWO SHAFTS. The safe and economical working of coal-mines, more especially in the north of England, where the coal gives out a vast quantity of noxious gas, depends so intimately on the steps taken from the first to keep the works in a proper state of ventilation, that I shall make no apology for entering at considerable length on that subject. Mines are well known to be subject to certain special accidents, and of these, the occasional presence of air unfit for respira- tion, the falling in of the roof, the incursion of an unusual quantity of water, and many others, are common to all, and are perhaps scarcely greater, or more serious, than those accidents which are constantly recurring in other employments. But in addition to these, and far greater than any of them, there is a cause of accident peculiar to coal-mines, and most peculiar to those of greatest economical value, those, namely, which supply the metropolis with its millions of tons of fuel, and which must and will be worked with every kind of energy, and in spite of every risk, so long as they continue to be a source of profit. The Newcastle coal is well known to abound with carburetted hydrogen gas, which it always gives off readily when exposed to heat, but which is also evolved sometimes slowly and insensibly, but sometimes with extreme rapidity, when undergoing the 342 NOXIOUS GAS IN COAL MINES. great pressure of the superincumbent strata in the mine. This gas, it is also known, is itself immediately fatal when breathed instead of air, but when it is mixed with a certain variable proportion of atmospheric air, it becomes highly explosible on the slightest contact with flame. It is much lighter than common air, mixes very readily with it, and, wherever it is poured out into the workings of a mine, rushes with the moving column of air in the nearest direction to the ascending shaft ; but, if it meets in its way with any ignited body, there is an immediate and fear- ful explosion, usually fatal not only to all in the immediate neighbourhood of the accident, but, by means of what is called the after-damp, (the gas formed during the explosion, and remaining after it,) involving also in destruction all those in all parts of the workings who are obliged to pass through this noxious gas on their way to the shaft which communi- cates with the upper air. This being the case, it becomes an imperative duty of the very first importance, that all possible care and attention should be paid in arranging the underground works of a coal-mine, with reference to these points ; namely, first, that the system of galleries should be so con- trived for the extraction of the coal that no part shall be left without a current of air passing along it. Secondly, that every communication with old workings in which the fire-damp (as the carburetted hydrogen gas in mines is called) may have collected, should be permanently and effectually built off. Thirdly, that no working should go on in parts of the mine distant from the shaft without every pos- sible precaution being taken to ensure the rapid ventilation of the main passages, and that such distant and detached workings should be as much as possible avoided. Fourthly, ROOF AND FLOOR OF THE MINE. 343 that all possible contact of flame, in a dangerous working, should be prevented, and that this should be attended to not only in the dangerous part of the mine, but in the main passages. And, fifthly, that a steady and effectual venti- lation, in every part of the mine not actually cut off by strong partition walls or brattices, should be constantly kept up. The method of working must, however, be decided on not only with reference to these considerations of safety to the miner from the chance of explosion, but also after all possible information has been obtained, and calculation made as to the sustaining powr of the roof and floor, the strata above and below which the coal is deposited. For it must always be remembered that although so long as the coal remains in its place there is no extraordinary pressure, every part being equally and proportionably sustained, yet so soon as the excavation has commenced, and empty spaces are left, the roof, if sufficiently coherent, causes the whole superincumbent weight to act on those portions of coal that may be left in the mine, and which in that case act as pillars. If then the roof consist of hard sandstone and the floor of soft clay, the pressure downwards will tend to displace and force up the floor, and crush the coal. If, on the other hand, the roof be soft, it will sink in, and if both roof and floor are moderately hard and tough, they will, after a time, meet each other mid- way. I have endeavoured to represent these different appear- ances in the annexed diagram, where the roof and floor in the different galleries of which a section is given are in various conditions, produced by the pressure of the super- incumbent beds in different ways. The third space to the 344 METHODS OF WORKING COAL. right (c) represents the gallery with the roof and floor un- disturbed, both being hard, and the effects of a soft floor are represented in the first and second compartments (#, #). a b c d e f DIFFERENT KINDS OF CREEP IN COAL-MINES. The effect resulting when both floor and ceiling are soft, are shewn in (o?), while in (V), (/) the whole of the roof is re- presented as having fallen in, the coal is crushed, and the surface of the country exhibits evidence of this underground change.* Having acquired a knowledge of the nature of the coal itself, and of its floor and roof, it is always a most im- portant problem to be solved by the coal-viewer, how far he can safely proceed in taking away the coal ; and he must also consider whether there is much prospect of his being able ultimately to take a second portion by very carefully and moderately working the seam at first, and in what way the maximum of produce can be obtained, with the minimum of danger and loss. In the Newcastle coal-field, where the coal is full of gas, where the best seams are worked at very great depths below the surface, and where the strata associated with the coal are often soft and incoherent, it is usual to extract the coal by cutting a number of galleries parallel with each other, * The rising of the floor is called in mining language, the creep., and marks of its existence are often seen on the surface. The contrary accident, the sinking in of the roof, is called a crush, and in avoiding these two accidents consists the diffi- culty of working the pillars. PANNEL-WORKING. 345 and intersected by others at right-angles thus isolating between four such galleries a pillar of coal whose dimen- sions vary according to circumstances. In the description already given of the first operations of mining after the shaft is sunk, it has been mentioned that two levels, the drift and winning headway, are first com- pleted, and after this other galleries are sometimes driven parallel to the winning headway. These galleries are of different dimensions, the larger ones, which are nine or ten feet wide, are called boards, and they are intersected by other galleries at right angles to them whose dimensions are not quite so large, and which are called narrows. The pillars of coal left between these galleries are from eight to nine yards thick, and until the close of the last century this method was the only one employed in deep work- ings, at least sixty per cent, of the coal being left in the mine. About fifty years ago, however, an attempt was made, for the first time, to remove a part of the pillars, and a method was devised by which 54 per cent, of the coal was obtained, and afterwards, this method succeeding, al- ternate rows of pillars were abstracted, and sometimes even half the intermediate ones. Lastly, Mr. Buddie invented the method called pannel-work, by which nearly the whole of the coal may be obtained with safety. This method consists in dividing the mine into districts or pannels, separated from one another by walls of coal forty or fifty yards thick, and extracting the coal from each of such pannels in succession, usually beginning with the one most distant from the shaft, and completely shutting off all communication with the rest of the mine as soon as any pannel is worked out. In the diagram, page 355, and also in page 358, is seen an ideal plan of pannel-work. 346 METHODS OF WORKING COAL. Large pillars are at first left between the boards, (which are four yards wide,) and the transverse galleries, or rooms, (two yards wide,) and the dimensions of the pillars are about twelve yards by twenty-four. As soon as the galleries are finished, and the work of abstracting the pillars commences, the roof is at first supported by stout props of Scotch fir, and when these are also removed, the roof falls in ; but the whole of the workings are under the most perfect control so far as ventilation is concerned, and any part can at a moment's notice be shut off from the current of air running through the whole mine, should such an event be required. The great advantage then of Mr. Buddie's plan is, that while a large proportion of the whole bed of coal may be by its means extracted, the ventilation may be always per- fectly well preserved, and the risk of danger from accumula- tions of gas in old workings almost entirely avoided, be- cause these old workings can be completely cut off from the mine as soon as they become in a dangerous state. Such being the method of working in mines where there is danger to be anticipated from the fire-damp, let us next shortly consider the nature of the different and simpler contrivances followed in those districts where the coal is MQi fiery, and where the associated beds are sufficiently hard and coherent to support themselves without fear of accident. In the Yorkshire collieries, as may be understood by ex- amining the annexed diagram, there is something of the regularity observable in the mines of the Newcastle coal- field, but a greater proportion of the coal is worked out at first, and only a wall of coal is left. In the diagram the dip of the coal is supposed to be to the west, and two pits or shafts are sunk, communicating by a gallery called YORKSHIRE, OR LONG METHOD. 347 West. METHOD OF WORKING COAL IN YORKSHIRE. THE LONG METHOD. a. Engine pit, ft. Working pit. C. Drift d. Horse-gate. X. Water-gate. 6 Main Beard-gate. f. g. Various headways. H, The face of coal worked. k. Coal extracted, and roof sup- ported by pillars. I. Coal extracted, and roof fallen the drift. From the lower, or engine pit, a gallery is cut on the strike, and likewise another from the working pit, and these are called respectively the water-gate* and the horse-gate. From the bottom of the working pit a main gallery is also driven on the rise of the coal, and this, which corresponds to the winning headway of the north of England, is here called the " main board-gate. " Other galleries, parallel to this, are also cut, and the coal is then worked from the intermediate pillars, leaving only a narrow wall, and allowing the roof to fall in after those temporary props are removed which supported it while the works were advancing. In Staffordshire again, where the seam of coal is of ex- treme thickness, and consists in fact of several beds united, * The word gate in Yorkshire retains its ancient meaning, derived from the Saxon verb gangan, to go, and is commonly used to signify a road, or way. 348 METHODS OF WORKING COAL. the method is somewhat different, as there only a few ir- regular pillars are left ; but there is still a wall of coal, although little regard is paid to those conditions which are justly considered as of the most vital importance in the mines of the Newcastle coal-field. WORKING THICK BEDS OF COAL IN STAFFORDSHIRE. a, 6. The pita. The system of ventilation must of course be nearly the same in its general plan, whatever be the nature of the mine to which it is adapted, and therefore, in describing the most complicated and perfect arrangements of this kind, as carried on in the fiery seams of Newcastle and its neighbourhood, it will hardly be necessary to mention the smaller degree of the same care and attention paid in the less dangerous workings of other districts.* * Perhaps it is advisable, before proceeding to give a detailed account of the ventilation of coal-mines, that the reader should be made acquainted with some technical terms that will be used in the description. A brattice is a wall of separation. Brattices are of two kinds ; either perma- nent, and separating a shaft into two or more divisions, in which case it is a strong parapet wall, sometimes as much as three feet thick ; or temporary, and consisting VENTILATION OF COAL-MINES. 349 There are various modes of inducing the current of air by which the ventilation of mines is to be effected, but the most common is by rarefaction, a powerful fur- nace being placed at the bottom of the upcast pit. In some cases, however, it is not safe to resort to such an expedient, in consequence of the quantity of gas poured out in the workings ; and when, owing to this or any other reason, the furnace cannot be used, a hot cylinder has been substituted, or a current of air produced by throwing a column of water into the downcast shaft, or by pumping out the air by means of an air-pump from the up-cast; but all these are partial and imperfect contrivances, and have many great disadvantages. The simple furnace has been proved by experience to only of a frame-work of three-inch deal, readily moved to any part of the under- ground workings. Stoppings are also walls made of brick, stone, or timber, and their object is to prevent the current of air from passing in a given direction. Trap-doors are moveable substitutes for stoppings in the great thoroughfares of the workings. They are of several kinds ; as main-doors, which are in sets of two or three, and always fixed in the strongest manner, and provided with boys to open them upon a signal, and take care that two of the same set are never open at the same time. Man-doors are of small size and communicate with the dangerous parts of a mine. Sheth-doors are those which purposely allow a considerable de- gree of leakage ; and sham-doors are a kind of trellis- work, only intended to check the current of air. The air-course is a general name for the air traversing workings where venti- lation is going on. The fresh air descending into the mine is called the " in-takef and that which ascends, after having passed through the workings, is the " return" CROSSING A CURRENT OF AIR IN A COAI.MINE. A crossing is where a current of air crosses another current by means of an arch, as is represented in the annexed diagram. That part of a mine which is not included in the ventilation is called the waste. 350 VENTILATION OF COAL-MINES. be the most convenient method of producing a current of air,* but before mentioning the additional contrivances of this kind it may be well to say a few words concerning the condition of the underground works, with reference to the ascending and descending current, and the nature of the necessity of such artificial means of ventilating deep coal-mines. At all great depths below the surface of the earth, the temperature is constant, or at least has no changes corresponding to those which take place on the surface, and it has also been found by experience, that below a certain depth, at which the average temperature of the surface for the whole year is reached, the temperature increases with great regularity .*f- Thus the air in a deep mine is usually warmer, and therefore lighter, than the external air, and would rise up through a shaft, and be replaced by the colder and heavier air from above. If there were two shafts, an air current would soon be esta- blished in the workings, and one of the shafts would become a downcast, and the other an upcast pit, in the technical sense of these words. But it will easily be seen, that a current of this kind would be very variable, and in extensive workings, where its course is checked by having to pass through a number of galleries, must be totally insufficient for the purpose of ventilation. Where there is a large number of shafts, this evil may, it is true, be avoided in some measure ; but in coal-mines where there are very few, a natural * A method of producing such a current in coal-mines has been projected by Mr. Goldsworthy Gurney, and is very highly recommended in the report of the South Shields Committee for the investigation of accidents in mines. It consists of jets of high-pressure steam applied at the bottom of the upcast shaft, and is meant to be used with rather than supersede the furnace, producing the same effect of rarefying the air in the upcast shaft. f Vide note, p. 294. FURNACE. 351 ventilation would not be sufficient even if there were no danger to be anticipated from the escape of foul air. The effect of a large fire at the bottom either of a shaft, or of a division of the shaft, is to add considerably to the rare- faction of the air as it passes out of the mine, and in this way to produce a rapid ascending column of hot air, whose place is immediately supplied by a rush of cold air from the surface, and this cold air, passing down the other pit, or another compartment of the shaft, and through the workings, is gradually warmed, until at last it reaches the furnace, and itself becomes the ascending column.* Such is the advantage of the furnace in assisting to provide a supply of fresh air; but while admitting this advantage, and acknowledging that it is quite as much felt in a single shaft divided into compartments as in the case of two or more shafts having the same total area, it is also right to mention the necessity there is in the former case of having the two compartments quite distinct for a sufficient distance from the bottom of the mine, so as to avoid all risk of the partition wall between them being destroyed by any explosion that may take place. ( Mr. * The * standard air-courses,' or, in other words, the supplies of fresh air passing into a mine, vary considerably. In the Wallsend colliery they were stated by Mr. Buddie to vary from two thousand to three thousand cubic feet per minute, but occasionally to reach three thousand eight hundred cubic feet. In some of the large collieries the air has to traverse many miles of gallery be- fore being discharged, and often does not return to the surface in less than twelve hours from the time of its descent. The rate at which it moves varies, of course, according to the circumstances of the mine ; but from two to two and a half feet per second is perhaps an ordinary rate, when there is no especial danger. It is sometimes, however, even less. f Very serious and terrible accidents have happened, owing to neglect in this important matter. After an explosion, it is not at all unlikely that many per- sons working in a distant part of the mine may be quite uninjured ; but if, owing to the want of separate pits or proper precaution, the brattice between the down- cast and upcast shaft is blown away, these unfortunate people must necessarily fall victims ; for it will be quite impossible for them to make their way through the 352 VENTILATION OF COAL-MINES. SECTION OF THE BOTTOM OF A SHAFT. Shewing the subdivision of the lower part into two shafts. Buddie, aware of the great danger incurred with regard to this point, found it ex- pedient to let there be two shafts within a certain dis- tance of the workings, al- though only one might be carried to the surface. The air which is to feed these furnaces being that which has passed through, and which carries with it all the impurities of the mine, must often be in an unfit state to support flame, and is occasionally even explosible. In this case the portion coming from the inflammable part of the mine is sometimes separated, and passed by means of an inclined air-course into the shaft, at a safe distance ILLUSTRATION OF A DUMB FURNACE. a the furnace ; b, the current of foul air drawn up into the shaft (c), without being passed over the furnace. above the fire, this contrivance being called a cold or dumb furnace. If, however, none of the air that has traversed the mine is fit to supply the fire, a portion of the descending current is sometimes employed for this after-damp, (which will, in fact, be carried through the workings by the in-tdke,) and there will be no possibility of immediately restoring the ventilation to any part of the underground works. PARTIAL CURRENT OF FRESH AIR. 353 purpose immediately. A contrivance, , by which the air may be thus diverted, is represented in the annexed diagram. VENTILATION OF COAL-MINES. PARTIAL CURRENT OF AIR TO FEED THE FURNACE. Iii this diagram, which represents a plan of the ar- rangements adopted at the bottom of a pit in the Percy Main Colliery, the shaft is single, but divided by a stout brattice ; that part marked (a) is the upcast portion, and (b) the downcast. The air, following the direction of the arrow-head, usually passes by a door into a cham- ber provided with a furnace at (c), and so into the up- cast shaft. Should, however, danger exist, and the cur- rent of air become too foul to be safely passed over the furnace, it is forced to pass into the upper part of the shaft, by closing the door ; while, on the other hand, a portion of the descending current can be allowed to pass over the furnace immediately by removing the brattices marked in the diagram, and in this way a suf- ficient draught is obtained to carry the foul air to the surface, without bringing it into contact with the fire. In the preparatory works of a mine, the ventilation is effected by means very similar to those afterwards adopted in the more extended operations. As soon as a pit is sunk, it is either put into communication with VOL. II. 2 A 354 VENTILATION OF COAL-MINES. another pit, if there is one, or if not, the principal gallery, the winning headway, is immediately proceeded with. It is usual, in such case, to drive two parallel headways, which communicate with one another by cross-cuts, called stentingS) through which the air being conducted, a cir- culation is immediately esta- blished, and as the work advances, and new stentings are required, the former ones COMMENCEMENT OP WORKINGS IN A COAL-MINE IN TWO PARALLEL HEAD- WATS. are closed by a which is usually a wall of brick. When only one gal- lery is driven, a moveable brattice is continued from the bottom of the shaft, forcing the air round by the extremity of the drifts and galleries. a. Downcast pit. b. Upcast. C. Stopping. d Brattice. PLAN OF FIRST WORKINGS IN A COAL-MINE. SINGLE HEADWAY. Without dwelling on the contrivances formerly in use, let us now turn our attention to an example, in which the PANNEL- WORKING. 355 method of pannel-work is followed in the extraction of the coal, and the most complete system of compound ventilation is brought to bear upon an extensive mine. The reader will perhaps require to be informed, that when a current of air is once in motion in the work- ings it will readily divide itself, and pass along every gallery open to it, provided, of course, that it is able constantly to advance, and is not checked by any wall or stopping. This division and sub-division of the air in the mine, is a matter of great consequence, and was first taken advantage of by Mr. Buddie. I now proceed to describe the working, with reference to the diagram annexed. In the figure, A represents the shaft for the descending, and B for the ascending column of air ; but they may, also, represent two of the three compartments of a large shaft, the third compartment being used for the general purposes of the mine, but also serving as a descending shaft. The air arriving at A, first enters the mothergate. or principal headway, A, and when it reaches d, divides into three parts, one of which continues along A, and the other two enter the compartments A' and B', passing into the latter by means of a crossing, (not marked in the cut,) such as that figured in page 349. These two cur- rents traverse the boards by the method of coursing the air, (forcing it to pass through all the galleries,) and the current which traverses B' unites with that which has passed through A' (traversing the crossing from / to g) and proceeds directly to supply air to the furnace at the bottom of B. The current which continued along the mothergate will be seen to divide again at h into two parts, one of which ventilates the compartment c, where the pillars are being 2 A 2 356 VENTILATION OF COAL-MINES. IDEAL SECTION OF PA NN EL- WORK TO ILLUSTRATE THE METHOD OF COMPOUND VENTILATION. worked out, while the other proceeds along the headway to , and again divides, one part passing into D, and the other to the end of the headway. The air proceeding from c, after it has traversed those workings, is sent on in one of the galleries parallel to the mothergate, and passing the compartment E, which is entirely cleared of coal, unites itself at c with a small proportion of fresh air, and then passes before the old works at F, and uniting with the current which emerges from D, goes through the dumb furnace to the ascending shaft B. FIRST COMMENCEMENT OF PANNEL-WORK. 357 The air is forced to take this long and tortuous course by means of a proper arrangement of stoppings and trap- doors. The management of these is entrusted to a num- ber of persons, and they are all under the superinten- dence of a superior class of miners called wastemen. It is the overman's duty to overlook these latter, and to watch constantly for the slightest changes of appearance that may take place in or near the old workings. The underviewer, and his superior the viewer, or director of the mine, are responsible for all necessary arrangements, and for the planning of all changes and new works that may be undertaken. The almost complete command that is obtained by the method of pannel- working, will be now readily under- stood. The old works E and F, however dangerous, may be cut off entirely from all communication with the rest of the mine, by stoppings in the mothergate ; and any one pannel is quite independent of the rest, and may be made to communicate immediately with the purest and freshest current of air in the mine. That portion of the air which passes the most dangerous places, is not passed through the furnace ; and an accident may happen in one part, without risking the lives of those employed at a distance. Perhaps, however, it will give a more distinct notion of the actual perfection of which this system admits, to exhibit a little more in detail, one of the early specimens of pannel-work in a dangerous mine. The annexed dia- gram is copied from the first illustration by which Mr. Buddie explained his system of compound ventilation. The works are here represented as being very little deve- loped ; the two long parallel galleries are the headways ; those joining them at intervals the ttenting, and the shorter 358 VENTILATION OF COAL-MINES. ones, extending irregularly, and opposite one another in sets, are the boards. The air, divided at its entrance into the mine into two different currents (indicated by PANNEL-WOKKING. the arrows), returns ultimately to the third compartment of the shaft; but that only which is supposed to be pure passes over the working-furnace, and the rest following the dumb-furnace, comes into the shaft at a higher level. This will be readily understood by examining the diagram. The reader will now be able to comprehend the nature of the principle of the most approved system of working coal, but its advantages can only be duly appreciated, when the methods it has superseded are also known. It is due to the memory of the late Mr. Buddie to state, that the most important of these improvements were in- troduced by him, and that he has thus contributed to GETTING THE COAL. 359 benefit mankind to an extent which it is not easy, per- haps, at present, fully to comprehend. Having said so much generally on the methods of ven- tilating coal-mines, I shall conclude this account with a few words descriptive of the process actually followed by the miner in extracting the coal from its bed. The working tools of the collier are few and simple, and consist chiefly of different forms of the pick, the most useful of which is a kind of mattock, with both ends of the head pointed. Besides this, chisels of various kinds, crowbars, hammers, and wedges, make up almost the whole list. The coal is in almost all cases readily detached by blasting, and is then easily broken up into cubical masses by taking advantage of the natural joints or vertical cracks which traverse it in various directions, and which occur generally in sets parallel, and at right-angles to one an- other. Besides these the coal is also characterised by what are called partings, parallel to the stratification of the beds. The usual method of getting the coal is by blasting, and this is effected by piercing the lower part of the seam, with a hole about an inch .in diameter, and a yard deep, into which the charge is inserted in cartridges, and the hole is afterwards plugged with coal-dust. When the blast has been fired, the coal is broken up by the work- men, who are usually paid according to the number of tubs, or corves, they are able to fill. These corves are conveyed on tram-roads through the mine, and ultimately lifted by machinery to the surface. The men employed in actually getting the coal, are called hewers; the loaded waggons, or corves, are conveyed along the tram by lads called putters, as far as the principal galleries, or headways, and are there received into waggons called rolleys, several or 360 DIFFERENT METHODS OF WINNING COAL. which being attached together, they are drawn by a horse to the bottom of the shaft. I shall not speak now of those contrivances by which the miner is enabled to pursue his work in some degree of safety in those fiery mines where the exposure of flame would be a constant source of imminent danger. The accidents of coal-mines, and the means of preventing them will form the subject of another chapter, in which the safety-lamp will be described, and I therefore postpone for the present any further allusion to it."* I have already given in the commencement of this chapter, some general statistical facts with regard to the extraction of coal in England, and have spoken at sufficient length of the methods used in extracting^it, both in the Newcastle and Yorkshire coal-fields. In these the coal is always of moderate thickness, rarely exceeding a few feet, but in the Dudley coal-field, where, as has been already mentioned, the thickness amounts to thirty or forty feet, both the methods of working and the nature of the dangers and difficulties incurred are very different. The coal is there worked in chambers, called sides of work ; the ventilation is simple, the danger from fire-damp comparatively trifling, and the principal difficulty arises from the great extent of the valuable part of the seam, and the risk of the upper part falling when the lower is cut away. In many parts of South Wales, and in the Forest of Dean, the mines are worked from the adit level, nor have they been undertaken for a sufficient length of time to require the expensive and * I would not be understood to mean that any method of lighting that can be adopted ought for a moment to supersede the most careful and incessant attention to ventilation. Ventilation is beyond all measure the most important, and should almost be looked on as the only safeguard against accident ; but I postpone the consideration of safety-lamps, as being totally independent of the mechanical details of mining. HIGHLY INCLINED SEAMS. 361 difficult contrivances absolutely necessary in the deeper and longer worked mines of the north. The great Scotch coal-district, occupying the basin of the Clyde, is worked to a considerable extent by means of numerous small but somewhat deep pits. Most of the large towns of Scotland are supplied from these works. The coal, as it occurs in England, is generally so nearly horizontal that all the mining arrangements have reference to this position ; but it sometimes happens, both in the east of Scotland, and in South Wales, that the seams of coal are inclined at a very high angle. In both these districts the depth of the shafts is moderate, rarely exceeding 100 fathoms ; and the mine is often open to the day, by means of an adit leve] entering the lowest part of the workings from a hill side. In Scotland the seams are narrow, the galleries low and wet, and the arrangements on the whole on a very primitive scale ; and until lately, females were often employed in conveying the coal along these narrow levels to the main roads, crawling backwards and forwards with their small carts, in galleries which, in many cases, do not exceed from twenty-two to twenty-eight inches in height. This painful and unreasonable labour is, however, quite unnecessary, for in Pembrokeshire, and South Wales, where the strata dip at an angle of from 45 to 60, the practice of coal bearing is entirely unknown. In this district the methods of working are of two kinds, the most common of which is illustrated by the annexed plan and section. The mine is worked by an adit or level coming out on a hill side, and above the adit. Windlasses are fixed at convenient distances on the incline of the vein, and the coal after being brought from the stalls, or places of working, in carts, is dropped by the chain of the windlass 362 WORKING PITCHING VEINS. down the incline to the level road ; the empty carts are worked up to the stage of the workings by the opposite chain of the windlass to which they are fixed. PLAN AND SECTION OF WOBKINGS IN PITCHING VEINS IN SOUTH WALES. If, on the other hand, the coal is worked to the dip, and below the adit level, the coal is, in a similar manner, worked up to a convenient stage by the windlass, and is then taken in the usual way by a shaft to the surface.* Besides these methods of working a steep face of coal in England, where, unless the circumstances are in other re- spects favourable, the extra expense would render the at- tainment of the coal unprofitable, it has been found necessary on the Continent to have recourse to others, more nearly resembling mining operations in mineral veins. As an ex- ample of such methods I have introduced a diagram repre- senting the working of a seam of inconsiderable thickness, * Children's Employment Commission. Appendix to First Report, Part II., p. 475. INCLINED SEAM OF COAL IN BELGIUM. 363 in the department of the Saone-et-Loire, in France. This working is sufficiently remarkable for some of its details. WORKING A HIGHLY INCLINED SEAM OF COAX : EAST OF FRANCE. In this case the preliminary operations have included eight stages of galleries or levels to meet the seam, all the levels communicating with the same shaft by means of other galleries at right angles (represented in the diagram,) cut in the rock which forms the roof and floor of the vein. The portions of the seam contained between two of the stages have afterwards been excavated by galleries cut on the dip, each portion into which the seam is thus cut being carried away by means of the gallery below it ; the successive por- tions being excavated from above downwards. In North America, on the other hand, in the State of Pensylvania and elsewhere, the coal is often fairly exposed to the light of day, and lies in stupendous masses, which are quarried in the open air. The coal is here anthracitic, or non-bituminous, and its thickness is variable, being sometimes fifteen or twenty feet, and sometimes as much as sixty feet. It is much disturbed by faults, but these do not interfere with its being readily and extensively worked. 364 DURATION OP COAL IN ENGLAND. It may perhaps be expected that I should not quit the subject of coal without, at all events, making some allusion to the much debated question of the extent of workable coal still remaining, and the prospect of its speedy exhaustion. I confess, however, that I am unwilling to add any specula- tions of my own to the somewhat unsatisfactory conjectures that have been offered on the subject, many of them by Geologists who deservedly rank among the most distin- guished cultivators of the science. It has been assumed, indeed, that if the supply continues as large as at present, and from the same mines, provided also that an equally small proportion of the whole coal is obtained, and provided also, we may add, that the price does not materially change, and the waste continues : that all thjese conditions being fulfilled, England may find, some few centuries hence, that her northern counties are drained of this most valuable of her mineral treasures. But we may fairly ask, are these con- ditions at all reasonable ? We have already seen that Eng- land is not the only country in the world provided with coal, and there will therefore be competition, and a check thus given to the great consumption from our own mines as soon as they begin to exhibit symptoms of failing. It is said, that the Tyne portion of the northern coal-field is already begin- ning to be exhausted of the finer kinds of coal, and that the hitherto less worked mines of the Wear and the Tees, have an advantage in commercial competition. And this is only what might be expected. So long as any district affords at once the best and the most convenient supply, it will be worked with the greatest energy, but when it begins to be exhausted, others, before thought inferior, immediately take its place. The great coal-fields of Wales are still almost untouched. Must they not ultimately yield a large pro- portion of the supply ; and will not such a change take DURATION OF COAL IN ENGLAND. 365 place gradually, and arrange itself strictly according to the nature of the demand ? And even the American mines will doubtless be called on to assist, as soon as the price of their coal can be so far reduced as to compete with that of ours. I confess it seems to me but a vain thing to attempt any calculation as to the duration of our mineral treasures, as it is a problem for the solution of which there can be no sufficient data. Nor, indeed, can I perceive what useful object is to be gained by the endeavour to make out how many hundred years England may exist, assuming, as it is not unusual to do, that the source of the greatness she has attained is to be looked for in her mineral riches, and chiefly in her large supplies of coal. I am convinced that it is not to the possession of coal or iron, but to the energetic habits of her people, who make the best use of these advantages, that England owes her greatness ; and I believe that her resources are strictly within herself, and that so long as her sons press forward in the race, and are earnestly deter- mined not to lose, without a struggle, the high position they have attained amongst nations, so long will she con- tinue fertile in resources, and constantly communicate fresh supplies of life and energy.* * I venture to offer these remarks, not only with reference to such views as they are generally current, but because expression has been given them in the South Shields Report, already alluded to, in a manner which I think extremely prejudicial to the fair discussion of many economical questions (and some political ones) connected with the subject. The passage alluded to is the following : " Their exhaustion," speaking of the coal-mines of Britain, " or the cheaper ex- traction of coal in another country, would bring with it serious injury, if not ruin : every principle of national superiority in her manufacturing and commercial great- ness, of which they are the spring of action, would be lost." See Report, &c. p. 3. I confess I do not at all agree with this melancholy prospect ; and I think it might easily be proved that it is to the national character of the English people, at least as much as to the existence of valuable coal and iron mines, that her greatness is truly owing. 366 CHAPTER VII. ON THE ACCIDENTS THAT HAPPEN IN COAL-MINES. VENTILATION, SAFETY LAMPS, AND OTHER MEANS OF DIMINISHING THE DANGER. THAT, in the extensive underground works described in the preceding chapters, there should be many casualties and dangers from which men working at their ordinary occupations on the surface are free, can hardly excite aston- ishment, nor would such occasional accidents call for any special notice were not some of them produced by causes in other respects deserving of careful investigation. Some of these accidents, however, possess a painful interest pe- culiarly their own, both because of their fearful nature and their frequent recurrence, and it is right that every one should know, while he is enjoying the luxury of his fire- side, on the possession of which, as an Englishman, he might be inclined to pride himself, that, if he proceeds to examine the circumstances under which the coal is extract- ed from the bowels of the earth, he will discover a vast amount of human suffering and misery necessarily involved before the material can be obtained, upon the due supply of which his comforts so mainly depend. The cause of the chief of these accidents, namely, the presence of a gas in coal-mines, which becomes explosible on being mixed with a certain proportion of atmospheric air, has been already adverted to in the preceding chapter, ACCIDENTS IN COAL-MINES. 367 and I have also there enlarged at some length on those methods of ventilating the works of a mine which seem best adapted to avoid the risk thus inevitably incurred. In spite, however, of the most perfect system of ventilation, it appears quite impossible to prevent the occasional accu- mulation of large quantities of this dangerous gas, more es- pecially in some mines, and some parts of a mine, so that contrivances are necessary, by the help of which even these dangerous parts may be at all events traversed without the risk of an explosion. This necessity was long ago felt, and early in the last century a Mr. Spedding is said to have invented the " steel mill," by which a stream of sparks was produced from the rapid revolution of a rim of steel against flint, and this was supposed to do away with the danger of explosion. Other contrivances succeeded this, but it was not till about the year 1813 that any decided and successful attempt seems to have been made to invent a safety-lamp^ or in other words, a lamp that could be safely trusted in an explosive mixture of gases.* In 1815, Sir Humphrey Davy visited the Wallsend Colliery, to investigate the nature and cause of a number of lamentable accidents that had recently taken place, and the results of this visit, and the circumstances attend- ing it, are thus stated by Mr. Buddie in his evidence before a Committee of the House of Commons in 1835 : " I explained to him as well as I was able," Mr. Buddie observes, "the nature of our fiery mines, and that the * The proportion of carburetted hydrogen gas, or fire-damp, necessary to be mixed with atmospheric air, in order to render it explosible, is about one four- teenth part. With this admixture there is danger, and the danger increases as more fire-damp is added, until the mixture reaches its maximum of explosibility, at which time the proportion varies from one-ninth to one-eighth. The risk of explosion is not so great when there is a larger quantity of the noxious gas, and when as much as one-fourth part of the mixture is composed of it, it will no longer explode, but begins to be inflammable. 368 ACCIDENTS IN COAL-MINES. great desideratum was a light that could be safely used in an explosive mixture. I had not the slightest idea myself of ever seeing such a thing accomplished. After a great deal of conversation with Sir H. Davy, and he making himself perfectly acquainted with the nature of our mines and what was wanted, just as we were parting he looked at me and said, ' I think I can do something for you. 1 Thinking it was too much ever to be achieved, I gave him a look of incredulity : at the moment it was beyond my comprehension. However, smiling, he said, ' Do not despair ; I think I can do something for you in a very short time.'' To the best of my recollection, within fourteen days he wrote to me to say that he had made a discovery which would answer my object, namely, the procuring a safe light in an explosive mixture. In a few days he sent me down two of the Davy lamps, nearly like those at present used. On the strength of his autho- rity, I took the lamp, tried it first in an explosive mixture on the surface, and then took it into a mine, and it is impossible for me to express my astonishment and delight when I first suspended the lamp in the mine, and saw it red-hot. If it had been a monster destroyed I could not have felt more exultation than I did. I said to those around me, ' We have at last subdued the monster. 1 " But alas ! the monster was far from being destroyed, and the very confidence so naturally felt, in a contrivance which seemed to answer every purpose of safety, was only the cause of additional accidents in which the fire-damp triumphed yet more signally than ever.* * It is a melancholy, but unquestionable fact, that the number of accidents from fire-damp since the introduction of the Davy-lamp have been many more in a given number of years than before that invention. This has, no doubt, partly arisen from the larger number of persons employed on the whole ; but it is to be feared that it has chiefly happened from dangerous portions of a mine being taken into work, DAVY-LAMP. 369 The principles involved in the construction of the Davy- lamp are very curious, namely, first, that no mixture of the fire-damp with common air, however dangerous, can be made to explode in tubes, the diameter of which is less than about one-eighth of an inch ; and, secondly, that these explosive mixtures require a much stronger heat for their explosion than mixtures of common inflammable gas, since neither charcoal nor iron, when red-hot, will produce this effect (for which purpose, indeed, iron must be raised to a white-heat). Pursuing this discovery, Sir H. Davy found that the length of the small tubes, in which it was impossible to explode dangerous gases, was a matter of indifference, and that a metallic gauze, in which this length was merely the thickness of a fine wire, was quite sufficient for the purpose. It will be evident, therefore, that by surrounding the light of a lamp entirely by wire gauze whose meshes are sufficiently small, the flame of the lamp will be protected from the effects of an explosive mixture ; the mixture will not be fired, and such a lamp may be safely carried where, otherwise, approach would be impossible. The size of the mesh for this purpose is from one-fortieth to one-sixtieth of an inch, and twenty-eight wires, or 784 apertures to the square-inch, are found a defence perfectly sufficient. It should, however, be distinctly understood that even such a lamp may not be used carelessly in any dangerous atmo- which, without the Davy, could not have been attempted, and partly also from the extreme and culpable carelessness of the workmen in removing the wire- gauze, their only protection, and working with an open flame, in spite of every precaution. It cannot be stated too strongly, that ventilation, and not improvement in the method of lighting, should alone be looked upon as the means of safety. The safety-lamp is invaluable for those whose duties oblige them to traverse the wastes, and direct and superintend the ventilation, and in some doubtful cases even for the hewers ; but it ought not to be depended on for more than this. VOL. II. 2 B 370 DAVY-LAMP. sphere, for, although perfectly secure when at rest, it seems certain that the rapid motion communicated by the swing of the arm during a hurried transit through the mine, might produce, and probably has, in many cases, produced an explosion. The annexed diagram represents the form of the lamp in most general use. Several improvements and altera- tions, some of them exceedingly in- genious, have been suggested to in- crease the safety of this valuable contrivance. It is not, however, too much to say that, while most of these are theoretically much more perfect, they are also more readily injured, and are in every sense less practical. The main fault of the Davy-lamp, and indeed of all the other safety-lamps, arises from the small quantity of light it diffuses, and the consequent dislike acquired by the miners to its use. No contrivance, however perfect, can by possibility exclude the chance of accident, and the gross, and almost inconceivable carelessness of men whose daily occupation leads them into the most imminent danger cannot be overcome, and can with great difficulty be understood by those not in the habit of constant communication with them.* The quantity of carburetted hydrogen gas poured out into the workings of some mines is very considerable and constantly varying. Some seams of coal are much more full of gas than others, and in working these, which are * Very remarkable instances of this obstinate and blind perversity are on re- cord ; and in some instances, where danger has been evident and imminent, the workmen have been known to insist on removing the gauze, in spite even of the remonstrances of their companions. DAVY-LAMP. JETS OF GAS IN FIERY SEAMS. 371 technically called fiery seams, it is not uncommon for a jet of inflammable air to issue out at every hole made for the reception of the gunpowder previously to blasting. In the celebrated Wallsend Colliery, in an attempt made to work the Bensham seam (an attempt terminated by a fearful accident) Mr. Buddie says, in evidence before a Committee of the House of Commons,* " I simply drilled a hole into the solid coal and stuck a tin pipe into the aperture, sur- rounded it with clay and lighted it, and I had immediately a gas light ; the quantity evolved from the coal was such that in every one of those places I had nothing to do but to set a candle and then could set a thousand fissures on fire ; the whole face of the working was a gas pipe from every pore of the coal." But besides the gas thus steadily and constantly forced into the workings of a mine by a fiery seam of coal, there is always danger of sudden discharges as if from great re- servoirs, rushing out from some fissure or small opening in immense quantity and with considerable noise. These jets are met with in mines perfectly ventilated, and they occur sometimes from the roof, sometimes from the floor of the mine. Several collieries in the north of England are remarkable for constant discharges of this kind, which are collected and conveyed by a tube the near- est way to the upcast shaft. It would appear, indeed, that coal parts with a portion of its carburetted hydrogen gas or fire-damp when newly exposed to the atmosphere, and this fact explains the cir- cumstance of the coal being more inflammable when fresh from the pit, than after long exposure to the air. But besides such gradual and constant emission of noxious gas, * Parliamentary Report. Accidents in Mines, 1835 ; Minutes of Evidence, Qu. 2095. 2B2 372 CHOKE-DAMP. the jets, or blowers, as they are technically called, have often been known to continue in activity for many months or even years together, crevices or fissures in the coal or shale pouring out several hundred hogsheads of fire-damp per minute.* This phenomenon clearly shews that the car- buretted hydrogen must have existed in the cavities of the strata in a very highly-compressed, if not actually in a liquid state, and on the diminution of pressure has resumed its elastic form. Breaking into old workings is likewise a fruitful source of mischief, these spaces serving as reser- voirs in which the explosive mixture collects, and is preserved.-)- Not only the fire-damp, but some other noxious gases are occasionally met with in coal-mines. Among these the most remarkable is the choke-damp or Uack-damp, which is the name given by miners to carbonic acid gas, and this gas is often found in large quantities in old workings, more es- pecially in the Lancashire mines. Unlike the fire-damp, whose specific gravity is very much less than that of com- mon air (0*5382) and which tends to rise to the surface, this gas rests on the floor of the mine, and gradually accu- mulates, having no tendency to escape beyond a slow mixture which takes place with atmospheric air. Its spe- cific gravity is 1*5277. But there is another, and more dangerous poison, which has till lately been almost neglected, but the existence * An instance of this occurs near Wallsend church, where about four acres of very fiery coal, worked at a depth of about one hundred and fifty fathoms, are drained as it were of gas by a four-inch pipe, which is carried to the surface, and above the chimney, and there ignited. A fiery streamer, of from eight to nine feet in length, is thus constantly kept burning, and the rush of gas through the orifice roars like a blast-furnace. Not less than eleven thousand hogsheads of gas per minute form the average supply collected from these four acres of coal. See the vignette at the end of this chapter. f Paris' Life of Sir H. Davy, vol. ii. p. 62. OLEF1ANT GAS. 373 of which, as it is nearly of the weight of common air, (sp. gr. 0'9722) and explodes at a lower temperature than ordinary fire-damp, should be known to all those who are in any way concerned with coal-mining operations. I allude to what is sometimes called olefiant gas, or the heavy carburetted hydrogen, which differs in chemical composi- tion from the lighter and more common carburetted hydro- gen by the addition of another proportion of carbon. The presence of this gas was suspected by Davy, and its existence has been proved by Professor Bischof in some of the continental mines, in one instance to the extent of 16 per cent.* Sulphuretted hydrogen is also sometimes present in mines, and may be the source of mischief, as it readily takes fire when iron, at a red-heat, is exposed in it. The Davy-lamp, therefore, in cases where the ordinary fire- damp would be innoxious, may occasionally be the cause of an explosion if either of these two gases is mixed with the fire-damp, and since the indications of their presence, at least with respect to the former, must ne- cessarijy be very imperfect, the danger is of course the greater. Most of these gases when diluted with a mode- rate proportion of atmospheric air, are, although injurious in their effects when breathed, not immediately fatal. Their presence may often be determined much more clearly by the effect they produce on the lamp, than by any impediment they offer to breathing, and thus it happens that on the one hand a dependance far beyond that which is due is often placed upon this contrivance, while on the other hand its proper warning is neglected, and until the meshes which surround * Olefiant gas, when mixed with such proportions of common air as to render it explosive, is fired both by charcoal and iron heated to a dull red-heat. Explo- sive mixtures of sulphuretted hydrogen also are fired by red-hot iron and charcoal. 374 ACCIDENTS FROM FIRE-DAMP. the flame are seen to attain a red-heat, the flame itself having been long dull and obscure, no precautions are taken, and no escape from the dangerous vicinity is con- templated. The miner works on in his gloomy cell regard- less of the destruction that hovers over him, but when it comes it involves not only himself but all those imme- diately about him, and too often its effects are yet more melancholy, dooming to a protracted, and comparatively lingering death, many others in distant parts of the mine. But it is worth while to narrate at somewhat greater length the particulars of one or two of these' accidents, from the circumstances attending which some idea of their cause may be obtained. One of the proximate causes of explosion in workings known to be fiery, is said to be a sudden change in the weight of the atmosphere, indicated by the fall of the barometer. A considerable amount of pressure being thus suddenly ab- stracted from the surface of the coal, an increased quantity of inflammable gas is discharged, and the mixture with common air takes place rapidly and becomes immediately explosible. To this cause is assigned an accident that occurred in the Bensham seam, worked in the Walls- end colliery in 1821, on which occasion fifty- two lives were lost. The workings of this pit were subject to be very con- stantly charged with gas to the firing point ; the ventilation had been for some time under the superintendence of two young men, the overmen, whose vigilance had always been successful in preventing any kind of accident. In consequence, however, of the dangerous nature of the pit, it was placed under the care of the most experienced overman in the colliery, and a short time afterwards the explosion took place, but as the overman, and nearly all J ARROW COLLIERY. 3? 5 those with him in the pit at the time perished, the imme- diate cause of the accident could not be distinctly ascer- tained. At the time of the accident the barometer had fallen suddenly, and stood at 28' 8 inches ; and it has been remarked as generally observable, that the discharge of inflammable air from the fissures in the roof or floor of a mine diminishes when the barometer is rising, and that the jets of gas, or blowers, already described, are much more intense and powerful when the wind blows from the S.E., and the barometer is low.* A very fertile source of accidents in mines is the unex- pected arrival at a fault in working, and this is more par- ticularly the case when the fault is connected with a cavity. Great danger then arises if the cavity is filled with inflammable air, as the suddenness and great force of the eruption and explosion gives no warning for the escape of the colliers, or for allowing the person in charge of the ventilation to adopt the necessary measures of pre- caution. An occurrence of this kind is called by the col- liers c meeting with a bag of foulness? and an accident occurred on the 3rd of August, 1830, in the Jarrow colliery, owing to the bursting out of one of these lags of foulness from a cavity suddenly met with in the workings. The accuracy and minuteness with which this accident and its cause have been described, render it one of painful interest. It proved fatal to forty-one persons. I have subjoined a plan of the works at the time. The Jarrow pit is sunk to the Bensham seam, which is worked at 175 fathoms. The seam is nearly horizontal for 176 yards south of the shaft, but is then dislocated by a succession of faults, till it is ultimately settled at a depres- * Trans, of Nat. Hist. Soc. of Northumberland, vol. i. p. 185. 376 ACCIDENTS FROM FIRE-DAMP. sion of twelve fathoms. The pit is situated 360 yards from the river Tyne on its southern bank. m PLAN OF THE WORKINGS AT THE JABROW PIT AT THE TIME OF THE EXPLOSION, 3RD. AUG 1830. A, Winning headway. r>. Fault, beyond which the fire did not penetrate. B, West workings. E, Fault, cutting off the west workings. c. Fault downcast to the East, the origin of the accident. The existence of the faults mentioned above was well known from the working of the main coal, and the lower or Bensham seam having been fiery on the north or upper side of the faulty ground, was expected to prove at least equally so on the other side. In prosecuting the works, however, very little inflammable air appeared, either in the coal or in a small set of dykes discovered to the south of the faults. About five or six weeks before the time of the accident, a slight discharge of gas was observed, but it did not increase so much as to become dangerous. The whole tract of workings was limited in extent, and the ventilation perfectly good. J ARROW COLLIERY. 377 At 5 o'clock on the morning of the accident, the mine was visited by the resident viewer and the under- viewer, and the overman reported to them that ' a bag of foulness ' had come off in the east drift, (at c in the plan,) but was soon exhausted, and the place had become ' clean.' The overman's account was, that proceeding to the spot, he found the hewer had come upon a hitch-, (a small fault not exceeding in amount the thickness of the seam,) and that bearing in mind the former escape of foul air, he expected that another and similar discharge would ensue, and him- self laid bare more than a square foot of the face of the fault to examine the circumstances connected with it. He then went into the fore drift, examined the state of the ventilation there, and finding it satisfactory, waited about, until, at the usual time, he repaired to a distant part of the mine, where he expected to meet the viewer and under- viewer, and on their arrival he made his report as above. After receiving the overman's report, the whole party proceeded into the first division of the west workings, and were just proceeding to measure off work their object in the mine when they were alarmed by a sudden concus- sion, and whizzing in the air, the well-known indications of an explosion having taken place. Their first impression was, that the accident had happened in a part of the colliery where the pillars were being worked out, distant more than a mile from the place where the explosion really happened. The people who were working at this very spot were also alarmed at the concussion, though at so great a distance. The first care of the viewers was to collect all the men and boys of that (the west) division of the workings into a group, and endeavour to conduct them safely to the bottom of the pit. At a certain point, however, marked in the 378 ACCIDENTS FROM FIRE-DAMP. plan by a shaded portion of the gallery, they were met by the after-damp, and their further progress was thus checked. Knowing that their lives depended on their being able to force their way through this deadly cloud, they threw themselves upon their hands and knees, stuffed their handkerchiefs into their mouths and scrambled away with all possible expedition, till at the distance of about 120 yards they happily met with the full current of fresh air from the bottom of the pit. They knew by this that the ventilation towards the bottom of the pit had been no further disturbed, and as soon as they had recovered their strength by breathing the fresh air, they began to examine into the state of the adjacent parts of the mine. It was at once seen, that all who might have escaped death from the explosion, must inevitably be suffocated unless the current of fresh air could be immediately forced through the main drift (in which they were), to relieve them. All those, therefore, who had escaped, set to work immediately to put up temporary stoppings, in place of those that had been destroyed, and in this way, if possible, restore the current. As soon as this was done, the strongest of the relieving party were enabled to push forward for some distance, until they were again stopped by the heat and the after-damp. It was then but too evident that none of the persons em- ployed in the workings to the east could be living, and as at this point it was also necessary to repair other stoppings before the party could proceed, a number of those in the west workings, who might otherwise have been saved, died from suffocation. The ventilation was now partially restored, and the workings became approachable. It was found that the effect of the explosion had not reached beyond a four-feet downcast fault to the south, and four men working on the JARROW COLLIERY. 379 other side of that fault escaped uninjured. Although the accident happened at about half-past 6 o'clock in the morning, it was not until four in the afternoon that the ventilation was restored in the east workings, and the dead bodies of those who had perished in that quarter were dis- covered. CADSE OF EXPLOSION IN JARROW PIT ILLUSTRATED. At five o'clock in the afternoon Mr. Buddie visited the mine, and proceeded to examine the workings. On reach- ing the part where the accident happened (the face of the drift, marked B in the annexed diagram,) there was no ap- pearance of inflammable air, but the part laid open by the hewer looked as if an old working had been reached, from which a burst of compressed inflammable air had taken place. The drift was nine feet wide, and five feet high, and the whole block of coal forming the face (weigh- ing about six tons) had been forced forward with great violence, having a jagged-edged aperture on two sides, where it had evidently been detached by some enormous explosive force, leaving a hollow space behind. On re- moving the mass of coal the cause of the accident was manifest, there being a space of seven feet behind it ex- tending to a small fault and filled with disintegrated coal * marked (A) in the diagram. * This disintegrated coal in the cavity did not seem to have undergone any 380 ACCIDENTS FROM FIRE-DAMP. In this case, therefore, it was evident that a quantity of inflammable air had been contained in a cavity in the vicinity of a hitch, or small fault, and in a state of high compression. It appears, also, that the coal being worked away till the remaining part was no longer able to resist the elastic force of the compressed gas, the gas had escaped with a sort of explosion and filled the adjoining works, and then, as soon as it was sufficiently diluted with atmospheric air, it took fire at the nearest light, and the explosion occurred. No fire had reached the actual face of the drift, nor, indeed, any spot within eight yards of it, and a man working in the drift parallel to and cor- responding with the one in which the explosion occurred, and similarly situated with regard to the fault, was suffo- cated by the after-damp, but not at all burnt. It is lamentable to find that, from the account of this accident given at the inquest, several premonitory symp- toms had been noticed by one of the workmen, but had not been reported by him to the overman. If these had been attended to, and the face of the coal bored for some distance, always in advance of the drift, the gas would have been tapped by these bore-holes and gradually dis- charged before any risk could be incurred.* I have given in some detail the account of this accident, because there are few instances on record in which the history of the explosion is so clear and complete, or which offers more useful matter for contemplation. In most cases of the same kind, it is the melancholy details of individual suffering which attract attention, rather than that calm consideration of the causes that may have led to the acci- chemical change, "but merely to have been crushed by the force which disturbed the strata, and produced the fault. * Trans. Nat. Hist. Soc. of Northumb., vol. i. p. 187, et seq. FELLING COLLIERY. 381 dent, from which alone can be derived any useful hints for future guidance. The accident which I have just described, in the Jar- row pit, was what is technically called a smart fire, in contradistinction to a heavy one ; the injury done to the mine being trifling, and the fire of small extent, though extremely fatal in its consequences. I now proceed to give a short account of a heavy fire, which took place about thirty years ago, just before the discovery of the Davy-lamp, in the Felling colliery; the colliery being at that time looked upon as a model of perfection for ventilation, and comfort in working. On the 25th of May, 1812, the inhabitants of the villages near this colliery, were alarmed by a tremendous explo- sion. A slight trembling, as if from an earthquake, was felt throughout a circuit of about half a mile round the workings, and a dull sound of the explosion was heard three or four miles off. Immense quantities of dust and powdered coal rose high in the air, and being blown by a strong west wind, fell in continued showers, and even darkened the air to the distance of a mile and a half from the pit, covering the roads so completely that the foosteps of passengers were strongly impressed in it. This fearful announcement to the neighbourhood, that an ac- cident had occurred from fire-damp, was answered by an immediate rush of the wives and children of the col- liers to the mouth of the working pit, and a crowd rapidly collected to the number of several hundreds of persons. The machine was soon found to have been rendered useless by the explosion, but the rope of the gin (a ma- chine consisting of a drum on a vertical shaft, usually turned by a horse, and used for lowering the workmen and raising the coal) was soon sent down to enable those 382 ACCIDENTS FROM FIRE-DAMP. who might have escaped the effects of the accident to ascend to the surface. In rendering this assistance the men put their shoulders to the shafts of the gin, doing the work of horses, and by means of great exertion, thirty- two persons were soon brought out alive, and besides them the dead bodies of two boys. Of these thirty- two, three died in the course of a few hours ; and the remaining twenty-nine were the only survivors out of a hundred and twenty-one human beings at work in the mine at the time of the explosion. As soon as it was possible, with any prospect of safety, nine courageous individuals descended, taking with them steel-mills, at that time the only contrivance known for obtaining light in dangerous workings, but their progress was soon interrupted by the after-damp, and the sparks from the mill fell into this noxious gas like drops of blood. Deprived of light, and nearly poisoned for want of air, they were obliged to retrace their steps towards the shaft, and then attempted to advance in another direction ; but here, also, they were soon stopped by thick smoke, which stood like a wall before them, filling the whole height of the gallery and effectually barring their pas- They returned with difficulty to the pit bottom, under the full conviction that the mine was on fire ; and before all of them had time to ascend, another explosion took place, the men still at the bottom only saving themselves by lying down with their faces to the ground. Under these circumstances, it was quite clear that all prospect of saving any of the persons remaining in the pit was perfectly hopeless, and the only mode of extin- guishing the fire was by closing the pit, and excluding the atmospheric air ; but to this many objections were FELLING COLLIERY. 383 urged by the friends of the unhappy sufferers, and com- plaints were made of want of proper exertion on the part of the owners ; but they being convinced that the workings were quite unapproachable, refused to offer any reward or inducement to enter the mine. One more attempt was, however, made to proceed from the shaft towards the workings, but it proved equally unsuccessful ; and now the smoke issuing from the pit mouth gave such unequivocal proof that the mine was fired, that without further delay the air was excluded, the mouth of the pit being completely closed up. This happened on the 26th of May. Six weeks afterwards the pit was re- opened, and in a few days the ventilation was sufficiently restored to allow of the workmen entering the drifts. On the 8th of July, everything being prepared for the work, nine men descended, and made their way, lighted by steel-mills, in search of the bodies of the unhappy sufferers in the accident. The bodies, mostly in a shock- ing state of decomposition, were all recovered but one ; and all, with the exception of four, were buried side by side, in one trench, in He worth chapel yard, where an obelisk was afterwards raised over this immense grave, on which the names and ages of the sufferers were recorded. The ventilation was not sufficiently restored to admit of the working of the mine before the J9th of September, and in little more than a year from that time another explosion took place in the same mine, killing twenty- three, and severely burning thirteen persons. The mine was intersected with several dykes and fissures, which not unfrequently discharged great quan- tities of inflammable air from the roofs and floors of the galleries ; but it was never satisfactorily proved whether the accident was owing to the falling in of some 384 ACCIDENTS FROM THE IRRUPTION OF WATER. matter in the wastes, interfering with the regular course of the ventilation, or whether, by some neglect, the furnace was not acting properly at the bottom of the upcast pit. The general condition of the ventilation was so good, that the workmen declared they never wrought in a pit so wholesome and pleasant. But terrible as the danger is, and fearrul as are the accidents resulting from the presence of inflammable air in coal-mines, these dangers are not the only ones that must be braved by the pitman in his underground work, and in many cases he is exposed to accident from water as well as fire. As an instance of this, in the year 1815, seventy-five persons were drowned in the Heaton Main colliery; the old workings of another colliery, in which the water had accumulated, rushing into the works, which were carried on in ignorance of the proximity of these old mines. Acci- dents of this kind have also frequently happened in other coal-fields, and it is only a very few years since one of the principal collieries of Whitehaven, carried on under the bed of the ocean, was suddenly and completely de- stroyed by the incursion of the sea into the workings. One of the most interesting of the accidents of this kind on record occurred in 1833, in an extensive Scotch colliery, of which the workings were so much injured by the irruption of a river into them, as to be afterwards almost useless. On the 20th of June, in the year above mentioned, two gentlemen fishing in the river Garnock, observed nearly opposite to where they were standing a slight eruption, which they supposed at first was occasioned by the leap of a salmon ; but a gurgling noise which succeeded, led them to suspect that the water had broken SCOTCH COLLIERY. 385 into one of the coal-mines surrounding the spot. With this idea they hastened to the nearest pit mouth to give warning ; but their notice was neglected, as too impro- bable to be worth attending to. Before very long the workmen were found to be making their way to the bottom of the shaft, several of them being up to their necks in water when they reached it. All of them, however, escaped with life, and as soon as they reached the surface they proceeded at once to check, if possible, the rush of water into the mine, by filling the cavity in the bed of the river with straw, clay, Sec. ; but their efforts were vain, for the water continued to pour in steadily till the following afternoon, when a large space of the bed of the river was broken through, and the whole body of the stream was in a short time engulphed, its bed being left dry for more than a mile. The river was affected by the tides, and this engulphrnent took place at low water, but as the tide rose, the sea entered with prodigious force, and the sight was impressive be- yond description, the water continuing to pour in till the whole workings, extending for many miles, were complete- ly filled, and the river resumed its ordinary appearance. No sooner, however, had this taken place, than the pressure of the water in the pits became so great, that the confined air, which had been forced back into the high workings, burst through the surface of the earth in a thousand places, and many acres of ground were seen to bubble up like the boiling of a cauldron. Great quantities of sand and water were also thrown up, like showers of rain, during a period of five hours, and an extensive tract of land was laid under water, by which from five to six hundred persons were entirely deprived of employment. VOL. II. 2 C 386 ACCIDENTS IN COAL-MINES. Many other accidents occur besides these of fire and water, and some of them are occasionally fatal ; but as they are, for the most part, dependant on local cir- cumstances, and must be looked on rather as ordinary casualties, which, however melancholy, can not be entirely prevented, and belong more or less to all kinds of em- ployment, I shall not here detain the reader by dwelling upon them. Those connected with the imperfection of machinery, such as the bursting of steam-boilers, the breaking of ropes, disarrangement of the winding ma- chinery, and others, are gradually becoming fewer, and with proper care may be reduced to a very small num- ber ; but so long as coal-mines continue to be worked, so long will there be a succession of victims to the fire-damp, a 'monster' which no art of man is ever likely to render harmless. The fiery seams, if they must be worked, cannot be worked without danger, and the extent of this risk it is truly painful to contemplate, for it appears that, in the southern part of the Newcastle coal-field alone, nearly seven hundred miners have met with death by explosions of fire-damp within the last twenty years. Some sympathy is certainly due, then, to that large class of our fellow-subjects, who contribute so painfully to our comforts and enjoyments ; and, with reference to this subject, I may appropriately quote the following re- marks on the accidents of coal-mining, from the Report of the South Shields Committee, already more than once referred to. " Pit coal," it is there said, " is produced by a seve- rity of labour and risk of personal safety to the miner, which the workman of no other occupation is ex- posed to. ACCIDENTS IN COAL-MINES. 387 " The pitman descends 200, 300, and sometimes more than 500 yards into the bowels of the earth, and there traverses subterranean passages, frequently from two to three miles in extent, to his work ; where by the glim- mering of a small candle, or more imperfect lamp, in a space seldom six feet high, and oftener three or four, he labours in a stooping posture, sometimes lying on his side for eight or ten hours together, in an impure atmo- sphere, to extract the mineral that aboveground is dif- fusing light, heat, riches, and enjoyment. " In such a situation, often without a moment's warning, he is overtaken by destruction. The gases generated in such abundance in the mine, from some accident suddenly explode, and fill the pit with death. In an instant, and in the most fearful manner, he is scorched and shrivelled to a blackened mass, or is literally shattered to pieces against the rugged sides of the mine ; or, if out of the immediate range of this terrible piece of ordnance, in a few seconds the after-damp spreads itself in every direction, and poisons beyond recovery all that it may reach. Humanity has too frequently to deplore these fearful accidents."* That these accidents are most deeply to be lamented there cannot of course be one moment's question, and the only matter that remains for consideration is whether by any legislative measure, or by any application of human in- genuity in the arrangement of the workings, some greater degree of safety cannot be introduced, and some portion at least of this fearful destruction of human life be checked. One thing at any rate is certain, and it cannot be too often repeated, or brought too frequently under the con- sideration of the owners of coal property, namely, that * Report, &c., p. 3. 2c2 388 ACCIDENTS IN COAL-MINES. greater security must not be looked for by any .kind of lamp that may be contrived, but in the improvements that may be effected in the ventilation of the mines. This is the only real principle of safety, for this is the only possible means of rendering harmless the noxious air given out in such abundance beneath the surface of the earth. There are, however, doubtless many practical difficulties in the way of increasing the quantity of fresh air in a mine, and these are greater as the mine is deeper and more extensive and the property more valuable, but it does seem, from the evidence of unprejudiced persons, that in many cases the extent of air-passages, ventilated by a single shaft, is far greater than it ought to be, and greater than will admit the possibility of effectual control. That this is no exaggeration, appears from the evidence adduced in the South Shields Committee Report,* where it is stated that in one instance only, a single pit of thirteen-and-a-half feet diameter is allowed for the ventila- tion of between seventy and seventy-five miles of passages, the pit being used besides for drawing the coals and pump- ing water. This pit is eight hundred and fifty feet deep ; the mine is worked to the extent of four hundred acres, and the supply of air moves only at an average rate of one- and-one -tenth foot per second through considerably more than one-half the mine. Several other instances even more striking, are quoted in the Report from which these details are obtained, and it seems only reasonable to as- sume, that while such a condition of the deeper and more extensive mines is allowed to continue, those means are not taken which alone can justify the owners of the pro- perty in working mines known to contain a large quantity of noxious and dangerous gas. * Report, &c., p. 31. ACCIDENTS IN COAL-MINES. 389 Various methods have been suggested by which the rate of motion of the column of air, made use of to venti- late a mine, may be increased by mechanical contrivances, and it has also been proposed that the area of the upcast shaft, bringing the warmer, and therefore expanded air, to the surface, should be larger than that of the downcast. These methods may well be the subject of inquiry and investigation, but perhaps they have not yet been suffi- ciently matured to be brought into use on a large scale. There will also be a difficulty in inducing the coal-owners and others to introduce them, involving, as they often do, theoretical applications of some principle not generally understood, and being more frequently proposed by specu- lative men, strangers to the actual operations of mining, than by those practical, as well as scientific persons who have an admitted public claim on attention. WALLSEND COLLIERY. 390 CHAPTER VIII. THE MISCELLANEOUS APPLICATION OF MINING PRINCIPLES I IRON-MINES : SALT-WORKS. THE vast preponderance in the value of the iron ahove that of every other metal obtained in England, and even above all of them taken together,* renders it necessary that I should devote some space here to describe the work- ing of those ores from which the supply is chiefly derived ; and I shall also allude shortly to the methods adopted in order to obtain the metal in the state of what is called ' pig. 1 Of the further processes by which it is rendered malle- able, I shall say nothing, as they belong strictly to the subject of metallurgy. The principal districts in the British Isles from which iron is obtained are three, the South Welsh, the South Staffordshire, and the West of Scotland. The beds of ironstone being interstratified with the coal, and the sandstones and shales of the coal-measures, they are usually raised from the same pit as that by which the coal is extracted. The thickness of the ore, however, being generally only a few inches, it is worked in a manner somewhat different. Near Bilston, in the South Staffordshire district, there * It is stated in Sir H. de la Beche's Report of the Geology of Cornwall, that the value of the iron annually obtained from the ores in the United Kingdom may be estimated at eight millions sterling, while that of all the other metals together scarcely exceeds two millions and a half. This amount will be seen to be far less than that given in the table, note, p. 303. It appears, however, that M. Burat has calculated the value of the metals by a different scale. IRONSTONE BANDS. 391 are as many as seven seams containing ironstone, all distin- guished by technical names, but many of them not more than five or six inches in thickness, and alternating with claystones not containing iron. Two of the ironstone bands are thicker and more valuable than the rest, and they, as well as all the others that are worked, lie beneath the ten-yard seam of coal in the district. The seams are, if possible, worked two together, the intermediate stuff being of no value, but removed to form a gallery, and after- wards piled up to support the roof, when the ore has been obtained. , The nature of the work is sufficiently simple ; the miner usually lying on his right side, and striking with the pick to remove the ore and the inter- mediate clay. This method may seem a disagreeable one, but the galleries are cooler than the coal-mines at the same level, although they are also wetter and dirtier. The iron- stone is of a dull brown or yellowish colour ; it very often occurs in the shape of flattened spheroidal balls, and is traversed by cracks and fissures which have become filled with carbonate of lime. The centres of the spheroids often exhibit an organic nucleus. There is considerable danger in working these mines from the occasional falling in of a portion of the roof, but they are usually almost entirely free from noxious gases. The iron district of South Wales supplies a large pro- portion of the whole amount of this metal raised in tjie British Islands. It is identical with the great coal-field of that district, the ironstone bands being always asso- ciated with the various beds which make up the carbo- niferous series. The bands of ironstone here, as in Staffordshire, are usually not more than a few inches thick, and the work- ings are, therefore, as narrow and low as possible. They 392 IRON ORES. are often inclined at a considerable angle, and this posi- tion is taken advantage of by working in levels which com- municate with a lower part of the shaft by galleries run on the dip of the vein. " The distribution of the ore among the limestone, which in the Forest of Dean forms its matrix, is sometimes very remarkable. It lies in 'churns? or 'pockets? as the miners term these deposits ; and as the ore is cut away, natural pillars and arches of limestone are left supporting the roof in a variety of grotesque forms and combinations. The contents of the churns vary both in quality and quantity, producing a picturesque irregularity in the mine-works, strongly contrasting with the even courses of the coal strata." * Accidents are said to happen very frequently in these mines, from the workpeople neglecting to prop up the roof with timbers as they proceed. The iron works in Glamorganshire and Pembrokeshire are sometimes so near the surface as to be obtained with- out a shaft or regular galleries. In other cases, they are worked from an adit level, which comes out to day on the side of a hill. The iron district of Scotland contains a vein of ore, (called the UacJc land,) much richer than any of those met with in South Wales or Staffer dshire.-f- This valu- able stratum is extremely local, not being known to exist in perfection beyond a space of from eight to ten square miles ; but similar deposits of inferior quality are sufficient- ly abundant. Although, however, the true black band is so narrowly * First Report of Commissioners on Mines. Appendix, Pt. ii. p. 4. t It is said that a black band resembling the bed so celebrated in the Scotch iron-works has lately been discovered in South Wales. The effect of this upon the price of Welsh iron will shortly appear if there is any abundance of the ore, and it must, in that case, be very injurious to the Staffordshire works. THE USE OF THE HOT-BLAST. 393 confined in its distribution, there are no less than four principal and valuable seams of ironstone in the Lanark- shire district, three of which are of very superior quality. These measure from fourteen to eighteen inches each in thickness, and when roasted yield from 60 to 70 per cent, of iron, requiring not more than six cwt. of limestone as flux, instead of from twenty to thirty cwt. (as the poorer and less fusible ores do) to produce the ton of metal. The principal circumstance which has given an impulse to the iron-manufacture in Scotland, and consequently caused a most rapid increase in the iron-works in the neighbourhood of Glasgow and elsewhere, is the inven- tion of the hot-blast, but the method of applying a blast of heated air during the smelting of iron ore was progressively developed, and has been gradually gaining ground for many years. The general plan now adopted, not only in Scotland, but in the English iron-mine dis- tricts, is to drive the air from the blowing-cylinders through a number of flattened tubes of iron, arranged within a furnace of brick-work, and the tubes being ren- dered red-hot the blast is made to enter the smelting furnace at a temperature of 600 Fahrenheit a heat somewhat more than sufficient to melt lead. The advan- tages which result from this arrangement are, 1st. A great saving of fuel, as about two and a half tons of raw coal now do as much service as the coke derived from eight tons when used with the cold-blast. 2. The saving in labour and time in doing away with the coking; and 3. Nearly double the quantity of pig iron produced from the furnace in the twenty-four hours. It has, indeed, been considered, that the iron produced in this way by the hot-blast is not economical in the farther processes of reducing it to a malleable state ; but 394 IRON-MAKING. there can be little doubt, that the method will ultimately succeed, and take the place of the cold-blast, in spite of the prejudices that at present exist against it. Let us proceed now to consider shortly the nature of the processes by which the ironstone is converted into the state of metallic iron. Carbonic acid and clay enter very largely into the compo- sition of most of the iron ores used in England, and a small proportion of water, sulphur, silex, and sometimes arsenic and other metallic ingredients are also present. The per centage of iron varies greatly what is generally used containing from 18 to 50 or 55 per cent., while the average may be stated at about from 30 to 35 per cent. The black band, and the other rich ores of Scotland, contain, however, a much larger proportion. The first operation is generally that of roasting, or calcination, performed in kilns, and the object of this is to get rid of the water, sulphur, and other impurities. The roasted ore, sometimes mixed with a portion of richer ore, is afterwards smelted in the blast furnace, being assisted by a certain proportion of limestone, or other sub- stance, which combining with the clay of the ore, and forming with it a fusible compound, runs off during the smelting in a slag or cinder, leaving the iron in a melted state at the bottom of the furnace. In order to obtain this result, the roasted ore is put into a furnace of a pecu- liar shape and construction, with a certain quantity of coke and flux, and is there exposed to an intense heat. A section of the furnace used (called a blast-furnace) is re- presented in the accompanying diagram, and its mode of action is readily explained. The furnace is strongly built round with masonry, and the interior #, (from 14 to 17 feet in diameter in its broadest part), is lined with fire- THE BLAST-FURNACE. 395 SECTION OF A BLAST-FURNACE. a- The Boshes. 6. The Twyeres. bricks, and gradually diminishes in size to the cylinder at the top, called the tunnel head, where its diameter is not more than seven, eight or nine feet. Below the broadest part the dimensions also diminish rapidly, and at length terminate in a small cylindrical or cubical portion called the hearth, the walls of which are provided with recesses for the introduction of the blast. The hearth is either made of coarse grit or of firebrick, and measures about three feet each way. The whole height of such a furnace would be 55 or 60 feet ; but this is a large size, and the furnaces, in many parts of the country, are not nearly so extensive. The furnace being thus contrived, the blast is applied by means of pipes passing into the furnace through holes provided in the hearth called twyeres (tuyeres, tubesj b, see diagram. Sometimes two, but occasionally three twyeres are used, and the management of them requires very con- siderable skill. The blast is produced by powerful steam- engines moving blowing-pistons, and is t regulated by being passed through a closed vessel. 39 6 IRON-MAKING. The furnace being first thoroughly heated, is in a con- dition to receive the materials for smelting, and these con- sist of a due admixture of ore, coke, and flux, from the mutual action of which during combustion the iron is ob- tained. The materials are introduced at the tunnel head by the filler, and the proper number of charges added from time to time, in order to keep the furnace full during twelve hours, at the end of which time the lower part is tapped, a hole being opened on a level with the bottom of the hearth, and in front of the furnace. Besides this aperture, there is also a hole level with the top of the hearth by which the liquid scoria, or cinder, is constantly running off, while the iron sinks down to the bottom. The appearance of the cinder is a very accurate index of the changes going on in the furnace, and generally indicates the quality of the iron that is about to be run out. The iron is run out into furrows prepared in sand, and the semi-cylindrical portions thus obtained are called pigs, the iron in this state being pig-iron. When the running is completed, the hole is stopped up with a mixture of sand and clay, the charges are continued, and the operation goes on without any cessation, the furnace being kept in constant work for months, and the running taking place every twelve hours. The quantity of iron manufactured in the British Isles is greater, perhaps, than could readily be imagined. In the year 1839, the South Welsh district, including the Forest of Dean, produced 533,000 tons, South Stafford- shire 367,000, and Scotland 200,000; so that, including the amount made in other parts of the country, the total produce must have reached one million three hundred and forty-eight thousand tons. In order to obtain this quan- tity of pig-iron, it is calculated that upwards of four mil- ENGLISH IRON. 397 lions of tons of ore, a million and a half tons of limestone, and seven millions of tons of coal, were extracted from the bowels of the earth, and that, at the lowest calcula- tion, the labour of a hundred thousand human beings, be- sides steam-power, was employed in first raising, and then reducing the ore. Besides the supply of iron ore associated with coal in England, a considerable quantity is also obtained in a similar way from the mines in France, Belgium, and North America. In each case the mines have been work- ed with great vigour, and some attempts have been made to rival the English in this great article of export trade. Although, however, every encouragement, even to the laying on of a protective duty to a considerable amount, has been offered by foreign governments, and much iron has accordingly been made, the great advantages possessed by our own country, are of a nature hardly to be injured by fo- reign competition. Our iron ore is situated in those districts where coal is cheapest, the ore itself is sufficiently abundant, the necessary flux is at hand, and fire clay no unimpor- tant article in the building of the furnaces, on whose long- continued working so much depends is found in the same ground as the ore itself. The largest and most complete manufactories have long been established in the most con- venient places and with an almost unlimited amount of capi- tal, the most perfect and the cheapest communication by water is open to all parts of the world ; the further processes which the metal has to undergo are performed at once on the spot, in the best manner and at the smallest possible expense, and nothing can surpass the enterprise of the great iron-masters. Nothing, in short, but English energy and perseverance, with resources such as England only knows, can ever interfere in her iron trade, within certain 398 SALT-MINES. limits of distance and expense of transit. Beyond those limits our trade must always be doubtful, and to a cer- tain extent forced and unnatural. SALT-MINES. THE salt-mines of Cheshire form so legitimate a branch of the great mining operations of our country, that they well deserve notice among the applications of mining principles now under consideration. These mines, and the brine-pits of Worcestershire, not only supply sufficient salt for the consumption of almost the whole of England, but upwards of half a million of tons, for the most part the produce of the neighbouring county of Cheshire, are annually exported from the port of Liverpool. The immense deposits of rock-salt from which this great supply is obtained, are strictly confined in England to the marls of the New red sandstone formation, and they are not universally distributed, but only met with in two or three counties skirting the principality of Wales. In Cheshire the salt occurs in large quantities in the condi- tion of an impure muriate of soda, and associated with a peculiar marl: it is sometimes massive, and sometimes existing in large cubical crystals, and the beds containing it usually alternate with considerable quantities of gypsum or sulphate of lime, although this latter mineral is not worked to profit. The appearance of the rock-salt is by no means of that brilliant character, nor has it the delicate transparency, and bright reflecting surface, which the reader may per- haps suppose characteristic of it. It is usually of a dull red tint, and associated with red and palish green marls ; ROCK SALT OF CHESHIRE. 399 but it is still not without many features of great interest, and when lighted up with numerous candles, the vast sub- terranean halls that have been excavated present an ap- pearance richly repaying any trouble that may have been incurred in visiting them. In Nantwich and the other places in Cheshire where the salt is worked, the beds containing it are reached at a depth of from 50 to 150 yards below the surface. The number of saliferous beds in the district is five, the thin- nest of them being only six inches, but the thickest nearly forty feet thick, and a considerable quantity of salt is also mixed with the marls associated with the purer beds. The method of working the thick beds is not much unlike that already described in speaking of the thick coal-seams of Staffordshire and Shropshire. The roof, however, being more tough, and not so liable to fall, and the noxious gases with the exception of carbonic acid gas totally absent, the works are more simple, and are far more pleasant to visit. Large pillars of various di^ mensions are left to support the roof at irregular intervals, but these bear only a small ratio to the portion of the bed excavated, and rather add to the picturesque effect, in relieving the deep shadows and giving the eye an object on which to rest. The intervening portions are loosened from the rock by blasting, and it may be readily under- stood that the effect of the explosions heard from time to time, and re-echoing through, the wide spaces, and from the distant walls of rock, give a grandeur and im- pressiveness to the scene not often surpassed. The great charm, indeed, on the occasion of a visit to these mines, even when they are illuminated by thousands of lights, is chiefly owing to the gloomy and cavernous appearance, the dim endless perspective, broken by the numerous 400 SALT-MINES. pillars, and the lights, half disclosing and half concealing the deep recesses which are formed and terminated by these monstrous and solid projections. The descent to the mines is by a shaft, used for the general purposes of drainage, ventilation, and lifting the miners and the produce of the mine. The shafts are of large size in the more important works, and the excava- tions very considerable, the part of the bed excavated amounting in some cases to as much as several acres. Over this great space the roof, which is twenty feet above the floor, is supported by pillars, which are not less than fifteen feet thick. The Wilton mine, one of the largest of them, is worked 330 feet below the surface, and from it, and one or two adjacent mines, upwards of 60,000 tons of rock-salt are annually obtained, two-thirds of which are immediately exported, and the rest is dissolved in water, and afterwards reduced to a crystalline state by evapora- ting the solution. The mines, however, are not the only sources from which salt is obtained, and it is only since the year 1670, when the beds were discovered during an unsuccessful sinking for coal, that the actual rock-salt, as a mineral, has been dug out from the mine. Before that time the chief supply was obtained from the brine springs of Droit- wich, near Worcester Among the most remarkable of the rock-salt mines in Europe, are those of Altemonte in Calabria, Halle in the Tyrol, Cardona in the Pyrenees, and Wieliczka in Poland. These are all interesting, and each exhibits phe- nomena peculiar to itself, but I must not detain the reader with an account of individual mines. The deposit of salt in the valley of Cardona, in the Pyrenees, is, however, too remarkable to be passed over. SALT-WORKS OF CARDONA. 401 MASS OF ROCK-SALT. CARDONA IN THE PYRENEES. In this spot two thick masses of rock-salt, apparently united at their bases, make their appearance on one of the slopes of the hill of Cardona. One of the beds, or rather masses, has been worked, and measures about 130 yards by 250, but its depth has not been determined. It con- sists of salt in a laminated condition, and with confused crystallisation. That part which is exposed (see the wood-cut) is composed of eight beds, nearly horizontal, and having a total thickness of fifteen feet, but the beds are separated from one another by red and variegated marls and gypsum. The second mass, not worked, ap- pears to be unstratified, but in other respects resembles the former, and this portion, where it has been exposed to the action of the weather, is steeply scarped, and bristles with needle-like points, so that its appearance has been compared to that of a glacier. Perhaps a better idea of the nature of mines of this kind will be obtained by the following general account of a visit to the Polish salt-mine of Wieliczka, than by dwelling on the details of the workings, which are nearly VOL. II. 2 D 402 SALT-MINES OF POLAND. the same in most cases. This visit took place seventy years ago, and gives, therefore, a picture of the mining contrivances of that date, but little change has taken place up to the present day. The manner of descending into the mine was by means of a large cord wound round a wheel, and worked by a horse ; and the visitor, seated on a small piece of wood placed in the loop of the cord, and grasping the cord with both hands, was let down two hundred feet, the depth of the first galleries, through a shaft about eight feet square, sunk through beds of sand alternating with limestone, gypsum, variegated marls, and calcareous schists. Below the first stage, the descent was by wooden staircases, nine or ten feet wide. In the first gallery is a chapel measuring 30 feet in length, by 24 in breadth and 18 in height, every part of it, the floor, the roof, the columns which sustain the roof ; the altar, the crucifix, and several statues, all cut out of the solid salt. It does not, however, appear that the salt in these mines is purer, or better adapted to produce those magic appearances which have sometimes been ima- gined, than the same mineral as it occurs in the mines of Cheshire. The manner of obtaining the salt in the Polish mines at the time of the visit we are recording was peculiar and ingenious, but has since been partly superseded by the use of gunpowder. In the first place, the overman, or head miner, marked the length, breadth, and thickness of a block he wished to be detached, the size of which was generally the same, namely, about eight feet long, four feet wide, and two feet thick. A certain number of blocks being marked, the work- men began by boring a succession of holes on one side SALT-MINES OF POLAND. 403 from top to bottom of the block, the holes being three inches deep and six inches apart from one another. A horizontal groove was then cut half an inch deep both above and below, and having put into each of the holes an iron wedge, all the wedges were struck with moderate blows, to drive them into the mass. The blows were continued until two cracks appeared, one in the direction of the line of holes, and the other along the upper horizontal line. The block was now loosened and ready to fall, and the workman introduced into the crack produced by the driving of the wedges a wooden ruler, two or three inches broad, and moving it backwards and forwards on the crack, a tearing sound was soon heard, which announced the com- pletion of the work. If proper care had been taken, the block fell unbroken, and was then divided into three or four parts, which were shaped into cylinders for the greater convenience of transport. Each workman was able to work out four such blocks every day, and the whole number of persons employed in the mine, varied from twelve hundred to about two thousand. The mine was worked in galleries, and it was said that, at the time of the visit, the account of which I have just given, the extent of these galleries was at least eight English miles. The excavations are now much more extensive. The method of preparing the rock-salt, and the pro- cesses employed in manufacturing salt from brine springs, is nearly the same in all salt-works. The first process is to obtain a proper strength of brine, either by saturating fresh water with the salt that has been brought up from the mine, or pumping up the salt water from springs that have become saturated by passing through saliferous beds. The brine obtained in a clear state is put into evaporating pans, and brought as quickly as possible to 2 D 2 404 MANUFACTURE OF SALT. a boiling heat, (in the case of strong brine 226 of Fah- renheit,) when a skin is formed on the surface consisting chiefly of impurities. This is taken off, and either thrown away, or used for agricultural purposes, and the first crys- tals which form are likewise raked away and thrown aside as of little value. The heat is then kept up to the boil- ing point for about eight hours, during which time eva- poration goes on steadily, the quantity of liquid becoming gradually reduced, and the salt being deposited. It is then raked out, put into moulds, and placed in a drying stove to render it perfectly dry, and ready for sale. The finer kinds of salt are made by evaporating at a lower temperature, and of course require a longer time to pro- duce ; while a still coarser kind than that obtained by the rapid evaporation of brine, is sometimes made from sea- water and salt-springs, by merely solar evaporation, the water being exposed in large pans, or passed through a succession of frameworks of numerous small twigs, so con- trived as to expose a very large surface to the air. The salt obtained from sea-water is called bay-salt, and pos- sesses many impurities from which the other kinds are free. It may be worth while to mention, that the proportion of salt obtained from strong salt-springs, varies from 3^ to 6^ per cent., but in sea- water does not exceed 1|- per cent. 405 CHAPTER IX. THE MISCELLANEOUS APPLICATION OP MINING PRINCIPLES (C0n- tinued). GYPSUM AND ALABASTER WORKS. ALUM- WORKS. LIGNITE AND BROWN COAL. - QUARRIES AND OPEN WORKINGS. GYPSUM AND ALABASTER. GYPSUM, or sulphate of lime, and the peculiar form of that mineral called Alabaster, are substances of considerable importance in the arts, and possess also a certain amount of interest for the Geologist. Rendered more valuable by a slight admixture of carbonate of lime, the gypsum of Mont- martre, near Paris, has long been celebrated for its excel- lence as a cement when burnt (forming the well-known plaster of Paris). The variegated alabasters of Italy, Der- byshire, and elsewhere, are so ornamental and beautiful as to possess considerable value ; while the pure white varie- ties are employed in the manufacture of porcelain and the glazing with which it is covered ; and the coarser kinds are advantageously used as a top-dressing for many soils. All the different varieties of gypsum, when exposed to heat, are deprived of their water of crystallization, and become opaque, falling into a powder, which, if mixed with water, speedily hardens on subsequent exposure to the air. Marls containing gypsum are found in various geological localities, and are often associated with saliferous beds. The chief deposits of this mineral in England are in the 406 GYPSUM AND ALABASTER. New red sandstone of Cheshire and Derbyshire. In the neighbourhood of Paris, the extensive gypsum beds of Montmartre form an important part of the older Tertiary series of deposits in that locality. In Germany and the Vosges, the beds of the Triassic system (corresponding to the New red sandstone of England) are its chief deposi- taries ; while in Russia, and apparently also in North America, it abounds in the older strata of the Magnesian Limestone, or Permian system. The gypsum of Montmartre is worked chiefly in quarries, and is remarkable for containing in great abundance the fossil remains of quadrupeds. It is found resting on a limestone of marine origin, and forming a range of hills, whose peculiar aspect (resembling elongated cones) may be recognised from a distance. These hills are distinctly superimposed on lower hills of much greater extent. There are two masses of gypsum at Montmartre, the lower of which is composed of beds abounding in selenite, (the crystallized sulphate of lime,) and alternating with finely-laminated argillaceous marls. The upper mass is both the most important and the thickest, attaining in some places a thickness of nearly twenty yards. It con- tains very few marly beds, and in some places appears immediately beneath the vegetable soil, and is readily and conveniently worked without any subterraneous excava- tions. In Derbyshire, as in Italy, the sulphate of lime, taking the form called alabaster, is worked chiefly for the artist, and the manufacture of it in the latter country forms a very important element among the industrial occupations of the people. The finest white varieties are usually selected for statues and busts ; the ordinary variegated kinds are worked into pillars, and other ornaments for the internal ALUM- WORKS. 407 decoration of houses ; and the most beautiful variegated sorts are cut into vases, columns, plates, and other draw- ing-room furniture of an ornamental kind. The neigh- bourhood of Volterra, in Tuscany, contains so great an abundance of this substance as to supply alabaster to most parts of the world. The beds there containing it belong to the Tertiary period, and salt-springs abound in the vicinity of the quarries. ALUM-WORKS. ALUM is a mineral greatly used in the arts, (in the ma- nufacture of leather, paper, &c., and in various processes of dying,) and it occasionally appears in a native state as an efflorescence on the surface of bituminous shale, and various kinds of stones, shales, and earths, which are for that rea- son called alum-shale, alum-stone, alum-earth, &c. These rocks usually contain only the constituent parts of alum, and not the mineral itself; but the constituent parts are greatly disposed to unite, when placed in juxtaposition. It is the object of alum- works to arrange the materials, so that the most favourable circumstances for the formation of the mineral shall be presented ; and a little geological as well as chemical knowledge is necessary, in order to do this to the best advantage. The alum of commerce is a compound salt of alumina and potash (a bi-sulphuret), and therefore requires the pre- sence of its two bases, and some sulphate or sulphuret, which is most usually the sulphuret of iron or iron pyrites. Wherever all these substances are present, and in such a way that the alteration in the combinations can be readily effected, there alum-works may be established. The most ancient and most celebrated alum-works are 408 ALUM-WORKS. those of Bocca (the present Edessa), in Syria ; and hence the alum of commerce is often called Rocca, or jffodk-alum. A sulphate of alumina and potash was afterwards disco- vered among the volcanic rocks of Italy, and from this alum-stone the mineral was for a long time chiefly ob- tained ; but it is now manufactured yet more extensively in our own country and in Germany. The shaly beds containing pyrites, which are found in the upper part of the Lias formation in the north-east of England, have been found extremely convenient for the manufacture of alum, and are commonly called alum-shales. A section of the lias is exposed on the sea- coast of York- shire, near Whitby, and exhibits an extensive range of lofty cliffs, from three to four hundred feet in height. These cliffs are composed of very dark grey beds of slaty clay, lying nearly horizontal, and stretching out at the base into an extensive flat pavement, on which the sea washes, and which is laid bare to a considerable distance at low water. Mingled with this clay is a large quantity of iron pyrites, which is sometimes so abundant, that spontaneous combus- tion takes place when the beds are exposed to atmospheric action. The clay itself is of a silky lustre, and splits very rea- dily into thin laminae, but is sometimes extremely hard when dry. A considerable quantity of jet, which is a peculiar and well-known form of carbon, is found in the shaly beds, and in some parts they are also extremely fossiliferous. The tertiary beds, abounding with lignite, found on the banks of the Rhine, near Bonn, also contain alum-earth, but in a somewhat different condition. In this case, the lignite is remarkable for the quantity of iron pyrites ac- companying it, while the associated clays consist of nearly pure alumina. The mixture of sulphuric acid, alumina, and potash is obtained by burning together the pyritous wood LIGNITE. 409 and the aluminous earth. A double decomposition takes place during the combustion, the iron is left in the shape of oxide, and the double sulphur-salt of alumina and potash is produced. The burnt ashes being soaked in water, the alum is dissolved ; and the water being evaporated, and the residuum re-dissolved and evaporated several times, the salt is obtained sufficiently pure. It is then allowed to crystal- lize in tubs, and is in a fit state for transportation. The process pursued at Whitby is nearly similar. The shale (sulphate of alumina, containing potash and pyrites) is roasted until the sulphur of the pyrites combines with the alumina and potash, and forms a soluble salt, the iron combining with oxygen, and the other impurities being, for the most part, insoluble. The resulting salt is then made to undergo successive solutions and evaporations, till it is sufficiently pure for the purposes for which it is required. About 1500 tons are annually prepared at Whitby, and the estimated value is upwards of 30,000?. Native alum is sometimes found, but not in sufficient quantities to be worth working for commercial purposes. LIGNITE, OR BROWN-COAL. THE beds of carbonaceous matter that occur in the Secondary or Tertiary formations in England are rarely of sufficient importance to be worth extracting, and the min- ing operations that refer to them possess little comparative interest. There are, however, some localities on the Conti- nent of Europe where these imperfect beds of coal, called lignite, or occasionally Braun-Jcohl (brown coal), offer the only fuel at hand, in districts where wood is expensive, and in these places they have been somewhat extensively worked. 410 LIGNITE. Still even in England, in the south-western part of our island, and before the Welsh and Staffordshire coal was sent into the market, there have been in former times some rather extensive mining operations for this imperfect car- bonaceous matter, although, of course, on a far more li- mited scale than those alluded to in the chapter on coal- mining. The Bovey coal, a tertiary deposit, lying uncon- formably on the beds of the Cretaceous period, in the east of Devonshire ; the Kimmeridge coal, a singular bed, per- haps not entirely of vegetable origin, formerly worked near Kimmeridge, in the clay of that name, on the coast of Dorsetshire; and also the oolitic coal of Brora, already described, have all attracted attention, and have led to the undertaking of many abortive attempts, in order, if possible, to render valuable these imperfect and non-bitu- minous carbonaceous masses, which can never enter into competition with the produce of the numerous and rich coal-fields of Britain. Of all these, the Bovey and the Brora coals are those of greatest importance. The former was worked extensively at the close of the last century ; and, in an account given of it in 1797, it is described as being from four to sixteen feet in thickness, alternating with clay, and obtained from pits about eighty feet deep. At that time it was used in a neighbouring pottery ; and the state of the works appears to be the same at the present day, with the exception of additional excavations that have been made. This lignite emits an offensive smell when burnt, which prevents it from being employed for domestic purposes, except among the lowest cottagers. In some parts of Germany near the Ehine, and in the valley of Switzerland not far from Lausanne, the lignites are both more extensive and more valuable than in our BROWN-COAL. 411 own country. In both these localities, and elsewhere on the Continent, they occur in strata of the Tertiary period and of fresh-water origin, and in the absence of better, or to save more expensive fuel, are used to a considerable extent, though chiefly among the lower classes. The brown coal of Nassau occupies a rather singular position, in many cases immediately overlying a great ta- bular expanse of basalt, which caps strata of the Newer Tertiary period. The coal consists for the most part of the trunks of trees of large size ; it is quite black in the mine, but dries of a brown colour, and it often exhibits distinct marks of woody structure, even allowing portions to be used in shoring up the roof of the mine. It exhibits, however, a gradual transition in different parts of the same mine, occasionally passing into a completely carbonised and even partly bituminous state. The bed is sometimes more than ten feet thick, and is parted by thin seams of clay ; it is worked by a level coming out on the hill side, but there is no reason to believe that it is continu- ous, rather consisting of patches lying at a considerable elevation on the hills. It is horizontally bedded and un- disturbed, but the uneven surface of the basalt on which it rests frequently makes it appear as if it had been dislo- cated subsequently to deposition. QUARRIES, AND OPEN WORKINGS. EXCAVATIONS of whatever kind, although not perhaps immediately dependant on mining principles, possess too much in common with them, and have too great reference to the modes of operation they involve, to be out of place in this chapter. I proceed, accordingly, to describe them, so far as they belong to practical Geology. 412 SLATE-QUARRIES OF GREAT BRITAIN. Slate is a substance so extensively used, and so peculiar in its structure, as to deserve the first place in an account of quarried minerals ; but the nature of slaty cleavage has been already discussed in a former Chapter, and need not detain us now. It is sufficient for my present pur- pose, that the reader should know what is commonly un- derstood by the word slate, and the geological and mine- ralogical characters which distinguish it. The principal slates of the British Islands are found in Cornwall, North Wales, Cumberland, and various parts of Scotland. Of these, the Cornish slates are some of them extremely beautiful and durable, and those of Dela- bole, a well-known locality, combine lightness with con- siderable strength, and have been long celebrated. "Bor- lase, in 1758, states, 'that for its lightness and enduring of weather, it is generally preferred to any slate in Great Britain.' He describes the great quarry as being in his time 300 yards long, 100 wide, and 80 deep ; observing that ' all the slate is carried, and with no small danger, on men's backs, which are guarded from the weight by a kind of leathern apron or cushion.' The mode of working this quarry is, as may readily be supposed, much improved at present ; and the slates in the rough are raised by a whim to the top, whence, after being finally split and shaped, they are carried away by carts and waggons."* Besides this, there are other quarries of good slate near Tintagel, and many in other parts of the district, but not of so good a quality. The slate is in all cases detached from the rock by blasting. Very large and valuable quarries of good slate are worked at Balahulish or Balachelish, in the most northern * De la Beche's Report, &c., p. 503. BALAHULISH SLATE-QUARRIES. 413 part of the county of Argyle, in Scotland, on the side of a mountain rising immediately out of Loch Leven. In these quarries, which have been opened only since the year 1760, the slate is exposed on the mountain side, its cleavage planes making an angle of 80 with the hori- zon ; and, commencing on the shore, the quarries extend southwards along the side of the mountain. The face of the rock is laid open by workings, three in number, fronting the west, and rising one above another in successive step- like terraces, all of them being entered from the north end of the bed ; the height from the lowest terrace to the top of the workings is about 216 feet, and the face of the rock wrought about 536 feet. The first level enters from the high road, 28 feet above high-water mark ; the second is 66 feet above the first, and communicates directly with the sea by an arch thrown over the high road. The third is 74 feet above the level of the second, and is worked to the height of 76 feet, its produce being conveyed down an inclined plane to the level of the second. The Balahulish quarries are very conveniently situated, both the drainage and the waste and broken slate being at once got rid of into the sea. The annual produce some years ago was from five to seven millions of roofing slates, weighing about 10,000 tons; and as in slate quarrying there is at least six times as much broken slate and other solid matter in the condition of rubbish as there is of sale- able produce, the advantage of the position of these quarries is at once manifest. But the quarries at Penrhyn, near Bangor, in North Wales, are beyond comparison the most important both in respect of the extent of the works, and the quantity of slate annually quarried and exported from them. In these vast excavations, which have also the advantage of 414 SLATE-QUARRIES. proximity to the sea, there are no fewer than ten levels, rising one above another to an enormous height, and the slate, when shaped, is carried down at once by a railroad on board the numerous vessels constantly waiting to be loaded. The number of persons employed in these works is upwards of 2000, and the property is said to yield to the proprieters from 30,000?. to 40,000?. per annum. The slates of Cumberland and the lake district, although some of them sufficiently important, are not quarried to any considerable extent for exportation. Near Kirby Ireleth, however, there is an excellent dark-coloured roofing-slate, which has been long worked, and fine beds of dark-colour- ed flagstones have also been obtained from the lower members of the same group. The igneous rocks protruded through the new red sandstone in Cham wood Forest, in Leicestershire, have also brought up some fine roofing- slates, very valuable in that district, and very extensively worked. In all these cases the slates are not more recent than the Middle Palaeozoic period, nor is there any in- stance in England of true slates of a more modern date. In the Alps, however, the causes producing this peculiar mineral structure have affected clays of the Secondary period ; and even of the Cretaceous series, the most modern of all the Secondary rocks. It is, however, rarely that this is the case, and for the most part the slates are con- fined to the old rocks, and seem to indicate an amount of change not producible, except under circumstances ex- tremely different from those which obtain near the earth's surface. Besides the true slates, flagstones of a peculiar kind, and more or less fissile, are frequently met with, and are occa- sionally quarried to supply the place of slate, and they OPEN WORKINGS. 415 sometimes even bear the same name, although they possess none of the peculiar characteristics of that substance. The 6 Stonesfield ' and the ' Colley Weston "* slates are instances of this, the rock in each case being a limestone, which splits readily into thin laminae. Other slabs of fissile stone, called tile-stones, are found in some of the rocks of the Palaeozoic period, and, as well as flagstones, (also fissile beds of sand- stone or limestone,) are occasionally quarried to some ex- tent. Quarries of stone for building purposes will come under consideration in a future Chapter, when speaking of the application of Geology to Architecture, and it is therefore unnecessary now to allude to the subject. It sometimes, though rarely, happens that metallic ores and coal are obtained by the simple process of quarrying, and without extended mining operations. Some of these instances have been already alluded to ; but it may be worth while to mention here, as among the most remark- able, and also as not having been hitherto noticed, the apparently inexhaustible mines of iron in the Isle of Elba, a considerable number of the rich iron mines of Sweden, and, in former times, the well-known copper mines of Fah- lun, also in Sweden. The shape of the vein, its position and the nature of the section exhibited, the changes in its form, and the indica- tions which have caused a greater extent of working in some directions than in others, give very different and sin- gular appearances to the workings which are thus exposed. The Fahlun mines, which are open on the line of intersec- tion of the vein with the surface, offer the appearance of an immense dyke, long and narrow, having a depth of near eighty yards, and the walls being always steep, sometimes vertical, and occasionally overhanging. 416 CHINA-CLAY. The remarkable mine of Rio, in the Isle of Elba, is an- other instance of an open working, situated half way down a steep escarpment which terminates in the sea. The vein has been divided by horizontal terraces into five parts, each from ten to fifteen yards high, and thirty to sixty yards long. The vertical faces of these step-like portions have afterwards been excavated where the richer parts of the vein appeared, and are cut into other steps of more convenient proportions. The successive terraces are con- nected by slopes, which allow the passage of carts and wag- gons to carry away the produce. CHINA-CLAY. AMONG those open workings which come under our con- sideration in the present chapter, I must riot omit to include a singular vein of china-clay worked in Cornwall, and form- ing there an object of considerable commercial importance. This clay is derived from the decomposition of the felspar, which forms a component part of the granite of the dis- trict, but that which is obtained from the vein is by no means the only source of the supply. The greater part of the china-clay exported from Corn- wall is, however, artificially prepared from granite, by washing the decomposed rock in such a manner, that while passing through a series of tanks the heavier and useless particles fall from the water in which they have been held mechanically suspended, but the finer particles, composed of the remains of the decomposed felspar, are carried onwards, and allowed quietly to settle in other tanks. The water being removed from these, and the sediment partially dried, the latter is afterwards con- CHINA-CLAY. 41 7 veyed to proper houses, where the drying is com- pleted. In a district of decomposed granite, such as much of the eastern part of the Austell mass, those places are selected for works of this kind in which the rock contains as little mineral matter as possible, except that formed from the decomposition of the felspar, and where water can be turned on conveniently. The decomposed rock, usually containing much quartz, is exposed on an inclined plane to a fall of a few feet of water which washes it down to a trench, whence it is conducted to the catch-pits. The quartz and other impure particles are in a great measure retained in the first catch-pit, but there is generally a second or even third pit, in which the grosser particles are collected before the water charged with the finer particles of the clay is allowed to come to rest in the larger tanks or ponds. Here the china-clay sediment is allowed to settle, the supernatant water being with- drawn as it becomes clear by means of plug-holes in the side of the tank. By repeating this process, the tanks become sufficiently full of clay to be drained of all water, and the clay is allowed to dry so much as to be cut into cubical or prismatic masses of about nine inches or one foot sides, which are carried to a roofed building through which the air can freely pass, and where the cubical or prismatic lumps are so arranged as to be dried completely for the market. When considered properly dry, the out- sides of the lumps are carefully scraped, and exported to the potteries either in bulk or in casks."""' Sir H. De la Beche adds, that between seven and eight thousand tons of this artificial china-clay are annually exported from Cornwall and Devon. * Report, &c., on Cornwall, Devon, and West Somerset, p. 508. VOL. II. 2 E 418 APPLICATION OF GEOLOGY. I Independently of the artificial china-clay, the district furnishes about 25,000 tons annually of a natural china- clay, formed, it would appear, much in the same manner as is now done artificially, the decomposed granite having been washed down from Dartmoor into a lake or estuary ; so that while the grosser particles were first lodged at its higher end, the fine sediment was accumulated at the lower part. This material is dug from pits excavated through the surface gravel, and being thrown from stage to stage, according to the depth, till it reaches the surface, is then carried to the clay cellars and properly dried. It appears, on the whole, that 37,500 tons of mineral matter (including the china-stone, or unprepared clay,) are annually shipped from the south-west of England to the potteries, and the value of this export must amount to nearly 50,000. A century ago, it does not seem that any part of it was made use of, or that this im- portant produce was then of any value whatever. I have now completed my account of the principal economic uses to which the various materials of the earth's crust have been put, in the cases where those substances required the application of some degree of ingenuity to extract them. It is worth while here to pause a moment, and look back upon this list of mining processes and the application of mining principles, in order to note how far the subjects of the last few chapters have reference to the general nature of Geological science. In the first place, it will be evident that Geology, hav- ing for its object " to observe and describe the structure of the external crust of the globe," every addition that is made to our knowledge of that structure, is a direct gain to Geology ; and that, on the other hand, every ad- APPLICATION OF GEOLOGY. 419 vance made in Geological science, and in arranging and determining the general principles and laws by which the earth has arrived at its present condition, must ultimately tend to the attainment of sound conclusions on the ob- jects before us, and the facts presented to our view in the contemplation of Nature. In other words, as every fresh observation renders our power of correct generalisation greater and more complete, so every generalisation attained, every law discovered, every sound theory founded upon facts and careful observations, is a direct practical benefit. In the next place, I would remind the reader, that as in the Chapters on Descriptive Geology I assumed his acquaintance with the main facts of Geology, now clearly determined, such as the stratification and disturbance of rocks, a fixed order in their superposition, and the like ; so he has in these latter chapters been called upon to exercise the knowledge he has acquired, while at the same time the facts recorded are in every case additional proofs of the general truth of the conclusions. Thus, in the discussions concerning mineral veins, their nature, the circumstances under which they became filled with me- tallic ore, the localities in which they occur, &c.; and in the description of the seams of coal or of iron ore, and the beds of salt, &c., I have made a reference to the general conclusions to which Geologists have arrived, but the additional facts adduced in order to explain the sub- ject all tend in a greater or less degree to bear out those conclusions. And here, again, I may remark, that the relation of Geological science with the most practical of the industrial employments to which I have hitherto had occasion to allude, is strictly mutual, so that the one cannot advance without benefiting the other. The observations of the man 2 E 2 420 APPLICATION OF GEOLOGY. who is merely anxious to advance the interests of his em- ployers, or his own interests, in a mining operation of any kind, are necessarily those which, if he records them pro- perly, are the most useful and valuable in the ultimate determination of disputed points in science. The applica- tion of these observations, on the other hand, and the work- ing them up into general laws, is the method by which the scientific man, who is also practical, repays a hundredfold to his fellow workman, the labour and expense of these records of phenomena. The subjoined vignette (representing a locality on the coast of Ireland) does not bear any special reference to the subjects treated of in this chapter, but it is an interesting example of stratification, exhibited on a grand scale in a sea cliff, and laid bare by the action of the waves. K.1LLEEK DUFF. 421 CHAPTER X. MINING RECORDS. LAWS OF MINING IN GERMANY AND ELSE- WHERE. THE NATURE OF THE RECORDS REQUIRED, AND THE IMPORTANCE OF PRESERVING THEM IN A PUBLIC OFFICE. HOWEVER comparatively unimportant it might seem to the advance of Geology as an abstract science, that there should be a public and secure place for the deposit of documents relating to underground operations, there are, perhaps, few results more likely to be of permanent benefit to the country, and none more certain to establish upon a firm basis systems of observations which may hereafter be the groundwork of extensive and important generalisations, than the preservation of all documents relating to mining, whether conducted in mineral veins, or in beds of coal. Fully impressed with the necessity that there is of bring- ing into one place, and reducing to a system, such docu- ments, and anxious to induce every practical man who may read these pages to assist in this great work, I have determined to devote the present chapter to a considera- tion of the subject, and to point out, so far as I am able, the nature of the mining records which are most necessary, and most likely to be generally useful. It is also greatly to be desired that this subject should at the present moment be put so prominently forth as to attract general attention, because the Government of our 422 ADVANTAGE OF MINING RECORDS. country has exhibited an interest in the matter, by pro- viding a depository for such documents in the " Mining Eecord Office," properly associated with the Museum of Economic Geology, concerning which I have before spoken. The advantage to be derived from bringing together a collection of plans and drawings of the works that have been excavated in mines at any given period, and the de- tails of the workings, must necessarily be very great, both in regulating and giving accurate data for the establish- ment of Geological theory, and also with reference to the phenomena of Descriptive Geology ; while considered with regard to future mining operations, the value of such plans is even greater. Not only will the positions of all old workings be then known, so that they may be avoided, but much direct information will be conveyed as to the prospect that may exist of a successful result in doubtful cases. Perhaps the most effectual method of giving to the English reader an idea of the nature of mining records, will be to preface the recommendations I shall offer on that head, by a short account of the legislative enactments in those parts of Europe where mining has been for a long time so principal an employment, as to have called for special laws, and a separate system of jurisprudence. The mining districts of Saxony, and of the Hartz, are those of greatest interest in this respect. In the Hartz, the general system of laws in common use was established so long ago as in 1593, and is divided into three parts, namely, that which has reference to the officers employed in the mines, that which relates to the mines themselves, the galleries, and methods of working, and that which treats of the methods of reducing the ore. Of these, the first, although not without interest with respect to our own mining customs, is hardly so important as to MINING REGULATIONS OF THE HARTZ. 423 require that any detail should be given here of its enact- ments ; and the third I have already alluded to sufficiently in a former chapter. It is chiefly the second that belongs to the subject of mining records now under con- sideration. In the constitution by which the Hartz mines are governed, there are not less than one hundred and two articles which refer to the manner in which the mines are to be worked, and these are arranged under several heads. The .conduct of the superintendant and other officers, the arrangement of the working hours, the duties payable to Government, the extent of the jurisdiction of the various officers, and many other matters of internal policy, are all amongst the subjects of legislative enact- ment, and concerning many of these, also, but little in- terest would be felt in this country. There are other arrangements, however, of more general importance. The first article in the code is one which gives a condi- tional right of property to the discoverer of a metallic vein, without any interference being allowed on the part of the proprietor of the land on which the vein is dis- covered. The second article provides, that the superintendant of the mines in the district, shall have the power of conced- ing grants, with respect to all kinds of mineral veins what- ever, the person claiming the grant specifying the extent of his discovery, and the exact site. This grant is given for a very trifling fee, and cannot be refused to the first discoverer of a vein. Succeeding articles provide, that within a fortnight of the grant being conceded, the vein must be laid open in such a manner, that the superintendant of the mines can examine it, and that this examination having taken place 424 MINING REGULATIONS OP THE HARTZ. the grant must be confirmed, as it otherwise lapses, and becomes null. If, however, difficulties should arise, ren- dering it expedient to postpone the confirmation of the grant, the superintendant of the mines has it in his power to do so within certain defined limits. The right to the mines being confirmed, the discoverer is obliged to proceed with the work, employing at least four hours each day in working his newly found vein. The ninth article has reference to the important subject of registration, and it requires, in the first place, that all the books and registers of the work done in the mines be safely preserved in a chest, of which the superintendant of the mines, and the secretary of the mining district, have each a key, and these books must always be produced on the application of any person concerned in the workings. The following is a list of the books and registers to be preserved. I. A register of the grants conceded. In this is entered a */ J */ list of all the companies and individuals who have worked the mines, the specifications of the grants conceded by the superintendant of the mines, the extent of the grants, and the nature of the work done. II. A register of the mines in which the work is suspended. In this register an account is preserved of every mine in which the works have been from any cause suspended ; of the reasons for suspending the work, whether from want of water for the water-wheels, &c., or otherwise ; the pros- pects that there are of the work being carried on again ; and the reasons why it should not be considered free, and granted to other adventurers. In this book also are regis- tered the rights of the mine with regard to water-courses, as they have been regulated by the master of the mine and the inspectors.* * The machinery used in most of the German mines was formerly almost en- MINING REGULATIONS OP THE HARTZ. 425 III. An agreement-book, in which all decisions and ar- rangements with respect to disputes or differences that have arisen between adventurers are registered, with a statement of the circumstances attending the difference. IV. A contract-book, in which the accounts of each mine are kept, the expenses of working, the price of the work, the produce of the mine per quarter in silver, lead, copper, See., the debts of the mine, and the quan- tity of ore that has been brought to the surface and not reduced. V. A report-book, in which are preserved the reports of the captain of the mines and the viewers on the actual state of each mine, and the intentions that have been resolved on concerning it. The tenth and three subsequent articles of the code refer to the powers and duties of those who have received a grant of a mine that had been before worked, and direct that the workings shall be carried on under the direction, and with the concurrence, of the superintendant of the mines, and according to a certain plan, a share of the adventure being always reserved for the sovereign. The officers to be employed in the mines, their titles and pay, the powers they shall possess, and the manner of their appointment are next provided for ; and there then follow some curious regulations with regard to the working of new veins or ores found in the progress of the mining operations. These all exhibit very strikingly the right reserved to the crown of claiming the whole of the underground property, and therefore exercising the most complete and absolute direction and control over its management. It is not ne- cessary to dwell on these points, or on the extent of the tirely, and is still to a great extent, worked by water-power. It is for this reason that such careful provision is made with regard to the surface- streams. 426 MINING REGULATIONS IN ENGLAND. concession made to an individual or company, and the powers they possess of extending their works. Most of the remaining articles have reference to the mag- nitude and extent of the galleries and shafts, and the cir- cumstances under which they may be carried on and en- larged by the adventurers. However limited the power of the adventurer may seem to be under these regulations, the case was not very dif- ferent in our own country with respect to the mines of Cornwall, which have been the subjects of special legislation, first in the year 1201, when a charter was granted by King John, and afterwards in the beginning of the next century, under Edward the First. It was not, however, till the reign of James the First that a regular code was esta- blished, and the mining regulations actually made binding. At that time, unfortunately, no mining records were in- sisted on, and no attempt was made to register the accounts of the different mines, so that in this respect England has been greatly behind her continental rivals. The mining district of Derbyshire was formerly a royal domain, and was governed by a code of laws, some of which were sufficiently arbitrary and singular ; but here also no mention is made of preserving the plans and other records of the different mines, which have accordingly been worked with great irregularity, and often with little regard to real and proper economy. The code of laws by which the working of the mines of Saxony is governed, resembles that already described as regulating the Hartz district, in many of its more impor- tant provisions. The Bergmeister, or superintendant of the mines, is a public officer appointed by Government to con- trol all the mines of the district, and it is his duty to grant concessions such as those given in the Hartz. Every prac- MINING REGULATIONS IN SAXONY. 427 tical facility is given to encourage a steady working of the mines, and every effort made to have them worked to the greatest advantage. The records preserved are, on the whole, almost as extensive as is needed, and are always to be referred to by those interested in the workings ; and there is one point especially attended to, which in our own country has been most shamefully neglected, I mean the preserving a great formality in closing a mine, and handing down a minute account of the condition of the mine when it ceased to be worked. The following are the directions with reference to this point : When a mine is to be abandoned, the superintendant of the mines and the inspectors (officers appointed to inspect the mines from time to time in succession, throughout the district, and report on their condition) visit the works, detach portions of the ore, if any is to be obtained, assay it, note its condition and value, and mark down these observations on a ticket which they attach to the specimen, and which it is their duty carefully to preserve. They register in a book, kept for the purpose, all the circumstances which have led to the abandonment of the mine, mentioning the magnitude of the vein, the hardness of the rock, the proportion of ore it contains, the depth of the workings, the nature, direction, and magnitude of the galleries, and the distance to which each has been carried. It is not allowed that the persons abandon- ing the mine carry away that part of the machinery and ap- paratus attached by nails and iron clamps, nor may they re- move the rubbish, nor even the ore that has not been washed, the refuse from the washings and siftings, and the unpicked ore. Even if these things have been sold, the sale, being ille- gal, is declared void, and only such matters can be removed as have been purchased by the adventurers themselves, for instance, tools, and ore that has been fairly extracted. 428 MINING RECORDS. If some of these provisions might seem incompatible with English habits, and the rights of property as they exist amongst us, the principle at least might be obligatory; and no proprietor should be allowed to leave underground works in an imperfect, unfinished, or dangerous state, or without such distinct indications of the actual condition of the works as may guard those who may succeed them from the fearful accidents that have occasionally resulted from coming suddenly and unexpectedly upon extensive and ne- glected workings. To see that such notice is given as may serve to warn the future proprietor of an imminent danger, is surely a duty incumbent on Government, and one which loudly calls for legislative enactment in England. With regard to mining records generally, perhaps the following are those most important to be attended to, and copies of them should be preserved in some public place, with respect to every mineral vein worked in the country. I. Accurate underground plans of the works on each level, and vertical sections through every vein and cross- course worked in the mine. To these plans should be at- tached notes referring to every fault and slip met with, its amount, direction, and effect on the vein, and the changes occurring from time to time in the vein, on passing into new ground, or traversing a dyke. II. With regard to the veins themselves. A. The exterior relations of the vein. 1. Its position, viz. : its distance from known points, its direction, and its inclination. 2. Its magnitude, viz. : its length and width at various points, the manner in which it termi- nates, and the way in which it ramifies. B. The internal state of the veins. 1 . The predominating ores and veinstones, and the MINING RECORDS. 429 order in which they are found in relation to one another. 2. The other ores and veinstones, and the circum- stances under which they also occur, their fre- quency, size, richness, and the places where they are found. 3. The remaining internal circumstances of the vein ; the fragments of rock found mixed with the substance of the vein ; the mechanical con- dition of the filling up of the vein ; the walls which separate it from the adjacent rock ; and the nature of its adherence to the rock. c. With regard to the adjacent rock. 1. Its nature and its Geological relations with the vein. 2. The inclination of the strata, if the rock is stra- tified, and the predominating joints and divi- sional planes. 3. The condition of the rock near the vein, and the greater or less amount of decomposition it has suffered ; a statement of the metallic particles with which it is impregnated, and the fractures it has undergone. 4. The effect of the surrounding rock upon the vein, as well as that of the vein upon it. D. The relation of the vein under consideration with ike other veins which it meets, and reciprocally. 1. The direction and inclination of the veins at the point of meeting, the nature of the ores and veinstones, and the change, if any, that takes place at the intersection. 2. The peculiarities presented by smaller veins, or 430 MINING RECORDS. threads, at their intersection with the principal vein, observing the following points : a. If, after meeting, they continue together for some time. I. If the veins that meet the principal vein also cross it ; or, c. If they are crossed by it. d. If they produce ramifications, break the vein, or are broken by it ; disturb it, or have been dis- turbed by it ; and the magnitude of all these effects, if they have been produced. e. If they intercept and stop the course of the principal vein, or change it into mere threads, or are themselves intercepted by, and swal- lowed up in it. E. The principal works done in the vein. Under this head should be noticed the excavations, and other trial works made in new ground, whether successful or not, in finding ore, as well as all details connected with the regular workings. An account should also be given of the extent of each mining property, and the name of the proprietor. The above intimation of the kind of information required concerning mineral veins is chiefly taken from Werner's " New Theory of the Formation of Veins," a translation of which into English was published at Edinburgh in 1809. I cannot conclude this part of the subject more appropri- ately than in the words of the great Saxon Geologist. He says, " Such an account of mineral repositories requires much trouble, and a considerable time, to render it com- plete ; but, from the very commencement, every step made in the labour will be profitable and useful of itself; while it is only by adding, from time to time, the new observations MINING RECORDS OF COAL-MINES. 431 arising from our labour that we can hope to render it per- fect. Such a description of a mining district would indeed form together a complete and instructive whole. If our ancestors had left us such documents for two centuries past, or even for half a century, of what advantage would it not have been to us ? From what doubts would it not have relieved us ? With what anxiety do we not turn over the leaves of ancient chronicles in search of information, often very imperfect, obscure, and uncertain ? With what pleasure do we not receive the least sketch or plan of some ancient mine ? With what pains do we not rake up the heaps of rubbish brought out of old excavations, to discover pieces which may afford us some idea of the substances which were formerly worked out ? Yet between these documents and those which we might obtain in the way pointed out in the preceding paragraphs, there is as much difference as between night and day. Ought it not to be an obligation and a duty, for us to collect and leave to future generations as much instruction and knowledge as possible on the labours carried on in our mines, whether it be in those that are still worked, or in those which have been given up."* But it is no less necessary that mining records should be preserved of those districts worked for coal and other mineral produce obtained from seams and beds, than that an account should be kept of mineral veins. I may quote the authority of the late Mr. Buddie, with reference to this subject, and in testimony that " the inconvenience and unnecessary expense which have frequently been occasioned in the Newcastle and other coal-fields, as well as the many fatal accidents which have happened from the want * Werner's " New Theory of the Formation of Veins," translated by Dr. An. derson, p. 205. 432 MINING RECOKDS OF COAL-MINES. of accurate plans and records of the former workings of exhausted or relinquished collieries, have long been a sub- ject of public regret, as well as of individual loss and suf- fering."* It is greatly to be desired that this neglect in preserv- ing documents, and in accurately recording the condition and extent of the workings in every mine, should be re- medied ; and even so long ago as the close of the last century, an attempt was made, which was again repeated in 1815, but on both occasions the endeavours to excite due attention proved abortive, partly, it would appear, from there being no suitable place in which to collect and deposit the requisite information and documents for effect- ing this desirable object. Mr. Buddie, in the paper above quoted, (dated 1834,) " has proposed to set apart a division of the Museum of the Northumberland Natural History Society, for preserving these records, and the advantage of their being retained on the spot for future reference is too evident and consi- derable to allow any one to question the reasonableness of this plan. It might, perhaps, be advisable, that in every district there should be some such local record office, but, at the same time, copies of all the documents might be forwarded to the Mining Record Office in London, where a proper official person would have the charge of them, and where they would be preserved with that care which their importance demands. The nature of the records, and the information which it is suggested by Mr. Buddie they might include, may be arranged under the following heads.*}" * Transactions of the Natural History Society of Northumberland, vol. ii. p. 309. f Transactions, &c. ante cit. p. 310. NATURE OP THE RECORDS. 433 1. The name of the proprietor of the surface and minerals. 2. The locality and extent of the property. 3. The number and description of the seams of coal and other minerals which it contains. 4. The thickness and quality of the several seams of coal ; which of them have been worked ; to what extent they have been worked ; and why the working of any of them has been discontinued, or not commenced. 5. The winning of the colliery, viz.: The number and position of the shafts ; the difficulties met with in sinking, and the method of overcoming those difficulties. 6. The system of working ; whether by pillars, by the long method, by pannel work, or in what other way. 7. The dip and rise of the colliery. Description of the dykes, &c. 8. An account of the accidents that have happened by explosion. 9. The other accidents that have happened in the col- liery, with their causes. 10. The system of ventilation practised. 11. General observations. To these may be added, in those districts where the ores of iron are bedded with the coal, an account (1) of the number, thickness, position, and extent of the seams of iron ore ; (2) their relative value, and the per centage of metal obtained from them ; and (3), The manner in which they have been worked, whether subordinately to the coal, or as a principal mineral product. Besides this, very particular attention should be paid to the preservation of accurate j>lans of discontinued workings, with such refer- ences as may render it impossible to mistake the localities to which these plans refer. This latter is the more necessary, VOL. n. 2 F 434 MINING RECORDS. since up to the present time, and even in cases where reports of the state of the underground workings have been preserved, they have often been found useless, owing to the impossibility of identifying the pits. This inconvenience was very strikingly exhibited in the drowning of the Het- ton colliery in 1815, the water breaking in from workings which had not been relinquished more than seventy years. It should be very carefully noted in the description of relinquished workings, whether the pits are filled up, or only scaffolded ; and if the latter, at what depth. The compass bearings of all the workings should also be laid down, and the amount of magnetic variation recorded, that at any future time the accurate position of the under- ground excavations might be understood and ascertained at once from the plan. It should also be remembered, that those who are de- sirous of assisting in this important work, " should not be deterred from giving very full and detailed accounts from the apprehension of being considered too prolix and tedious, as on such a subject it is more excusable to say too much than too little."* I am unwilling to conclude this Chapter, without once more endeavouring to impress upon the reader the very great importance of the subject, with respect to the future progress of mining in this country. The more extensive our mining operations are, and the more they surpass those of other nations, so much the more necessary is it that such a knowledge of them should be preserved and handed down, as may guide those who succeed us to the most probable localities for obtaining what remains of our mineral trea- sures. Nor is such a knowledge less important as a warn- * Mr. Buddie's paper in the Transactions of the Northumberland Natural History Society, ante (At. p. 336. MINING RECORDS. 435 ing to turn away the fearful risk of coming unexpectedly upon some neglected and forgotten excavation, whence may issue a torrent of water, inundating the works, and drown- ing those employed in them ; or a rush of foul and explo- sive gas, yet more destructive, if possible, to life and pro- perty, and yet more instantaneous and resistless in its course. There can be no real excuse for the neglect of which such accidents are the terrible result, and it is a duty imperative on every one to do all in his power to re- move the disgrace, and the extreme inhumanity, of that carelessness in the management of mining property in Eng- land, from which these accidents necessarily follow. The vignette represents an ingenious contrivance for shipping coal at once from the waggons in which it is brought to the pit mouth. These waggons are conveyed by a tram-road to the port, and descend by their own weight into the vessel, where they discharge their load, the empty waggon being lifted to the tram again by a counterpoise. DROPS, AT SUNDERLAND. 436 CHAPTER XL ON THE APPLICATION OF GEOLOGY TO ENGINEERING AND ARCHI- TECTURE. ROAD AND CANAL MAKING : THE CONSTRUCTION OF HARBOURS, BREAKWATERS, QUAYS, AND BRIDGES. RAIL- WAY SECTIONS. IF it is desirable that those persons who are employed in mines and other excavations beneath the earth's surface, should be acquainted with the facts and conclusions arrived at by the study of Geology, it is no less important that the Engineer and the Architect should possess information of the same kind, for upon them devolves the management of great public works, and the construction of buildings, which should in all cases be as durable and as perfect as possible. The different heads under which we may consider the application of Geology to Engineering and Architecture are the following: (1) The making of roads and canals, under which head is included tunnelling and embankments ; (2) The construction of harbours, breakwaters, quays, and bridges ; (3) The selection of sites for public buildings ; and (4), The selection of building materials. Each of these subjects is well worthy of separate and detailed consideration, and each of them has immediate reference to Geology, in the strictest sense. I. ROAD-MAKING AND CANALS. With regard to this subject there are two points in which the application of Geology is both immediate and ROAD-MAKING AND CANALS. 437 evident. These are (]), The selection of the line along which the road or canal is to be carried, and the manage- ment of the cuttings and embankments that may be deter- mined on ; and (2), The selection of the materials for their construction. I can only point out the nature of the application under the most obvious circumstances, and shall do so as briefly as possible in every case. 1. The selection of the line for a road or canal, and the management of the cuttings and embankments. Although the selection of a line, whether for a railroad, a common road, or a canal, is a matter that must be in- fluenced by many considerations, which may render it ne- cessary to depart from that direction suggested by the structure of the country and possessing the most obvious physical advantages, it is certain, that as to make use of these should always be a great object, and as it is the duty of the Engineer to mark out the line most truly economical and the best under all the circumstances, it is not a little necessary that he should know beforehand some- thing of the Geological structure of the district he is about to decide on. In the case of a railroad, more than ordinary care and attention is often required to enable the engineer to de- cide how far he may safely, and with justice to his em- ployers, contemplate the overcoming of natural difficulties in a country to be passed over, in order to escape from other difficulties of a different kind, arising from the local value of property, and the arrangements that have to be made with landowners. In this respect, an acquaintance with the principles of Geology cannot fail to be exceedingly useful, as suggesting resources, the existence of which could not otherwise be guessed at, or, at least, which could 438 APPLICATION OF GEOLOGY TO ENGINEERING. not be discovered without a minute local knowledge of the district. For, let us suppose two engineers, the one unacquainted with the order of superposition of the strata, and ignorant even of the fact of stratification at all, in its Geological sense, and the other a practical and well-informed student of Geology. And let us assume these two men to be required to construct a line of railroad from London to Dover. The mere engineer, having no knowledge of Geology, would only be aware, in a general way, that between London and the Weald of Kent, there was a range of chalk hills, (the North Downs,) but that afterwards the country was toler- bly level, as far to the east as Folkstone. He would soon find that, with the exception of the Dart and the Mole, two rivers running into the Thames, the one at Dartford in Kent, and the other near Kingston in Surrey, there was no complete drainage across the hills, and therefore no con- tinuous valley leading to the level country, and these two valleys would both be found ill adapted for the object in view. On further examination, partial valleys would, how- ever, be discovered, and one of these, we may suppose, would be selected as the most convenient. The rest of the work to Folkstone would be calculated for as work of the ordinary kind, and cuttings and embankments would be made without any reference to the peculiar circumstances of the strata. Let us now see what would be the inquiries and conclu- sions of the Geological engineer under similar circum- stances. The line of road by Croydon is sufficiently mark- ed out by the physical geography of the district, and need not be again referred to. Our engineer, however, having settled these preliminaries, would consider that in the course of his work he must cut through a considerable ROAD-MAKING. 439 portion of the lower part of the London Clay, which he would know beforehand to consist of sand and gravelly matter, mixed with some tenacious clay, and that he would then have to tunnel through the chalk, coming out upon the lower beds, which on examination he would find were con- siderably tilted towards the north. His line would thus carry him along the direction of a small disturbance trans- verse to that which had originally elevated the beds of chalk. Through part of this he would have to tunnel, and he would be aware that in a district like that extending along the line of the chalk hills there was little danger of meeting with hard beds, or with intruded igneous rock. The advantage of being thus able to predicate with con- siderable certainty as to the nature of the ground through which the road was to be cut, must be evident to every practical man, and we shall soon perceive how far such knowledge is immediately applicable. Besides this ac- quaintance with the condition of the chalk the Geologi- cal engineer in this case would remember that his cuttings and embankments would have to be made for the most part at right angles to the strike of the beds, but that in some cases the London Clay, having a different local dip, would be cut in a slant direction. Lastly, he would be aware that when he had crossed the chalk, and the other beds of the cretaceous group, he would come upon the Weald Clay, a bed dipping northwards, and which he would have to traverse in a westerly direction, and there- fore directly on the line of strike. Now the beds of the London basin, consisting, as they generally do, of clay alternating with occasional sands, are exceedingly dangerous when deep cuttings or tunnels are made through them, which are not properly defended. And this is the case, because the rain, washing through 440 APPLICATION OF GEOLOGY TO ENGINEERING. and carrying away the sands where a section has been made, leaves the upper bed of clay barely balanced upon the lower, and with a slippery surface between them. The inevitable consequence of such a condition of things is, that after a short time the upper bed slips quietly down in the direction of its dip, falling upon and filling up the cutting that had been made through it. Accidents of this kind have happened too frequently not to be familiar to every engineer, and the cause is now to a certain extent generally understood ; but nothing short of a knowledge of the structure of the country, or, in other words, of the principles of Geology, will enable any one effectually to avoid this danger, because it is one constantly recurring, and requiring different management, to a certain extent, for each individual case. The Geological engineer will know his danger, and will endeavour to provide against it beforehand. The mere empiricist who knows only the rule of practice on the occasion, will, perhaps, bring out at last the same, or nearly the same, result ; but it will be by that most expensive and least creditable of all methods, a succession of failures.* The remarks that are so especially applicable to the London Clay, and the truth of which has been too fre- quently, and too practically illustrated, to be questioned by any one, also apply in a degree to all clayey beds, and amongst the rest to the Weald Clay. In the case of the * It would be interesting and exceedingly instructive to consider, with respect to their bearing upon Geology, several of the great lines of rail-road in England and elsewhere. It would be found that all of them, without exception, have reference at least as much to the Geological as to the Geographical structure of the country, and that in each, the great works in cutting^and tunnelling, if they were not originally constructed on those principles advocated in the text, have been since altered, or must shortly be altered, in consequence, or in certain anticipation, of accidents* But in the outline of the subject at present offered, such a detail would be clearly out of place. ROAD-MAKING. 441 Sonth-Eastern Railway, the Weald Clay is, on the whole, the most difficult to engineer with safety, because the cuttings, although not numerous, are nearly on the line of strike, which is the most unfavourable of all conditions, the smallest amount of resistance being offered by any natural or artificial defences in case of a tendency to slide. The only defences, indeed, in these cases seem to be, (1) Thorough surface drainage on the line of outcrop of each bed cut through ; (2) A greater slope on the rise side of the bed than fs necessary on the other or dip side ; and (3), Careful attention from time to time to see that no tendency to a slip shows itself.* The methods to be pursued with regard to clay cuttings, and the accidents that are incidental to them, belong as much to cuttings for ordinary roads and canals as rail- roads, and are applicable in many cases, when other beds than clay (such as courses of limestone) are separated by partings, which on exposure to the atmosphere, or on suffering the drainage of water through them, become slip- pery, and cause the upper and lower beds to lose their co- herence. Even in an embankment, if the successive layers of earth are not level, an accident not unfrequently happens from the same cause, the moisture penetrating the beds, and if not loosening them under ordinary circumstances of tem- perature, affecting them afterwards during severe frost, when the expansion of the freezing water produces effects that can hardly be calculated, until they are unhappily seen and felt. The advantage derived from a knowledge of Geology in engineering consists (it will now be understood) in * Watson's patent method of draining, by pipes inserted into the clay to a considerable distance, and ironstone -clay pipes, made with undercut apertures, are important defences in some cases. I shall allude to them again in the chapter on Drainage. 442 APPLICATION OF GEOLOGY TO ENGINEERING. teaching the engineer how to avoid danger, or if he must be exposed to it, how to provide a remedy from the be- ginning. It often happens that a tendency once produced in the beds to slip, cannot afterwards be stopped, although the first step towards the mischief might have been pre- vented by timely application of preventive measures. The loose kind of sandy earth, sometimes forming into a conglomerate, and sometimes passing almost into marl which is often found in the lower part of the London Clay formation, and also in the New red Sandstone, and in some parts of the Greensand series, requires not a little patient management to allow of a cutting being safely carried through it, but in attempting this the Geological engineer will have a considerable advantage over his rival, ignorant of the nature of this science. The slope, in such dangerous cuttings, should have some, and often a considerable reference to the dip of the bed, for however it may seem that the rain and other atmospheric agents must wash away the loose sand equally on both sides of the road, this is by no means the case in reality, and the washing will be far more rapid, and the tendency to slip down in large masses incomparably greater on the one side than on the other. The reason of this will be seen at once by a glance at the annexed diagram, for on the one side each particle that faces the slope is supported by the one behind it, but on the other it is pushed on and forced forwards by its weight. IDEAL SECTION ACROSS A RAILWAY CUTTING. On the one side, therefore, of such a cutting the judicious planting of grass will often be a 'sufficient defence even TUNNELLING. 443 with a steep slope, while on the other, even a stout wall will be insufficient to prevent a slip from the very first day of exposure.* There are, indeed, very few cases in which the considerations of geological structure and relative exposure ought not so to modify the calcula- tions of the engineer as to induce him to make a greater slope on one side than on the other of every deep cutting. The circumstances under which tunnelling is advisable are also greatly influenced by the Geological structure of the district under consideration, and the direction along which a road or canal is to be carried must, in some cases, depend on the probability, or otherwise, of tunnels in certain directions being practicable. Hills of a particular shape, and under certain circumstances, will be suspected by the Geological engineer of having a nucleus of igneous rock, and will therefore be avoided, but in this case, as the external coating of the hill may be of moderately soft material, there is no other than a Geological indication of a condition which might greatly interfere with the completion of a contract, and check the progress of an important national undertaking. The nature of the beds, the condition of the stratification, and the number and extent of the faults in the vicinity are also matters that claim the most serious attention of the engineer, and ought to become the subject of careful consideration before any conclusion is arrived at, or any calculation made ; for these cannot but influence very considerably the rate of progress and the cost of execution of any work that * The direction and the degree of exposure of the face of the cutting in such cases will also be important subjects of consideration. In our own country a south-west exposure is in most cases far more likely to be affected by atmospheric causes than any other ; but this is not invariably the case, and may by local in- fluences be less liable to be injured than any other. 444 APPLICATION OF GEOLOGY TO ENGINEERING. may be undertaken.* In short, in every operation of surface or deep draining, of cutting, tunnelling, and even of embanking, there should be constant reference to the Geological structure of the country and district ; and, therefore, a practical knowledge of the elements of Geo- logy is required by the engineer in every important em- ployment concerning road or canal-making in which he may be engaged.-f- 2. The materials for the construction of roads, $c. Nor is a knowledge of Geological facts and conclusions less necessary in the selection of materials than in the original laying down the line of a road. This matter, indeed, simple as it may seem, is one that has been so rarely put before the public in a proper form,, and has received so little attention, that it will perhaps by many persons be considered unworthy of notice as one of the important applications of Geological science. But the fact is not so, for not only does a great deal depend on the * In making a road, lines of springs are sometimes cut into, which may prove injurious to the road, and occasionally a hard supporting stratum may be cut away, and the road thrown upon a clayey or loose sandy foundation, requiring great but unnecessary expense in forming a hard artificial bottom. Both these accidents will be avoided or provided against if the engineer has any sufficient knowledge of Geology. f- " In projecting lines of canal, particularly where tunnels are to be constructed, a knowledge of the geological structure of the country is not less necessary than in the case of roads. The probability of meeting with springs of water, the porous or impervious character, as regards water, of the rocks to be traversed, and the kinds of rock which will be encountered in cutting, may all in a great degree be foreseen by those who have examined the geological structure of the district. Hence good geological maps will be found of great value to those who are about to form canals. They also point out the various mineral substances which may advantageously be brought to the canal for the purposes of traffic. From a know- ledge of this kind, canals have been made to pass by or through tracts of country where limestones, coal, or metals are discovered." De la Beche's 'How to Ob- serve. Geology," p. 302. MATERIALS OF ROADS. 445 original soundness of the foundation, but there cannot be a doubt that when the foundation is once laid, the material that is to form the surface should be most carefully se- lected, with a view to its durability under all circum- stances of atmospheric change, as well as with reference to the passage of heavy weights over it. It may be considered that the following is the order in which different kinds of stone may be arranged with respect to their qualities as road material ; the first-men- tioned being those least advisable. Soft decomposable sandstone, soft limestone, limestone, hard sandstone, flint, chert, compact granitic rock, basalt, and undecomposable trappean rocks.* Eoadstones, it will be remembered, have to resist not only friction but pressure, and they require, therefore, to be both hard and tough. For this reason, chert, though not harder, being tougher than flint, is a far better road material, and the more brittle granitic rocks are usually inferior to basalt, greenstone, and other contents of dykes often abundant in particular localities. It will be evident therefore that the selection of the pro- per materials for road-making is best made by the person who adds a knowledge of Geology to his professional education. Such a person will at once know, by refer- ring to a Geological map, where he can obtain that kind * " Flint makes an excellent road if due attention be paid to the size ; but from want of that attention, many of the flint roads are rough, loose, and expen- sive. " Limestone, when properly prepared and applied, makes a smooth, solid road, and becomes consolidated sooner than any other material ; but from its nature it is not the most lasting. " Whinstone is the most durable of all materials ; and wherever it is well and judiciously applied, the roads are comparatively good and cheap. " The pebbles of Shropshire and Staffordshire are of a hard substance, and only require a prudent application to be made good road materials." M'Adam's Re- marks on the present system of Road-making. 8vo. London, 1823. Page 10. 446 APPLICATION OF GEOLOGY TO ENGINEERING. of material which under all circumstances will he the most economical. He will be able to take advantage of any change in the rocks at the surface, and will judge of the probability of obtaining by proper search some vein or dyke filled with igneous rock that may more than repay the expense incurred in discovering and working it ; he will, at any rate, select the material which he has reason to believe will ultimately prove the most economical, and he will open quarries for this purpose with some degree of certainty, convinced that he is making a reasonable selec- tion, not a chance speculation. II. HARBOURS, BREAKWATERS, QUAYS, AND BRIDGES. The construction of such public works as harbours, quays, bridges, &c., requires a familiar acquaintance with the structure of those portions of the earth's crust which do not appear at the surface, and would seem therefore to call for some degree of Geological knowledge in the engineer who undertakes them. In those cases in which the attacks of the sea are to be resisted and repelled by human contrivances, it must manifestly be an all-important object rather to make nature fight against herself, if one may so say, than oppose the feeble barriers of man's invention to the never-ceasing action of winds and waves ; and it is only, in fact, when circumstances are thus taken advantage of, and one series of natural operations is made to repel another, that any ultimate success can be attained. The discovery of the means in these cases must be greatly assisted by an ac- quaintance with the structure of the earth's crust beneath the surface. HARBOURS, BREAKWATERS, ETC. 447 In the case of some of these works the determination of the site is a point in which a knowledge of Geology may be useful, but this knowledge may also be applied to advantage in selecting the material to be used. It may often be observed, that the sea, although encroach- ing manifestly on an extensive line of coast, is apparently retiring in some particular spots on this same line. In- stances in which the very consequence of that tearing and grinding away of the coast on an exposed headland serves to defend and even reclaim land in an adjoining bay, are valuable lessons to the engineer, and teach him how to arrange his forces in the contest he is about to wage with Nature, and where to place his greatest resisting power so as to produce the most effectual and most lasting shelter. With regard to the materials to be employed it may be observed, that they are valuable almost in proportion to their specific gravity when they are to be exposed to the beating of the waves beneath the surface of the water, but that when exposed to the alternate action of air and water, they require qualities of a different kind, and must be selected accordingly. Sir H. De la Beche has remarked, that "an observer may often obtain information on this head by studying the condition of the rocks on the banks of rivers, and on the sea-shore ; and Geologists are thus frequently aware of many situations where quarries for the purposes above mentioned may be advantageously opened." * I ought not to conclude this chapter without calling the attention of those who may be willing to avail themselves of opportunities that are afforded them, to the advantage that may be anticipated from the careful construction of * ' How to Observe. Geology." Page 311. 448 APPLICATION OP GEOLOGY TO ENGINEERING. Geological sections of railway cuttings and tunnellings. The formation and preservation of these profiles of the railways of the United Kingdom, was first suggested by the Geological Section of the British Association in 1840, and a grant was made in accordance with this sugges- tion, chiefly with a view of putting on record (before the slopes of the excavations became soiled over, and covered with vegetation,) the Geological appearances and strata developed by the various openings made through the country in the operations of modern engineering. A large number of Geological railway sections procured by means of the active co-operation of all the officers of railway companies applied to, have been now collected at the expense of the British Association, and have been de- posited in the Museum of Economic Geology ; and it is understood that similar sections will be procured of future lines of railway by the authority, and at the cost of Go- vernment. It has been well observed, with reference to these sections, that " to the practical engineer they offer a memorial of the experience of his profession, whence many a serviceable lesson for future operations may be learned, whereby difficulties and expense may be hereafter avoided and diminished, and from which valuable information may 'be derived for the appliance of materials in constructions, (it being one of the greatest arts of the engineer to avail himself of the most immediate natural resources, which he has to displace in one instance, and to apply them usefully in another when in juxtaposition). On the other hand, the minute variations of the strata and soil thus accurately delineated, and referred to well-defined alti- tudes above the general level of the sea, become of the very highest interest to the Geologist, and no less so to the mining engineer." RAILWAY SECTIONS. 449 A large number of such sections have been finished, (as many as 151 sheets,) and sections have been prepared also for 167 miles of railroad, while numerous documents accompany them, containing, in many cases, full details of those strata that possess any extraordinary interest. The records being deposited in the Museum of Economic Geology are now open to the public, as are the other documents in the Mining Record Office, on proper applica- tion being made to the keeper.'' 5 " * The following is a list of the different railways of which the finished sections are prepared. Glasgow, Paisley, and Greenock ; Manchester and Leeds, Hull and Selby ; Manchester, Bolton, and Preston ; Bristol to Bath ; in all 151 sheets. Besides these, a list of blank sections of the following railways has been pre- pared for Geological colouring. North Midland, Midland Counties, and North Union ; Manchester and Sheffield, Manchester and Birmingham, and Manchester and Liverpool ; in all 167 miles of railroad. CARLINGFORD CASTLE. VOL. II. 2 G 450 CHAPTER XII. THE APPLICATION OF GEOLOGY TO ARCHITECTURE. BUILDING SITES AND BUILDING MATERIALS. LIMESTONES. IN Architecture, as in all kinds of engineering works, the benefit derived from a knowledge of Geological science is shewn, not only with respect to the foundation of the building, but also in the selection of its site and the materials of which the superstructure is composed. In the case at present before us this benefit is chiefly obtained in the selection of building materials, but it also has re- ference to the other part of the subject, for there can be no doubt that the foundations of all buildings, more especially of those which are intended to last for centuries, should be most carefully selected, so as to possess the advantage of thorough drainage and be unaffected by any changes that may take place on the surface by the action of ordinary atmospheric causes. It is true that of late years contrivances have been discovered by which much of the injury resulting from damp may be avoided by making use of compositions which form an artificial and water-tight base for the build- ing ; but it can hardly be too much to say, that a pru- dent architect would rather be dependant on natural con- ditions than on artificial contrivances for a subject of such great importance, and that, therefore, in every case, the APPLICATION OF GEOLOGY TO ARCHITECTURE. 451 selection of a well-drained site is an object worthy of the most careful consideration.* It will appear from what is said in the chapter on draining, to which I must here refer the reader, that the selection of a well and naturally-drained site, and a know- ledge of the means by which thorough drainage can be accomplished, are only to be attained by combining an acquaintance with the principles of Geology with pro- fessional knowledge. It may often happen that a building is to be erected on the side of a hill, or by a river. In this case, if the dip of the strata is towards the slope of the hill, as in the above diagram, there may be some danger lest, after particularly unfavourable seasons, the beds should slide upon one an- other, and tend to fall into the valley. There can evidently be no stability in a building so situated, although the cause is only apparent when we look to the Geological structure of the district. But it is chiefly in the selection of building materials * No dependance can ever be placed on a building of which the foundations are not laid on thoroughly drained ground ; but a very ingenious method has been lately adopted of avoiding the evils of a slippery clay foundation by cutting a large trench below the substructure of a building and filling it in with sand well rammed. It is found that when courses of stone are laid on such a basis no settlement takes place, and it appears that this method has been successfully practised in some of the ancient buildings of Egypt. 452 SELECTION OF BUILDING MATERIALS. that Geology is of importance to the Architect, and is so necessary an element in his professional education. With regard to this subject there are two cases to be considered ; first, that in which the building is to be constructed with as great a regard to economy as is consis- tent with moderate durability, while in the second, the object being to construct an edifice that may be as per- manent as possible, the best economy is to provide that material which is the most likely to be lasting at whatever expense of time and labour. In the first case, we have to consider what kind of stone or other material that is found in the neighbourhood is the best under all the circum- stances.* In the second it will be necessary to extend our inquiries further, and learn which of all the materials avail- able in the country is the most durable, and the best and most truly economical under those conditions of exposure which the building is likely to suffer. The first, therefore, has reference to domestic architecture under ordinary cir- cumstances ; the second to such public buildings as are from time to time undertaken, and which, when com- pleted, serve as the monuments of a nation's power and wealth, and an index of the degree of advance made in the arts at the time of their erection. With regard to house architecture of the ordinary kind, the material selected for building must necessarily be both cheap and ready at hand ; and the position of many large * I have been told by a practical man, who had been employed in selecting stone for an important public building about to be erected, that in looking out for good stone, he was accustomed to go to the churchyard in the neighbourhood of the quarries he wished to judge of, and examine on all sides the oldest tombstones that were there. He found that he could determine by that means the relative value and durability of most of the stones in the neighbourhood, because they were there exposed under almost all conceivable circumstances. A laminated stone, however, that might be extremely decomposable as a tombstone, would not necessarily be bad in the wall of a building, where its edges only are exposed. BUILDING MATERIALS. 453 cities in the vicinity of tough clay has been the cause why for all common purposes brick has been made use of instead of stone. The neighbourhood of good building material might, however, be one object of consideration in selecting the site of new cities in the colonies and elsewhere, although this of course must yield to other points of convenience or advantage.* Dismissing, however, the consideration of private dwell- ings, there are, it may be fairly asserted, scarcely any kinds of public works erected in which the selection of a building material ought not to be a very important consideration. A stone which resists exposure to the air may be readily disintegrated by water, and on the other hand, a porous sandy rock will resist the action of water, but fall to pieces when exposed to frost and atmospheric changes. Many kinds of stone are sufficiently durable for sheltered situa- tions, but crumble away when more exposed ; others are durable in the country, becoming covered with lichens, which preserve them from atmospheric action, but are dis- integrated in towns where the covering of soot they soon * Sir Henry De la Beche observes with reference to this subject : " The rela- tive facility with which good materials may be obtained in a district is, to a cer- tain extent, marked by the appearance of the towns and villages in it, the compa- rative cost of obtaining them being in general better shewn by the character of the ordinary houses than by that of the public buildings and larger mansions, the stone for which may sometimes have been carried comparatively considerable dis- tances. From the frequent practice, however, of selecting those stones which yield readily to the tool, and are hence commonly termed Freestones, whatever may be their other mineralogical characters, the most desirable, and, therefore, eventually the cheapest, are far from being always employed. " Indeed, it sometimes happens that we find the common cottages built of du- rable materials, while the larger mansions and public buildings are not ; the materials for the latter having been selected because they were readily worked up for the ornamental parts, while those from the former may have been thrown aside in the same quarry, because they yielded less freely to the tool." Report on Cornwall, Devon, and West Somerset, &c. ante cit. p. 485. 454 NEW HOUSES OF PARLIAMENT. obtain, may assist in destroying their surface, and opening the way to a more mischievous, because a deeper-seated, action. The necessity of a due consideration of the nature and qualities of the different building-stones in England was well illustrated by the result of a commission appointed in 1839, with reference to the selection of stone for building the New Houses of Parliament. The Report of the Com- missioners contains, in a tabular form, the only published account of the nature and relative excellence of these materials, and it is, therefore, of great value in that respect to every practical man. Some of the remarks also, in the Report itself, are of considerable interest, and I shall not hesitate to make such use both of these remarks and of the tables as will best advance the object I have in view in the present chapter. The varieties of stone that may be used for buildings may be classed under four very distinct heads, and consist, first, of limestones or carbonates of lime, with more or less admixture of foreign substances ; secondly, of magnesian limestones, or carbonates of lime and magnesia; thirdly, of sandstones; and fourthly, of granites, porphyries, and other igneous rocks, but these latter, when sufficiently hard and compact to resist decomposition, are usually too hard to be used economically in great public works, and they will not therefore require any lengthened description. I. LIMESTONES. Of limestones there are two or three very distinct kinds, each of which is worthy of notice with respect to its Geo- logical position, as well as its economic value. The first of these includes the argillaceous limestones common in ARGILLACEOUS AND CRYSTALLINE LIMESTONES. 455 Silurian rocks, and found also in Devonshire and Cornwall in rocks of th6 Devonian period, but stone of this kind is not confined to any particular Geological localities, being met with also in some beds of the Cretaceous series. The second, and a much more important group of lime- stones for building purposes, comprises those (chiefly of the mountain limestone series) which are crystalline and com- pact, and often of a blue colour. The third series in- cludes the Oolites, (which are the stones most commonly used and the most convenient for ordinary purposes,) abounding in the middle Secondary group of formations, and employed in most of the public buildings that have been erected in the middle, west, and south, of England. These stones, however, vary greatly in relative value as building materials. The argillaceous limestones of the older rocks are so rarely of sufficient durability to be used for public buildings, that there is no quarry of this kind reported on by the Commissioners. They have indeed mentioned only one ar- gillaceous limestone as of tolerable excellence, and this is an accidental variety of the lower chalk quarried at Tottern- hoe, near Dunstable, and formerly used in some kinds of external work, but now superseded by Bath stone. Like other kinds of clunch (as the lower chalk is sometimes called), this bed forms an easily-cut, and a very useful material for certain kinds of internal decorative work, and has often been used for such purposes in the interior of our cathedrals. The crystalline carbonates of lime that have been used for building are not very numerous, although they possess many advantages, among which great durability and resistance to decomposition, may be ranked as the principal. Many of them, however, are too expensive to be generally 456 BUILDING MATERIALS. employed, such as marble and ornamental stones, and the number of fossil remains found in those of Derbyshire and Devonshire sometimes tends to diminish their value by exposing them to unequal decomposition in the parts where the fossils chiefly abound. It is chiefly the Oolitic limestones that have been em- ployed in England for building' purposes ; they are so called from the egg-shaped particles of which they are more or less composed, and these egg-shaped particles being cemented together by a calcareous matter of varied character will, of necessity, suffer unequal decomposition unless the oviform bodies and the cement be equally co- herent, and of similar chemical composition. Of the same Geological period, and associated with the Oolitic limestones, there are also some which are called " Shelly," and these, being chiefly made up of either broken or perfect fossil shells cemented by calcareous matter, also suffer decomposition in an unequal manner, because the shells, being for the most part crystalline, offer the greatest amount of resistance to the decomposing effects of the atmosphere. The shelly limestones have a coarse, la- minated structure, which is usually parallel to the planes of their beds, and when made use of they require to be placed in a building so that the planes of lamination shall be horizontal. The Oolitic limestones best known and most extensively used in England, are the following, viz. : the Portland, the Bath, the Ketton, and the Barnack. Besides these the Caen stone has been a good deal employed in some English buildings of an early date (among the rest in Canterbury Cathedral) and is a stone of great beauty and durability. THE PORTLAND STONE is obtained from a number of quarries in the Isle of Portland. In a former Chapter, PORTLAND STONE. 457 under the head of ' Descriptive Geology,' I have mention- ed the position of this limestone at the top of the Oolitic group of formations, where it appears as a limestone of marine origin, immediately overlaid by freshwater lime- stones and a bed of vegetable mould, belonging to the Purbeck series.* This latter bed (called the dirt-bed) is full of fossil roots, trunks and branches of trees often lying in the position of their former growth. Beneath the dirt- bed, the first bed of stone is called the top-cap, and is a white, hard, and closely compacted limestone, from three to six or seven feet thick ; and to this succeeds the skull- cap, which is also well compacted, but is irregular in its texture, and contains numerous cherty nodules. The skull-cap is not more than half the thickness of the overlying bed, and is succeeded by what are called the roach beds, which are incorporated with the freestone beds below, but are full of cavities, (originally occupied by shells and still occasionally containing casts of them,) and near the upper part are occasional bands of oyster shells and irregular layers of flint. The whole series down to the roach forms the capping of the regular freestone, and the first bed below it, called ' the top-bed,' is the best stone of the quarries. It is fine-grained, and free from shells and hard veins ; it varies considerably in thickness, being sometimes not more than three, but frequently eight feet thick, and it occasionally alternates with roach beds, or, in other words, with beds that have once been fossiliferous, but are now porous and irregular. Below the top bed, in some of the quarries, is a middle, or curf bed, and then a third or bottom bed, similar in appearance to the top bed, and of the same component parts, but the stone is ill- cemented, and will not stand the weather. * See section, vol. i. p. 422. 458 BUILDING MATERIALS. The description above given applies to the stone in its ordinary condition, and when of good quality ; but in most of the quarries, and sometimes in different parts of the same quarry, it varies very considerably. Generally speaking, the stone is inferior, and will not stand the weather, when it contains flints, or when it immediately underlies layers of flints ; while the most durable stone has its cementing matter in a solid and half-crystalline state, and in the least durable kinds this part is earthy and powdery. The shelly parts are considered, on the whole, inferior, but are occa- sionally worked. The Portland stone is well known to be of a whitish- brown colour : its average specific gravity, when dry, is about 2*145, (rather heavier than the ordinary qualities of building limestones,) and it absorbs about one-ninth of its bulk of water. The weight of particles disintegrated after eight days 1 exposure of 2-inch sided cubes to Brard's process,* was found to be 2*7 grains, and its cohesive * The object of this process is to discover in a short time the relative resistance offered by different kinds of stone to the action of damp and frost, and therefore to determine the durability of stones, with reference to exposure. Its accuracy was determined by a number of experiments made in different parts of France and Switzerland, and by different persons, and reports to this effect were published in the Annalesde Chimie for 1828, vol. xxxviii. The following is an abstract of the method recommended to be employed. 1. Several specimens should be selected from the questionable parts of a block of stone to be tried, taking, for instance, those which present differences of colour, grain, or general appearance. 2. These fragments should be cut into two-inch cubes, with sharp edges, and each must be marked carefully, so that the part of the block from which they came may be referred to. 3. There must next be prepared a saturated solution of Glauber's salts (sul- phate of soda), the solution being made with cold water, and a quantity of the salt left for an hour or two at the bottom, after as much has been taken up as the water will at first absorb. (It will be found that a quart of water absorbs more than a pound of this salt at ordinary temperatures.) The saturated solution is then to be boiled, and the cubes prepared are to be plunged into the vessel in which the solution is boiling violently, care being taken that each one of the cubes is completely submerged. The boiling is then to be kept up, and the stones re- PORTLAND STONE. 459 power is moderate. It is composed of upwards of 95 per cent, of carbonate of lime, with a little more than 1 per cent, both of silica and carbonate of magnesia. Portland stone has been much used in the metropolis ; St. Paul's Cathedral and several churches, the Goldsmith's Hall, the Reform Club House, and many other public edifices being built of it. It can be obtained in blocks of almost any required size, and is readily conveyed by water to London. It is, however, not a cheap stone, either as delivered rough, or in working, exceeding in this re- spect most of the common limestones, and some of the magnesian limestones. On the spot, and when exposed only to the open air in the country, it appears to be an exceed- ingly durable stone ; an old church in the neighbourhood of the quarries, built in the fourteenth or fifteenth century, tained in the boiling liquid for half an hour exactly. If a longer period elapses, the effects produced exceed those of ordinary atmospheric action and frost. 4. When the boiling is completed, each specimen is to be withdrawn succes- sively, and suspended from a string, taking care that it touches nothing else, and is completely isolated. Beneath each there is also to be placed a vessel full of a quan- tity of the solution in which it has been boiled, care being taken that it contains no fragments of the stone detached during the boiling. 5. If the weather is not too wet or too cold, it will be found that the surface of the stones four-and-twenty hours after they have been suspended are covered with small, white, acicular crystals of salt. When these appear, the cubes are to be plunged into the vessel below them, to get rid of the efflorescences ; and this is to be done repeatedly, as often as crystals of salt are thrown out during the experi- ment. 6. If the stone resists the decomposing action of damp and frost, the salt does not force out any portions of the stone with it, and one finds neither grains, nor laminae, nor other fragments of the stone in the vessel. If, on the other hand, the stone yields to this action, small fragments will be perceived to separate them- selves, detached even from the first appearance of the salt, and the cube will soon lose its angles and sharp edges. The portions thus detached are preserved at the bottom of the vessel over which the cube is suspended, and their weight may be determined at the completion of the experiment. 7. The period of duration of the experiment, as recommended by M. Brard, should be four days, and at the end of that time the particles detached should be carefully weighed. The result is an index of the amount of disintegration suffered by the stone, and may be compared with similar results from other stones. 460 BUILDING MATERIALS. being in very good condition, and retaining the original chisel marks on its north front. This is the case, also, with the remains of the keep of Bow and Arrow Castle, also in Portland Island, and many centuries old. The ashlar resembles the top bed, and is in perfect condition; and other parts, which appear to be of the cap-bed, are also in good condition.* " As an instance, however, of the difference in the de- gree of durability in the same material, when subjected to the effects of the atmosphere in town and country, may be noticed the frustra of columns, and other blocks of stone, that were quarried at the time of the erection of St. Paul's Cathedral in London, and which are now lying in the Island of Portland, near the quarries from whence they were obtained. These blocks are invariably found to be covered with lichens, and although they have been ex- posed to all the vicissitudes of a marine atmosphere for more than one hundred and fifty years, they still exhibit beneath the lichens their original form, even to the marks of the chisel employed upon them ; whilst the stone which was taken from the same quarries, (selected, no doubt, with equal, if not greater care, than the blocks alluded to,) and placed in the Cathedral itself, is, in those parts which are exposed to the south and south-west winds, found in some instances to be fast mouldering away."-f- THE BATH STONE, which, like the Portland, is one of those most commonly used and most admired for public buildings in England, is obtained from three principal local- ities, two of them in Wiltshire, and one in Somersetshire. * The new church in the island of Portland, built in 1766, of the variety of Portland stone called Roach, is in an excellent state throughout, even to the preservation of the marks of the chisel. t Report, &c. p. 5. BATH OOLITE. 461 Its Geological position is in the lower part of the Oolitic series. It is more perfectly oolitic in its structure than the Portland stone, and has a rich cream colour. It is moderately fine-grained, is composed of about 941 per cent, of carbonate of lime, and 2^ per cent, of carbonate of magnesia, but no silica : its specific gravity is 1*839, nearly one-seventh less than that of Portland stone, its cohesive power is only 21, and the number of grains lost by disintegration by Brard's process is as much as ten. It absorbs nearly one-third of its bulk of water. Some of the most ancient quarries of the Bath stone are on the escarpment of the Oolite at Box Hill : there is here a total thickness of forty-five feet of workable stone, con- sisting of from 12 to 15 feet of scallet, which is the finest grained, and is cut for ashlar : 1 5 to 20 feet of corn-grit, used for dressings ; and from 16 to 22 feet of ground-stone. Nearer Bath, at Coombe Down, are several quarries worked in three beds, whose total thickness is about seven feet, and the stone is there applied, amongst other uses, in the manufacture of troughs. Other quarries are worked, also, near Bath, in which there is about 20 feet of workable stone, some beds of which are much employed in coarse sculpture. These latter quarries are all subterranean. The Bath Oolite is a stone of great beauty ; it works very freely in the quarry, (some of the beds cutting almost as readily as chalk,) and hardens on exposure to the air, it is exceedingly cheap, both as delivered rough and in the after working, and may be obtained of almost any ordinary dimensions, but it certainly cannot be recom- mended as a durable stone. The Abbey church of Bath, built of stone from the neighbouring quarries, is partly in fair condition, but the body of the church, in the upper part of the south and 462 BUILDING MATERIALS. west sides, is much decomposed. Its date is 1576. Where it has been defended by buildings formerly in contact with it, the stone in this building is in a better state, but the reliefs and other ornaments are nearly effaced. Other buildings, not much more than a century old, are also in fair condition, but exhibit marks of decomposition on the west and southern aspects.* In the Inferior Oolites at Doulting, in Wiltshire, a bed of shelly limestone has been long quarried, and appears to possess many excellent qualities. It is a carbonate of lime, with a few oolitic grains, and an abundance of small shells, commonly in fragments, and often crystalline : its colour is light brown, its specific gravity considerably greater than that of either of the quarries of Bath stone, and it occurs in four or five beds, whose total thickness is about ten feet, but there are ancient quarries in the neigh- bourhood where a greater depth of stone is found. Most of the public buildings in Wells arid Glastonbury and the neighbourhood, are of this stone, and the exten- sive Norman ruins of Glastonbury Abbey, some of them of the eleventh century, are in good condition, the zigzag and other Norman enrichments being perfect. The cathedral of Wells, chiefly of the thirteenth and fourteenth centuries, is also built of similar stone, and although partially decom- posed, is in good condition, especially on the south side, and in the central tower. The Chapter House, built in the thirteenth century is in good condition, except the west front, which is decomposed. THE KETTON STONE and the BARNACK RAG are both of them admirable building-stones, obtained from the lower * Henry the Seventh's chapel, in Westminster Abbey, restored about twenty- five years since with Coombe Down Bath stone, is already in a state of decompo- sition. BARNACK RAG. 463 Oolitic strata of Rutlandshire and Northamptonshire. The Ketton is a very even grained stone, (the oolitic grains being of moderate size,) and of a dark cream colour, rather streaky when first exposed, but weathering evenly and paler. It contains rather more than 92 per cent, of carbonate of lime and upwards of 4 per cent, of carbonate of magnesia. Its specific gravity is 2' 045, and its loss by disintegration 3*3 grains. It absorbs about one fourth part of its bulk of water, and its cohesive power is much greater than that of any other Oolite. It consists of two beds, the hard upper bed, called ' Ketton rag,' being about three feet six inches thick, and the principal mass containing about four feet of Oolite in one or two beds. It is an expensive stone, but worked more easily than Portland. This stone has been much used in the middle of Eng- land, and in the metropolis; many of the buildings in Cam- bridge are constructed of it, all of which are in excellent condition ; and it has been greatly employed in the modern buildings both in Ely and Peterborough Cathedrals. The Barnack stone belongs rather to the shelly lime- stones than to the true Oolites, but it is obtained from beds of the same Geological age as the Ketton stone. The colour of Barnack rag is a light whitish brown ; it consists of 93*4 per cent, of carbonate of lime, and 3'8 per cent, of carbonate of magnesia ; it is partly oolitic, but compact and coarsely laminated with shells and frag- ments of shells. It is a very little heavier than Ketton stone (S. G. 2*090) but its rate of disintegration by Brard's process is five times as great, and its cohesive power not more than two thirds. It is, however, a most excellent stone, several buildings of the twelfth and thirteenth cen- tury built of it being in admirable condition, and scarcely at all decomposed. It is the material that has been used 464 BUILDING MATERIALS. in the greater proportion of the churches in Lincolnshire and Cambridgeshire, and it has the advantage of being tolerably cheap. There are besides these many other limestones in dif- ferent parts of the country, and of the Oolitic class, which have been locally used, and have been found to possess advantages, greater or less, according to circumstances. Amongst these, I ought perhaps to mention the Oolite of Ancaster, in Lincolnshire, which has been much em- ployed in that county, and of which the lofty tower and spire of Grantham Church (built in the thirteenth century) is an excellent example. The remarkable siliceous limestone of Chilmark, in Wiltshire, is also worthy of notice for its extremely great cohesive power (nearly three times as great as that of any of the carbonates of lime without silica) and its consider- able specific gravity (2- 481), in which latter respect it is only inferior to the nearly pure siliceous rock of Darley Dale, in Derbyshire. It contains nearly 80 per cent, of carbonate of lime, more than 10 per cent, of silica, and 3-j per cent, of carbonate of magnesia. Salisbury Cathe- dral is built of this stone, and is in excellent condition, except the west front, which is in parts slightly decom- posed. It must not be forgotten while considering the relative disintegration of these different limestones, that those which have a coarse laminated structure, such as the shelly beds, may be exceedingly durable if (as should always be done) care is taken to place them in the building parallel to the planes of the beds. The decomposition, which is exceed- ingly rapid when the planes of the laminae are exposed, can scarcely even commence at the edges. 465 CHAPTER XIII. APPLICATION OF GEOLOGY TO ARCHITECTURE, Continued. MAGNESIAN LIMESTONE. SANDSTONES. CAUSES OF DECOM- POSITION OF DIFFERENT BUILDING STONES. UNSTRATIFIED ROCKS. II. THE MAGNESIAN LIMESTONES. THE magnesian limestones vary in quality even more than the carbonates of lime, and require, therefore, to be selected with still greater care and consideration when they are to be employed for building purposes. They are strictly confined in their distribution in England to the newer beds of the Palaeozoic period, and they overlie the lower beds of the lower New red sandstone, being separated by those strata from the coal measures. They are rarely quarried except in the counties of Derbyshire and Yorkshire. The magnesian limestones have not hitherto been much used at a distance from the quarries, and their excellent qualities as building stones hardly seem to have been generally recognised till it was determined to recom- mend one of them for the new Houses of Parliament. They are chiefly obtained from four principal localities, and it will be most convenient to consider these in their geographical order, beginning with Bolsover, in Derby- shire, the southernmost, and proceeding northwards to the VOL. II. 2 H 466 BUILDING MATERIALS. others, which are respectively in the vicinity of Bawtry, Doncaster, and Tadcaster, in Yorkshire. The Bolsover quarries (from which the stone for the new Houses of Parliament is procured), and several others that have recently been opened in the neighbourhood, contain about twelve feet of workable stone, in numerous bands from eight inches to two feet thick. This stone is of a light yellowish brown colour, which does not appear to change by exposure. It has a pearly lustre when broken, and a peculiarly beautiful semi-crystalline structure. Its chemical composition consists of 51 per cent, of carbonate of lime, 40 per cent, of carbonate of magnesia, and more than Big per cent, of silica. Its specific gravity is 2*316, or considerably greater than that of any other limestone, and its cohesive power is nearly four times as great as that of Portland stone, and very much greater than that of any other limestone or sandstone examined by the Commissioners. Its disintegration also was found to be exceedingly small. This admirable stone is not expensive, being cheaper than Portland stone, and worked as easily, but it does not seem to have been much used at a distance from Bolsover, except in slabs for paving. Its qualities of durability are well tested in Southwell Church, Nottinghamshire, a build- ing of the tenth century, and in admirable condition. In this church the Norman portions, built of stone similar to that of Bolsover Moor, are throughout in a perfect state, and the mouldings and carved enrichments are as sharp as when first executed. The Roche Abbey quarries near Bawtry, in Yorkshire, exhibit another instance of semi-crystalline magnesian lime- stone, but the quality is not at all equal to the stone of Bolsover Moor, and, although thick, the stone is so irregu- MAGNESIAN LIMESTONES. 467 Jarly bedded as to give no certainty as to large blocks. This stone contains only 39^ per cent, of carbonate of magnesia and 57^ of carbonate of lime, and it is both the lightest and the least cohesive of all the magnesian limestones. It would appear that " the nearer the magnesian lime- stones approach to equivalent proportions of carbonate of lime and carbonate of magnesia, the more crystalline and the better they are in every respect." 4C ~ In spite of the imperfections of the stone however in this respect, Roche Abbey, built of it in the thirteenth century, is said to exhibit generally a fair state of preservation ; but this is accounted for by its semi-crystalline condition and the resistance which the stone therefore offers to the decom- posing action of the atmosphere. But some portions of the building have, notwithstanding, yielded to the effects of the atmosphere and exhibit marks of decomposition. There are two considerable magnesian limestone quarries in the neighbourhood of Doncaster, from both of which building stone has been obtained, though they appear to differ very considerably in value. The Brodsworth quar- ries produce a friable stone, with a tendency to oolitic structure ; the thickness of the beds is considerable, the price low, and blocks of great size can be procured ; but it has not stood the test of time. The old church of Doncaster, built in the fifteenth century of this stone, is so much decomposed, that it is now undergoing general and extensive repair. The Park-nook quarries yield a much better stone than those of Brodsworth, and contain about fifteen feet of workable material, which may be obtained of any prac- ticable size. There are buildings of this stone about a century old in perfect condition ; and it is considered * Report, &c. p. 7. 2H2 468 BUILDING MATERIALS. by the Commissioners worthy of being recommended as a desirable building material. It is of a cream colour, and partly crystalline. The Huddlestone quarries, and others in the neighbour- hood of Sherburne, supply also a good semi-crystalline magnesian limestone of a whitish cream colour, which has been very much and very long used for building purposes, and of which, indeed, ' Westminster Hall ' is built. Jack- daw Craig, near Tadcaster, and Smawse, in the same neighbourhood, are also well known for their quarries, which have supplied the stone for public buildings in many parts of Yorkshire. The stone from Jackdaw Craig was employed in the building of York Minster, the transepts of which date from the thirteenth, and the tower, nave, &c. from the fourteenth century ; but, from the generally decomposed state of all this stone, more especially in the mouldings and enrich- ments, it is evidently not one that should be selected for durability. It is of a dark cream colour, not very crystal- line, and it lies in irregular beds, varying from a few inches to three feet in thickness. The upper beds, which are the worst, have been the most quarried, and many of the churches of York, besides the Cathedral, are proofs of the want of judgment in the architect who selected a material so readily injured by exposure. The Smawse quarries on Bramham Moor, contain a stone slightly crystalline, and probably for that reason more durable than the former. It is not, however, very greatly to be depended on, as in Beverley Minster, (twelfth, thirteenth, and fourteenth centuries) the west tower, central tower, and other parts built of this stone are in good condition, while in other parts of the build- ing the same material is decomposed. The ancient parts SANDSTONES. 469 of St. Mary's Church at Beverley, supposed to have been partly built of the Bramham Moor stone, are also in a very crumbling state, even to the total obliteration of many of the mouldings and enrichments. The Huddlestone stone, however, which is much more perfectly crystalline, is also a more uniformly excellent building material. Huddleston Hall, built in the six- teenth century of this stone, is in excellent condition, exhibiting in perfect preservation the mouldings of a window in the south-west front ; and a church at Hem- mingborough, of the fifteenth century, and constructed of a material resembling the stone from Huddlestone, does not exhibit any appearance of decay. III. SANDSTONE. The number of the different kinds of sandstones that have been used for building purposes is so great, and their qualities vary so indefinitely, that it is no easy matter to place them before the reader in such order that he shall perceive the general conclusions that may be derived from the investigation. I will endeavour, however, to bring them together into groups, and exhibit in this way the result rather than any detailed account of particular beds. Sandstones have been selected for building purposes from the whole series of formations, including the oldest Palaeozoic and the most modern Tertiary rocks, but it is chiefly those obtained from the older rocks that have been worked on a large scale, and to a great extent. This is so much the case, indeed, that of the whole number of quarries of sandstone (amounting to sixty-three) visited and reported on by the Commissioners, as many as fifty 470 BUILDING MATERIALS. were from the Palaeozoic rocks, thirty-seven of them being from the Carboniferous system, and the remain- ing thirteen from the Old red sandstone. Perhaps the most convenient method of considering these different stones will be to group them according to their Geo- logical position. Of the sandstones of the Middle Palaeozoic period there are two very striking varieties ; the first obtained from the beds of the Old red sandstone, running up through the counties of Stirling, Perthshire, and Forfarshire in North Britain, and from a fragment of the same bed on the coast of Rosshire ; and the second, from the very different beds of the same age in Monmouthshire. The former stone, chiefly shipped from Dundee, is of moderately fine grain, of a purplish grey colour, micaceous in the plane of stratification, and composed of siliceous grains, united by a calcareo-argillaceous cement, which is sometimes also siliceous. The stone lies in beds of from three to six feet thick, and exhibits a total thickness of fifty or sixty feet. It is very heavy and close-grained, and has been long and extensively used in the neighbourhood in which it is found, but is rather expensive to work. The Stirlingshire beds differ from the Forfarshire in their colour, which is a whitish grey, in the absence of calcareous matter in the cement, and also in the thickness of the beds, which is considerably less. The Perthshire beds re- semble the Stirlingshire rather than the Forfarshire varieties, but the cementing material, although princi- pally siliceous, is mixed with oxide of iron, instead of with argillaceous matter. All these stones are good and durable. The Old red sandstone of Monmouthshire is quarried near Chepstow, and was employed in the erection of CARBONIFEROUS SANDSTONES. 471 Tintern Abbey. The bed is of a light greyish brown colour, of an irregular grain, cemented by an argillo-sili- ceous cement, and containing ferruginous spots, and occa- sional plates of mica. It is in beds, the thickest of which varies from ten to twelve feet. Tintern Abbey is in unequal condition, but the stone is for the most part per- fect ; it is covered with lichens. The sandstones of the Carboniferous system belong chiefly to the uppermost beds of the group, and there are few places where some tolerably good building-stone may not be obtained if these upper beds predominate. The carboniferous sandstones of Craigleith and other quarries in the neighbourhood of Edinburgh, and the county of Linlithgow, in Scotland, have been much used, and are some of them of excellent quality. They are generally of a lightish grey colour, fine grained with a sili- ceous cement, slightly calcareous, and containing a little mica in the planes of bedding. The Craigleith stone con- sists of 98^ per cent, of silica, and little more than one per cent, of carbonate of lime ; it is not a very heavy stone, and its cohesive power is second only to the magnesian limestone of Bolsover. It has been used extensively of late years in public buildings at Edinburgh, and also for landings, steps, and pavings in London, and has stood ex- ceedingly well. The beds of it vary much in thickness, the thickest being ten feet ; but there are about 200 beds in all, and the whole depth of rock quarried is as much as 250 feet. It is rather an expensive stone, and more difficult to work than Portland stone. The quarries at Uphall, in Linlithgowshire, also supply a good material, much used in some of the modern buildings in Edinburgh. It is not so heavy, nor is its cohesive power so great, as the Craigleith stone. 472 BUILDING MATERIALS. The coal grits used for building purposes, and which are obtained from the neighbourhood of Glasgow, are not so uniformly good as those near Edinburgh. The ' Giff- neuch 1 quarries contain about twenty-two feet of good rock, and twenty feet of inferior, but in the c President' quarries, where the stone is exceedingly thick, it is porous, uneven in tint, and although at first of a pale brownish grey, soon assumes a foxy colour. The sandstones in both are fine grained; in the former (the Giifneuch) the grains are cemented by a calcareo-siliceous, and in the latter by an argillo-siliceous matter, and both of them are micaceous. Of the ancient buildings of Glasgow, the High Church, built in the twelfth century, of sandstone from the neigh- bourhood, is very much decomposed, particularly on the south side, and the old quadrangle of the college (of the time of James II.) is also decomposed. Of the modern buildings, the Hunterian museum (1804) said to be of stone from the President quarry, exhibits traces of decom- position, but it is built of different stones, some of which are much changed, and some almost perfect. Several build- ings erected of stone from the Giffneuch and other quarries in the neighbourhood, are quite perfect. The coal grits of the Newcastle coal-field have been the chief building-stones used in Newcastle, Durham, and the other towns of the district. In the neighbourhood of Newcastle several quarries are worked, amongst which are the Heddon and Kenton ; both of these contain stone of a palish brown, or grey colour ; the quartz grains are united by an argillo-siliceous cement with iron, and the beds are of variable thickness and quality. It would appear from the condition of the buildings that have been erected of these stones, that they are extremely liable CARBONIFEROUS SANDSTONES. 473 to decomposition, and this is not to be wondered at, since their cohesive power is small, their rate of disinte- gration, measured by Brard's process, very rapid, and they absorb nearly one-fourth part of their bulk of water. They are very bad specimens of the group of stones to which they belong. Although, however, the coal-grits of Newcastle are so indifferent, some of the carboniferous rocks found in the county of Durham, a little further to the south, offer better examples of building materials, while others again, such as those of which Durham Cathedral is built, are quite as decomposable as the Newcastle stones. The colour of most of the sandstone quarried in the neighbour- hood of Durham is a pale whitish brown, with ferruginous stains, and the quartz grains are cemented with an argillo- siliceous cement, partly derived from decomposed felspar. Plates of mica are also found distributed through the stone. The Stenton quarries, near Barnard Castle, supply an ex- cellent material, and of this the circular keep of Barnard Castle (of the fourteenth century) is built. It appears to be in perfect condition.* It would seem from these differ- ences that in this part of the North of England the sand- stones of the millstone-grit are better adapted for build- ing purposes than those of the coal measures, for the only good quarries recorded are in the former series, and the worst are all in the latter. The millstone-grit quarried at Gatherly Moor, near Richmond, in Yorkshire, is of a cream colour, and made up, like the Stenton beds, of moderate-sized quartz grains, * Eccleston Abbey, Yorkshire, (of the thirteenth century,) is built of stone similar to that of the Stenton quarry, and the mouldings, and other decorations, such as even the dog's-tooth enrichments, are in perfect condition. 474 BUILDING MATERIALS. united by an argillo-siliceous cement. The keep of Bich- mond Castle (of the eleventh century) built of sandstone of this kind, is in good condition, and the mouldings and carvings in the columns of the windows are in a perfect state. There have been a number of quarries opened in the neighbourhood of Leeds, all of them in the coal measures, and these supply a coarsish-grained sandstone with argillo- siliceous cement, having plates of mica in the planes of the beds. It is not likely that they will prove of very durable quality, but there is no account of their having hitherto shewn symptoms of decay in the various public buildings of the town. In various parts of Yorkshire and in Derbyshire, wherever the sandstones of the coal measures and the mill- stone-grit have been used for building purposes, they are found to exhibit nearly the same general character and local differences as those already described in other parts of England further to the north. The coal-grits are usually decomposable, and, perhaps, as a general rule, more so than the millstone-grits. A whitish or reddish-brown stone, belonging to the Lower New red sandstone formation, and consisting of fine siliceous grains, with magnesio-calcareous cement, is quarried at Mansfield, in Nottinghamshire, and appears to form a tolerable building-stone, shewing no signs of decomposi- tion in those buildings that have been hitherto erected of it. The New red sandstone near Stafford, and in some other places, has been occasionally quarried for building purposes, but it is rarely sufficiently indurated to serve even for those of the commonest kind. The Lias, like the New red sandstone, although for a very OOLITIC SANDSTONES. 475 different reason, rarely offers any valuable building material, and in most cases is totally inapplicable even for the com- monest purposes. It has, however, been sometimes used, as for instance, in portions of Glastonbury Abbey, where several lias columns and capitals are to be found, but they are nearly mouldered away although from those parts which remain the material employed seems to have been of the most compact kind. Returning, however, to the sandstones, we again find them overlying the lias and occupying the lower part of the Oolitic group of formations, as exhibited in the north of England, on the Yorkshire coast, where several sandstone beds have been much worked near Whitby, supplying an admirable building-stone, shipped to many parts of England. This stone is of a colour varying from pale to rather dark brown, but it has sometimes a warm tint. It is extremely light, its specific gravity being less than that of almost any other sandstone. It occurs in beds of considerable thickness, and can be obtained of almost any required size, and it is inexpensive and works freely. Of ancient buildings of this stone, Whitby Abbey, of the thirteenth century, may be cited, and it is generally in good condition, with the exception of the west front. The stone used in the Abbey is of two colours, brown and white, and the former is in all cases more decomposed than the latter, a fact which is doubtless owing to the presence of a larger per centage of iron. A very large number of modern buildings, not only in the neighbourhood of Whit- by, but in London, Cambridge, and even so far distant as Exeter, are constructed of material obtained from the Whitby quarries, and they are all of them at present in excellent condition. 476 BUILDING MATERIALS. With regard to the sandstones of formations more modern than the Oolites, but few of them are used in England for building purposes, except very locally. Among those, however, most worthy of notice, is a stone obtained from the Hastings Sand, at Calverly, Tunbridge Wells, which has been much employed of late years in the neigh- bourhood, and which, from its cheapness, variegated colour, and the facility of procuring large blocks, offers many ad- vantages. It yet remains to be seen how far it can be considered a durable stone. The upper beds of the greensand are quarried at Gatton, near Merstham, in Surrey, and supply a fine-grained stone, with a calcareo-siliceous cement, of a greenish light-brown colour, sometimes used for building purposes. It is, how- ever, liable to decomposition, and, except when very care- fully selected, and placed in the building with reference to its position in the bed, it offers little resistance to the action of the weather. The beds of the Tertiary period in England, being chiefly composed of clays and loose sands, can only be used for building purposes when converted into brick. The only exceptions to this condition consist of a fresh- water lime- stone worked at Binstead, near Ryde, in the Isle of Wight, and some unimportant argillaceous sandstones at Bognor and elsewhere. I have now completed my account of those kinds of stone that are most likely to be selected for public build- ings, and which are obtained in our own country ; and several observations suggest themselves with regard to the different qualities of these stones, and their relative dura- bility under certain circumstances of exposure ; while a general resemblance may be traced in the qualities of stones deposited under similar Geological conditions. RATE OF DECOMPOSITION. 477 With respect to the decomposition of stones employed for building purposes, it is greatly influenced, as well by the chemical and mechanical composition of the stone itself and by the nature of the aggregation of its compo- nent parts, as by the circumstances of exposure. The Oolitic limestones will thus suffer unequal decomposition, unless the little egg shaped particles, and the cement with which they are united, be equally coherent, and of the same chemical composition. The shelly limestones, or ' rags,' being chiefly formed of fragments of shells, which are usually crystalline and cemented by a calcareous paste, are also unequal in their rate of decomposition, because the crystalline parts offer the greatest resistance to the decom- posing effects of the atmosphere. These shelly limestones have also, generally, a coarse laminated structure, parallel to the plane of stratification, and, like sandstones formed in the same way, they decompose rapidly when used as flags, where their plane surfaces are exposed ; but if their edges only are laid bare, they will last for a very long and al- most indefinite period. Sandstones, from the mode of their formation, are very frequently laminated, and more especially when micaceous ; the plates of mica being generally deposited in planes pa- rallel to the beds. Hence, as I have just observed, if such sandstone, or shelly laminated limestone, be placed in buildings with the planes of lamination in a vertical position, it will decompose in flakes, more or less rapidly, according to the thickness of the laminae; whereas, if placed so that the planes of lamination are horizontal, that is, as in its natural bed, the edges only being ex- posed, the amount of decomposition will be comparatively immaterial. The sandstones being composed of quartzose or siliceous grains, comparatively indestructible, they are 478 BUILDING MATERIALS. more or less durable according to the nature of the ce- menting substance ; while, on the other hand, the lime- stones and magnesian limestones are durable in proportion rather to the extent in which they are crystalline ; those which partake least of the crystalline character, suffering most from exposure to atmospheric influences. " The chemical action of the atmosphere produces a change in the entire matter of the limestones, and in the cementing substance of the sandstones, according to the amount of surface exposed. The mechanical action due to atmospheric causes, occasions either a removal or a disruption of the exposed particles ; the former by means of powerful winds and driving rains, and the latter by the congelation of water forced into, or absorbed by, the ex- ternal portions of the stone. These effects are reciprocal, chemical action rendering the stone liable to be more easily affected by mechanical action, which latter, by constantly presenting new surfaces, accelerates the disintegrating ef- fects of the former." On the whole, it would appear that, where there are no local reasons to the contrary, preference should be given to limestones over sandstones for most public buildings intended to be handed down to future ages ; and this on account of their more general uniformity of tint, their comparatively homogeneous structure, and the facility and economy of their conversion to building purposes. Amongst the limestones, also, those which are most crystalline are to be preferred ; and some of the magnesian limestones seem to offer the greatest advantages of durability, uni- formity of structure, beauty of appearance, and facility of conversion ; but it should be clearly understood, that many other limestones, and many sandstones, also form admir- able building stones, and these are so distributed through UNSTRATIFIED ROCKS. 479 the country, that there is now no excuse for those archi- tects and engineers who neglect to examine carefully into the relative durability and excellence of the stone employed in any edifice about to be constructed. It might also easily be shewn, that if more attention had been paid to these various qualities of the stone made use of in buildings, the frequent decay or decomposition, observ- able in many of those which have been erected even within a few years, might have been avoided, at comparatively small cost, and we should find fewer of our public edifices losing all traces of the finer work of their original struc- ture. So long, however, as the opinion and judgment of the mason is allowed to decide on the stone to be used, so long will this unpardonable result take place, for " the mason almost always judges by the freedom with which a stone works, no doubt an important element in the cost of a building, but certainly one which should not be per- mitted to weigh heavier in the scale than durability, and hence many a fine public or large private building is doomed to decay even, in some cases, within a few years." * Although the unstratified rocks are not very often em- ployed in the construction of public edifices, because, when not decomposable, they are usually of extreme hardness, they still require to be considered among building mate- rials, and are occasionally selected for bridges, public monuments, &c., and sometimes for ornamental work. The principal material of this kind used in England con- sists of granite chiefly obtained from Cornwall and Aber- deen, both of which places offer considerable abundance of excellent stone, varying in colour, texture, and dura- bility. The Cornish granite has been exported chiefly * De la Beche's Report, &c., ante cit. p. 486. 480 BUILDING MATERIALS. from Penryn, at the rate of upwards of twenty thousand tons yearly. The Aberdeen granite is also very exten- sively worked, and resists exposure apparently almost as well as the ancient Syenite of Egypt. Both are more frequently used for road-making than as building mate- rials, although their great beauty and the high polish of which they are capable renders them admirably adapted for the latter purpose, especially for internal decorative work. The Isle of Jersey also supplies an excellent granite of a beautiful flesh-colour, and tolerably durable. The Granites, or rather Syenites of the Malvern Hills and Charnwood Forest, in Leicestershire, are only used locally. ST. HELEN'S BAY, ISLE OF JERSEY. 481 CHAPTER XIV. THE APPLICATION OF GEOLOGY TO AGRICULTURE. THE FORMA- TION OF SOILS, AND THE MIXTURE OF SOILS. CONSIDERING the applications of Geology to practical sub- jects as comprised under the three great subdivisions of Mining, Architecture, and Agriculture, and having already spoken of those operations which are carried on beneath the earth's surface, and which belong to the art of Mining ; and those in which the surface of the globe is made use of as a basis on which the works of Engineering and Archi- tecture depend ; so now, in the third place, I have to direct the reader's attention to the materials which compose the outer coating of vegetable soil upon the earth, and the de- pendence of these on its geological structure, and on the actual physical condition of the strata, and groups of strata, already described. It is this subject to which the name of "Agricultural Geology " more particularly belongs ; but this title includes, also, a number of incidental matters, upon a proper understanding of which the right cultiva- tion of the land depends. Viewing the subject of Agricultural Geology in all its bearings, it may I think be properly and conveniently con- sidered under three heads, each one of which in turn will be found well worthy of careful attention. Under the first of these heads we may discuss the actual nature of vegeta- ble soil in different geological districts, and the circum- stances under which it has been derived from the sub- VOL. II. 2 I 482 AGRICULTURAL GEOLOGY. jacent or other rocks. The second head has reference to the physical as well as geological structure of the earth's surface, and to the nature of the underlying strata, and in- volves the consideration of drainage; while under the third must be discussed the geological conditions involved in the supply of water to the surface by means of springs and wells, and the artificial methods that may be adopted to discover and render available for the use of man those great subterranean reservoirs of water often existing in the bowels of the earth. In the present chapter I shall con- fine myself to a description of the modifications that the agriculturist may effect on the natural soil of a district by availing himself of the means of improvement afforded by Nature, and suggested by a knowledge of Geology. In following out this plan it will be found that most of the interesting facts in Agriculture, to which attention has been so especially paid of late years, will require to be dis- cussed. I shall endeavour, in the first place, to shew the importance of attending to the geological structure of a dis- trict by explaining the origin and use of soils, and of the subsoil, and by stating shortly the different conditions that must be fulfilled in order that land may be fertile. I shall then mention the facts hitherto determined with respect to the principal constituent elements of fertile soils, and their relative preponderance and value in each one of the princi- pal groups of strata of which the earth's crust is composed ; and I shall conclude by directing attention to the bearing of the subject on the valuation of land, and the benefit of geological knowledge to the land-agent and the surveyor. The actual mineral substances of which soils are made up are exceedingly few and simple, consisting of a consider- able proportion of silica, more or less alumina and car- bonate of lime, and a small quantity of magnesia ; but these MINERAL COMPOSITION OF SOILS. 483 are associated with a variable, although never very large, proportion of carbon, chiefly furnished by the decay of vegetable and animal matter, without which no vegetation that is useful to man can be supported. It is, indeed, owing to the presence of carbon, (which in the state in which it is found in vegetable soils is called humus?) that actual fertility is communicated to the otherwise barren mineral particles of which the soil is chiefly composed ; but the main substance of the soil, and those materials by means of which the organic ingredients are rendered avail- able, must in all cases have been derived from the degrada- tion of the subjacent rock, or from the degradation of some other rock, which has been brought there by the action of running water, or by the labour of man.* Beneath the soil, with its usual proportion of decayed organic matter, there is also in most cases a layer, of some- what similar mineral composition, lying below ordinary ploughing, but of great use in promoting the fertility of the land. This is called the subsoil, and it affords a basis into which the roots of trees can penetrate, and whence they obtain an amount of nourishment proportionate to their size. Like the soil itself, it acts chiefly mechanically, and it is of the most vital importance with reference to the drainage of the land. " An impervious clayey subsoil re- tains the surface water in the soil, and thereby renders it * The fertility of the soil is generally supposed to depend on the presence of a peculiar substance, to which the name humus has been given. Humus, it would appear, is nothing more than woody fibre in a state of decay, and it acts in the same manner in a soil permeable to the air as in the air itself. The property of woody fibre to convert surrounding oxygen gas into carbonic acid diminishes in proportion as the decay advances ; and at last a certain quan- tity of a brown, coaly-looking substance remains, in which this property is entirely wanting. This substance is called mould, and is the produce of the complete de- cay of woody fibre, and in this state it is an excellent vehicle, conveying freely to the roots of vegetables the nutritive matter on the surface which is carried down by the rain. Liebig's Organic Chemistry of Agriculture, p. 46. 2 i 2 484 AGRICULTURAL GEOLOGY. wet, cold, and unproductive ; while, on the contrary, when the subsoil is too open, the soil is so effectually drained of its moisture that the plants languish for want of the me- dium by which their food is conveyed to them."* It may readily be shewn that the subsoil is immediately, and the soil intermediately, derived from the decomposition of the subjacent rock, so that in any case the fertility of the land depends on the geological structure of the district. It would, also, be easy to shew that, by taking advantage of the presence of certain mineral substances beneath the surface, a soil naturally barren may often be rendered fer- tile. The whole subject of mineral manures consists in the proper employment of such substances as may counteract the injurious qualities of a barren or poor soil, and either supply the want of some indispensable element of the plant to be cultivated, or prepare the soil to receive those at- mospheric influences which are essential to the development of vegetable life. FORMATION OF A SOIL BT THE DECOMPOSITION OF THE UNDERLYING ROCKS. CLIGGA HEAD, PERRANZABULOE. 1. Firm granite. 3. Thin layers of decomposed granite. 2. Head of rubble, 4. Coarse granitic grit, clay and stones. 5. Black granitic soil. The above diagram offers a remarkable instance of the formation of a soil by several gradations, proving the exist- ence of a powerful denuding force, which has formerly moved over a large portion of the earth's surface. The whole section includes about nine feet, and indicates a * Whitley's Agricultural Geology, p. 75. This work contains a number of admirable practical details, likely to be of great value to the farmer and the land- agent. FORMATION OF MOULD. 485 series of successive operations, the result of long-continued aqueous action ; but, although such an appearance is not uncommon, it must not be supposed that it is invariable, or that a violent rush of water is necessary for the formation of a soil. Bain penetrating into the crevices of an exposed rock, and succeeded by frost, crumbles down the hardest materials, and, if these crumbled portions are washed away, they are rapidly succeeded by others, so that a soil is form- ed, which at length, under favourable circumstances, be- comes covered by mosses and lichens, and from their decay is obtained that supply of carbon and other materials which in process of time renders the soil fit for the growth of other vegetables which are useful to man. In either case, however, the result to the agriculturist is the same, for there is a superficial coating of mould, and a subsoil chiefly or entirely mineral between the mould and the parent rock. 1 * An examination of the soil, and a chemical analysis of it, will in most cases immediately shew that the soil, as well as the subsoil, are derived from the underlying rock ; and it seems that this extends even to the colour, which is white in chalky soils, red on the New red sandstone and the ochraceous beds of the greensand, and yellow on the clays and clay-slate, &c. : but it will not be expected that these conditions should hold when there is a thick bed of super- ficial detritus, such as gravel ; for the gravel must then be looked upon as the parent rock, and the condition of the soil will be little influenced by the actual underlying bed. There are one or two general principles with regard to this part of the subject, which it may be worth while here to enunciate, but which it will not be necessary to enlarge upon or illustrate. * The amount of organic matter required to give fertility to a soil varies from three to ten per cent. 486 AGRICULTURAL GEOLOGY. The depth of a soil is chiefly dependent on the nature of the subjacent rock, and on its ready decomposability by atmospheric agents. The texture of a soil also depends on the parent rock as to whether it shall be loose and gritty, or tough and clayey, and varies according to the tendency of the rock to decompose and the manner in which it is affected by decomposition. The fertility of a soil depends partly on its depth and texture, and partly on its possessing those mineral consti- tuents which enter into the structure of the plants to be grown upon it. The use of the soil in enabling plants to grow is twofold : first mechanical, the soil affording the plant a firm founda- tion, and enabling its roots to take up certain quantities of organic and inorganic substances necessary for its nutri- ment; and secondly chemical, inasmuch as all plants, with- out exception, possess a certain amount of inorganic as well as organic constituents, which after undergoing decom- position and entering into new combinations are taken up from the soil, and assimilated for the use of the living vegetable. These substances are required, also, to be present in the soil in such a state that the roots of the plants are able to absorb them. Liebig states that it is distinctly proved, in analyses made by De Saussure and Berthier, that the nature of a soil exercises a decided influence on the quantity of the different metallic oxides contained in the plants which grow upon it ;* but it does not follow thence that the actual quantity of alkaline bases varies ; and it appears, on the contrary, from other investigations, that the total amount of oxygen united to these bases is always the same * Organic Chemistry, p. 95. USE OF THE SOIL IN VEGETATION. 487 in the same plant, and therefore that the proper quantity of some of them as bases is essentially necessary ; the growth of the plant being arrested when these substances are wanting, and much impeded when they are deficient. The alkalies are often supplied to the soil by rain-water, where they are certainly present, although it is not known in what form they exist. Besides these mineral substances, and some others, the presence of carbon is absolutely ne- cessary, as I have before mentioned ; and the action of the weather, the absorption of rain-water, and, above all, the chemical changes constantly going on in the process of gradual oxidation, (the oxygen being obtained from the atmosphere,) effect the necessary alterations in the dif- ferent constituents of the soil, and render it fit to support vegetable life.* It will now be seen in what way the soil acts, and how far vegetation depends on the actual materials of which it is composed. If any of the constituent parts are wanting, they may usually be supplied at no very great distance, and it is chiefly such soils as do not suffer decomposition that are necessarily and hopelessly barren ; but these are so few, that they need hardly be the subject of consideration. Perhaps one of the most common examples of an ordi- nary barren soil is that in which the soil is composed of silex, either pure and in the form of compact rock, or is made up of loose grains of sand, mingled only with a cer- * Some plants, as the grasses, require a considerable quantity of silex for their proper growth and nourishment ; and this, which is chiefly present in the stalk, is supplied in the form of silicate of potash. But the grasses also require phosphate of magnesia, which is an invariable constituent of their seeds ; and thus the pre- sence of phosphorus, potash, silica, and magnesia in the soil is absolutely necessary for the proper growth and ripening of a crop of wheat. Other plants possess other salts and alkaline bases, and in different proportions, and all these different substances require to be presented to the roots of the vegetable in the most con- venient form for absorption. 488 AGRICULTURAL GEOLOGY. tain proportion of alumina and oxide of iron, not sufficient to admit of the ready growth of plants. Such soils as this are to be found on some parts of the coast of Flanders ; they occupy also the tops of some hills and mountains of igne- ous origin, and they certainly offer no prospect of return for labour bestowed upon them in such situations. But in the interior of a country where heath and furze once plant themselves and flourish, although there may be at first little prospect of success to the agriculturist, the case is by no means hopeless ; and the vicinity of clay might often be taken advantage of to bring these districts into profitable cultivation. The alumina and lime in such case may be supplied artificially, and the other inorganic consti- tuents may often be obtained from the decayed and de- composed plants which have grown upon the spot. It is unnecessary to say that sandy beds allow the moisture to traverse them very readily, and are soon heated, so that the crops grown upon them suffer greatly from drought. This must be to a certain extent unavoidable. Stiff clay, unmixed with a sufficient quantity of silica in the form of loose sand, is sometimes extremely difficult and troublesome to bring into cultivation. The chief want in this case to be supplied is that of lime ; for there is always abundance of silex, although not in the best or most conve- nient form.* The stiffest clayey beds, when dressed with * It is a fact not a little interesting, that sand thrown by the sea on the coast of Cornwall is very extensively employed in the interior of the country for agri- cultural purposes. Vast quantities of this sand (estimated at one hundred thousand tons) are annually taken from Padstow harbour to the interior ; and this cannot be considered more than one-fourth part of the whole quantity removed. Between five and six millions of cubic feet of sand are thus annually conveyed from the coast, and spread over the land in the interior as mineral manure. In this case, however, the sand is riot siliceous, but consists almost entirely of comminuted sea- shells, and thus affords the requisite supply of carbonate of lime to the clayey lands of the interior. De la Beche's Report, &c. p. 479. MINERAL COMPONENTS OF SOILS. 489 lime, are readily made to bear valuable crops ; but, as the clay is exceedingly retentive of water, and yields it back to the atmosphere with great difficulty and very slowly > it is often necessary that artificial drainage should accompany whatever other method may be adopted for the bringing such soils into cultivation. Limestone, when pure, or nearly pure, as in the state of chalk or crystalline limestone, is often a barren rock ; and this is especially the case when it is exposed on a hill-top, where the rain is unable to transport those argillaceous portions which have been washed from adjacent clayey beds. An admixture of clay, however, converts decomposed limestone or chalk into marl, and in this state it becomes an ad- mirable soil. Magnesia is a very common, and almost necessary, con- stituent of soils ; and it is worth while remarking here, that the lime and magnesia, as well as the potash and soda found in soils, are all of great importance, and form bases which, when mixed with oxygen, are in a condition to be absorbed by plants to whose growth they are essential. None of these earths however alone, nor indeed any two of them, even when associated with carbon, are sufficient to form a pro- ductive soil ; and, besides being mingled in the proper pro- portions, it is necessary also that the mixture should possess a proper texture, adjusted to the quantity of rain that is likely to fall ; for without this the air is not properly sup- plied to the root of the plant, and the process of oxidation, effected during the slow decomposition of this air, and upon which the growth of the plant seems to depend, does not commence, so that the plant is either parched for want of moisture, or stifled for want of air. As a general rule, it has been noticed that more rain falls on mountainous dis- tricts than in plains ; and this exactly answers to the usual 490 AGRICULTURAL GEOLOGY. position of clayey soils in plains and valleys, and a freer and more open soil on the high ground. With regard to the relative value of different geological formations in agriculture, it will be evident, from what has just been stated, that no general rules can be laid down ; and that, as it is rather the mineral and physical character than the geological age, the determination of which is im- portant, the Geologist can only bring his knowledge to bear in any given instance when he has informed himself of the actual structure of the district. In our own country, the older rocks are frequently barren, in consequence of the absence of limestone ; but where that is present, and there is a due admixture of silica, argil, and limestone, as in some of the Silurian districts, and some parts of the Old red sand- stone, a strong and excellent soil is obtained. The Old red sandstone, both in Herefordshire, and elsewhere where its texture is good, is often exceedingly productive. The soil which covers the strata of the carboniferous or newer Palseozoic period is rarely of great value for agricul- tural purposes, owing to the preponderance of crystalline limestone in a condition which resists decomposition, and the almost uniform absence of argillaceous beds, except in the upper part, and associated with the coal measures. In these latter beds, however, the presence of argil does not tend to render the land productive, so that the whole series of these rocks is poor and valueless so far as the surface is concerned. Fortunately their mineral treasures beneath the surface far more than make up for this deficiency. The culm measures of Devonshire Ho not form an exception to the general agricultural condition of the upper carboniferous beds in other parts of the British Islands. The Magnesian limestone, overlying the coal measures, and covered up by the beds of the New red sandstone, is SOILS OF DIFFERENT GEOLOGICAL FORMATIONS. 491 not uniformly valuable for cultivation ; but some of the dis- tricts where it preponderates are remarkable for being the. best and richest grazing districts in the north. The mag- nesian limestone, if burnt, and used on the soil, is, however, extremely injurious, remaining for a long time in the same state, and seriously checking all kinds of vegetation. The New red sandstone, although not so thick as many of the older beds, covers a very large tract of England, and is remarkable almost everywhere for its great fertility. It consists of sandstones and sands, for the most part of loose texture, and alternating with innumerable beds of marl ; and these are most abundant in the upper portion, which is not unfrequently characterised by a strong marly loam. Hence it arises that the latter, being the stiffest and most clayey bed, is usually employed as arable land ; while the remaining portions are admirably adapted for pasture, and are celebrated in some parts of the country for the excellence of the hay grown upon them. The Lias, with its associated marlstone, varies from a cold, wet, and extremely tenacious blue clay, to a strong and valuable clayey loam, and its value in an agricultural sense depends on the proportion of limestone and marl asso- ciated with it. In the upper part, where the sands of the inferior oolite rest upon it, they are sometimes turned in, and mixed with advantage ; but there is always in such case a want of drainage, and the soil remains cold. The principal part of this formation is in old pasture, and forms the dairy districts of Somerset, Warwick, Leicester, &c. The Oolites (including the Wealden) consist of so many alternations of calcareous beds with and and clay, that they offer almost every variety of soil, and are throughout capable of the highest cultivation. Where the limestone is too prominent (which is sometimes the case), the clays 492 AGRICULTURAL GEOLOGY. are generally at hand to correct the evil ; and the clays, if sometimes too stiff and tenacious, require only a thorough system of drainage to furnish the best and richest crops of wheat that can be grown in our island. The great Oolite is, perhaps, the bed least readily turned into cultivation, and this arises from the small quantity of carbon it retains upon its surface.* The Wealden beds, also, are apt to form into hard pasty masses, into which the roots of vegetables penetrate with difficulty. The beds of the Cretaceous group vary much in agricul- tural value : the lower beds, those of the lower greensand, are often exceedingly rich and capable of the highest culti- vation, and the upper chalk forms extensive downs, which are well known for their short sweet herbage, supporting large flocks of sheep. The lower beds of chalk are with- out flint, and are often mixed with alumina, which con- verts them into a rich and valuable marl ; while the soil at the junction of this marl with the upper greensand is a very productive loam, making an excellent corn land. The lower greensand, although in some parts of the country, as in Bedfordshire, exceedingly rich, occasionally supports only an imperfect, heathy vegetation, but it is not unlikely that careful cultivation, and the mixing of soils, may ultimately render this also productive. The Tertiary beds of England consist chiefly of the ar- * With regard to the capability of the Oolites for cultivation, 1 need only re- mind the reader who is acquainted with the middle of England, of the varied and rich woodland scenery in some parts of Oxfordshire, Northamptonshire and Gloucestershire, where the hilly character of the ground is derived from the suc- cessive escarpments of the Oolites. The views from the Cotswold hills, (the hard beds of which are themselves capable of the highest cultivation, when a moderate share of time and money is judiciously expended on them,) and the fine scenery to be enjoyed by any one who will cross the country in search of it, (for that is necessary,) will most richly repay any trouble that the exertion may cost ; and no one can have a correct idea of the physical features of the Oolites in the middle of England without thus journeying over the country in search of the picturesque. SOILS OP DIFFERENT GEOLOGICAL FORMATIONS. 493 gillaceous beds filling up the basins of London, Hampshire, and the Isle of Wight, together with the diluvium of Nor- folk and Suffolk and other districts in the east of England. The crag, although interesting in a geological point of view, covers but a small tract of country. The lower beds of the London clay, consisting of a plastic clay associated with sand and gravel, present every degree of fertility between the extremes of a poor and worthless soil, where the gravel prevails, and a wet, cold soil, where the clay is unmixed : where, however, the gravel and sand have sufficiently tempered the clay, and the land is free from springs, a rich productive loam is often met with. The London clay itself is for the most part tough and tenacious, but is much improved by an admixture of sand. The diluvial deposits under certain conditions, as in Nor- folk and Suffolk, are sometimes rendered exceedingly pro- ductive ; but in other districts they consist too entirely of fragments of flints, and hard siliceous and other rocks, to be brought into profitable cultivation. In the county of Norfolk, however, the worthless sandy and gravelly soil of this kind resting on chalk and chalk-marl has been so far improved in texture and quality by mixing, that the rich and valuable land of that county may almost be said to have been made by artificial management. It will be seen, therefore, that there is on the whole a uniformity of agricultural character affecting even the sand- stones, limestones, and clays of each geological period, and that, cateris paribus, the amount of fertility to be antici- pated from any particular rock may be to a certain extent decided by a knowledge of its geological position. Before concluding this chapter, I would add a few re- marks on a subject of considerable interest immediately bearing on what has been said : I mean, the determination 494 AGRICULTURAL GEOLOGY. of the value of land, and the advantage of an adequate knowledge of Geology in attaining this result. Where an estate is situated on several beds cropping out in succession, and of different agricultural value, a person ignorant of Geology would be greatly puzzled to determine the value of the estate ; and it would present appearances extremely different if the surveyor first walked across it in the direction of the dip, and afterwards on the strike. In order to obtain a true notion of the value, subdivisions of the property must be made, and the arranging these would be greatly facilitated by knowing the lines of out- crop of the different strata. But, besides enabling the land-agent to do this, and to identify the various soils, with the general productiveness of which in other places he should be acquainted, Geology would point out what land is in a forced, exhausted, or ordinary state of cultivation ; while from the mineral structure of the subjacent rock the composition of the soil may be inferred, and any substance detrimental or favourable to vegetation be detected. " A surveyor, therefore, should be acquainted with the nature and extent of the geological formations, especially those in the more immediate sphere of his duties ; and in acquiring, as well as applying this knowledge, he would be much aided by good geological maps. He should, also, make himself thoroughly acquainted with the relative pro- ductiveness of the soils on these formations ; and in valuing an estate, he should observe the texture of the soil and sub- soil, the dip and compactness of the strata, and the form of the surface of the land ; all these circumstances greatly affecting the value of landed property." * * " Whitley's Application of Geology to Agriculture," p. 143. I must again acknowledge my obligations to this book, which has greatly assisted me in the preparation of the present chapter. 495 CHAPTER XV. AGRICULTURAL GEOLOGY Continued. THE NATURAL AND ARTIFICIAL DRAINAGE OF LAND. IN describing the different kinds of soil and subsoil that are occasionally met with, I had occasion in the last chapter to allude to the subject of drainage ; but I intentionally reserved all explanation or consideration of the matter till it was introduced regularly before the reader, as a distinct branch of Agricultural Geology. The various methods of natural and artificial drainage of land, so far as they bear upon Geology, will be the subject of the present chapter. The drainage of an island or continent is effected, under ordinary circumstances, by means of a gradual and usually gentle inclination of the surface of the country towards the coast-line of the sea which bounds it. The rain which falls on the various parts being conducted by channels, or rush- ing down the hill-sides into brooks, is by them conveyed to the neighbouring rivers, and these, descending into and tra- versing the plains, at length reach the sea ; the rate of mo- tion of the waters in all these channels necessarily depend- ing on the amount of the fall, and the relation it bears to the distance traversed during the whole course of the stream from the high ground to the sea. Now there are two points in this statement which de- serve attention, namely, first, that the rate of motion, or the velocity of the current, has reference to the distance 496 ORIGIN OF FEN-LANDS. traversed, as well as the amount of fall ; and next, that after the water has been conducted to the foot of the hills, in which it is chiefly collected, it frequently has to traverse a large extent of country nearly horizontal, or in which the descent towards the sea is hardly appreciable. Both these points must be evident to every one who considers the sub- ject ; for the latter is simply a statement of fact, which may be verified by referring to almost any map ; and the former is equally clear ; for if a river has to traverse a cer- tain tract of country in a direct line to the sea, with a given amount of fall, then if the distance traversed is increased by means of the sinuosities of the channel through which the water is obliged to pass, the rate of motion must evi- dently be diminished. In those cases in which an extensive tract of nearly flat land (its elevation not being much above the level of high- water) is traversed by a number of streams, nearly stagnant for want of a sufficient fall to carry off the water, there is an evident tendency to form swampy and marsh land, and the slightest accident may at any time produce this result, and lay under water a whole district. Such is the condi- tion of the fen-lands in the East of England, and such also is in some measure the case with those parts of Holland near the Rhine, and with the land at the mouths of many other rivers in all parts of the world. The practicability of effectually draining and bringing into cultivation these lands is one of the subjects to be discussed in the present chapter. But there are other cases of a totally different kind, in which the long continuance of moisture on the soil is ex- ceedingly injurious, and prevents cultivation. Among the most remarkable of these must be ranked those numerous instances of peat- bog which are so common in Ireland, and CAUSE OF NATURAL DRAINAGE. 497 in many other countries, where the water is retained partly or entirely beneath a thick tough coating of vegetable soil, made up of the matted roots of plants. The drainage of bogs in this condition requires, as may be supposed, a pro- cess quite different from that which would succeed with fen-lands ; and most of the cases in which it is required to improve land by drainage will be found to refer either to the class just described, or to that of which the fens offer the best example. These two, in fact, include the different methods of surface drainage ; and, after explaining the circumstances under which one or the other of them may be pursued, I shall add a few words, in conclusion, with respect to an- other part of the subject, involving the consideration of the drainage of strata, and the means by which deep cuttings, tunnels, and other engineering works, are rendered secure. Before proceeding to the consideration of those contri- vances by which drainage can be artificially effected, it will be useful to see how Nature herself has arranged in ordinary cases, which are offered as it were for man's imitation, and which leave so little comparatively to be done by man in rendering the earth a fit receptacle for those plants and vegetables that are required for his sustenance and enjoyment. The very fact of stratification itself, and the manner in which the subsoil and the soil are derived by decomposi- tion from the underlying rock, afford a ready explanation of the well-drained condition of the soil in any district that is tolerably fertile. Drainage is indeed a natural result of the existence of alternating strata of different materials, some (as sandy beds) allowing water to penetrate them freely, others (as the clays) resisting its passage, and others again (as the limestones) admitting the water by numerous VOL. II. 2 K 498 SURFACE DRAINING. cracks and fissures into reservoirs and subterraneous caverns, but not absorbing it except near the place of contact, and remaining elsewhere dry and unchanged. All these different beds occurring at intervals, and being covered up by the subsoil, which rarely resists the passage of water through it, the surface-water, when in excess, penetrates into the subsoil, and is thence carried down till it reaches a permeable stratum, where it is absorbed and swallowed up, unless, indeed, as sometimes happens, this bed is already sufficiently loaded with water, and can no longer receive it. There are thus two very different condi- tions under which the natural soil of a district may be ren- dered infertile by the presence of stagnant water, and in like manner there are two ways in which drainage may be effected, the one of which is called surface and the other deep-draining. By the former is meant the carrying off the water by drains cut upon the surface, while the latter depends rather upon the geological condition of the underlying rock. It rarely happens that a large tract of land is so far in- jured by the presence of stagnant water as to become fen- land or swamp, except when the soil and subsoil, and even the subjacent rock, consist of tough stiff clays, spread over the country nearly at a dead level. Such is the case with the fen-lands of Cambridgeshire and Lincolnshire, where the Kimmeridge and Oxford clays are in contact, (the in- termediate calcareous bed being absent,) and are of great and unknown thickness. These beds, therefore, extending over a very considerable tract of country and being totally impervious to water, barely admit of complete natural drainage, because there is hardly sufficient fall to carry off the surplus water, which they obtain partly from the atmosphere, and partly from the numerous streams which FEN-LANDS OF CAMBRIDGESHIRE AND LINCOLNSHIRE. 499 come into them from the oolitic beds on the west and north, and from the chalk and greensands on the south and east. There are eight principal rivers traversing this district, and these empty themselves into the sea by three main trunks, (the Welland, the Nene, and the Ouze,) at Boston, in Lincolnshire ; Wisbeach, in the Isle of Ely ; and Lynn, in Norfolk ; all of them situated near that remarkable shal- low bay, called the Wash. There can be little doubt that the whole of the fen district has been at one time in the condition of the Wash, and that afterwards it was for a long period constantly subject to inundation from the sea, but during this time large portions of it were in all pro- bability permanently covered with sheets of water, some of which (as, for instance, the fresh-water lake called Whit- tlesea Mere) still remain. Even so lately as during the wars which followed the conquest of England by the Nor- mans, the Isle of Ely (a small outlier of the lower green- sand resting on the Kimmeridge clay) was literally an island and quite surrounded by water ; although after- wards, in the reign of Stephen, the neighbouring country is said to have been "one of the most fertile in England."* However this may be, it is probable that for several cen- turies after this time the district was subject to the incur- sions of the sea ; although, as the level of the country is slightly above that of high water, the rivers which traverse it were capable, under ordinary circumstances, of effecting a certain imperfect drainage. It was required, however, in order to render the soil permanently valuable, that some system should be devised for its complete drainage ; and the most obvious course would have been to scour out, widen, deepen, and straighten the rivers and the tributary streams, * Wells' History of the Drainage of the Bedford level, vol. i. p. 67. 2 K 2 500 FEN-LANDS OP CAMBRIDGESHIRE AND LINCOLNSHIRE. and embank their sides, and then to convey into these streams the waters that were retained in the intermediate tracts by a system of drains, out of which the water could be lifted by pumps worked by machinery, (wind-mills, steam-engines, &c.) This method was the obvious one under the circumstances, and would, no doubt, have proved perfectly successful, had not the undertaking been unfor- tunately commenced under the plans of a Dutch engineer, (a Colonel Vermuyden,) whose knowledge of draining was confined to the methods in use in Holland and Flanders, where the general level of the greater part of the land is below that of high water, and the sea requires to be kept out by locks and breast-gates, and a series of embankments on a stupendous scale. The mistake thus made in the commencement of the fen- drainage has never been completely set right ; for the sys- tem adopted, that of intersecting the district with a number of straight drains, without much reference to the natural outlets, has been so extensively acted on, as to render it almost impossible to expect that a good natural system could now be carried out. The artificial system at present adopted may be thus explained. Certain proprietors of a given tract of land agreeing together, the boundary of the district is set forth, and subdivision dykes are made for draining the estate of each owner. These ditches empty themselves into a main drain, (cut at the general expense of the owners,) which runs through the whole district, and is well embanked. This terminates at one end near a river, on the banks of which machinery is erected, (in many cases a steam-engine), by which the water is lifted and discharged into the river, whence it passes by the nearest course to the outfall, and so to the sea. The circuitous course taken by the rivers is PEAT-BOG. 501 avoided in some cases by stupendous cuttings, and the water is thus conducted as rapidly as possible, the sea being kept out by sluice-gates at high tides, and the gates being opened to allow of the outlet of the water when the height of the sea admits of it. The draining of extensive tracts of fen-land is a work of such magnitude, and of expense so enormous, that it ranks among the most important of engineering operations. But this is not the case with other kinds of drainage, which are sometimes confined to much smaller districts, and occasion- ally even to small portions of a single property. These latter also depend more immediately on local peculiarities of geological structure, and admit of many ingenious con- trivances, suggested by the nature of the underlying strata, and their order of arrangement. A few instances will best illustrate the nature of these contrivances. The existence of peat-bog, so remarkably abundant in Ireland that it is said to cover one-tenth of the whole sur- face of the country, is entirely owing to the presence and accumulation of vegetable matter, several of those plants which inhabit moist situations assisting in its formation. It occurs on the faces of declivities in mountainous regions, where there is much moisture, and attains also an enormous thickness in low grounds, where, however, it owes at least half its volume to the presence of water. The water in these cases is retained beneath the surface of the bog, which often shakes and yields under pressure ; and some- times, after a wet season, the bog will burst, owing to an excess of fluid raising it to an unusual height. In such cases, a stream of black, half-consolidated mud, pours out with greater or less velocity, and has occasionally been the cause of very serious and fatal accidents. It will be manifest that a district in which such a sub- 502 DRAINAGE OF BOGS. stance prevails is not very well adapted to become culti- vated land ; but it is interesting to find that, by taking advantage of geological structure, there may in some cases be a possibility of reclaiming bogs, and rendering them available for supplying the wants of man. DRAINAGE BOG DRAINED BY PIERCING THE UNDERLYING RETENTIVE BED. In the above diagram (a) represents a bog resting on an impermeable bed (5), which may be of stiff clay, and which in its turn rests on a porous, sandy, or gravelly bed (c). By piercing the bed (#), and sinking such a number of bore-holes or shafts as may be necessary, the uppermost bed may be drained through the clay, which, being after- wards turned up and mixed with the peat, will form an excellent loam for most purposes of agriculture. Another somewhat remarkable instance of drainage, effected naturally by means of the irregularities of an under surface of chalk, is quoted by Sir H. De la Beche,* and is represented below. The chalk is here covered, but not en- NATURAL DRAINAGE BY THE IRREGULARITIES OF THE UNDERLYING ROCK. tirely, by a bed of stiff clay, and over this is a soil composed partly of gravel and partly of clay. Those portions of the surface near the places where the chalk projects through the clay are well -drained and fertile, the chalk absorbing that portion of the water which sinks below the surface to * " How to Observe. Geology," p. 289. DRAINAGE BY FAULTS. 503 the bottom of the gravel. In other parts, removed from these peaks, the subsoil drainage is imperfect, and the soil is barren. Such a contrivance may sometimes be imitated artificially. I have already mentioned an instance in which a bog may be drained by piercing through a bed which is imper- meable into one below, which allows water to percolate through it. I now subjoin a section exhibiting a similar contrivance, where the object has been to drain a stiff clay which is not too thick, and which rests on a group of strata DRAINAGE A STIFF SOIL DRAINED BY SINKING INTO THE UNDERLYING BED OF GRAVEL OR SAND. amongst which there are sands. In the diagram, sinkings as at (#, 5) may often be attended with beneficial results, the drainage can certainly be effected by such means un- less, indeed, as in the former case with regard to the bog, the lower sand is already full of water. Even in this case, however, the water may sometimes be discharged at a natural or artificial cutting, laying open a lower portion of the sand as at (c). Besides the ordinary conditions of stratified rocks, the faults, or results of the disturbances of strata, may also occasionally assist the agriculturist in the drainage of land, for some of these faults are pervious to water, and act as main drains to large portions of country, while others, again, are filled with clay, and keep in the water on one side of the fault, preventing its passage to the other. In either case advantage may often be taken of the fault by any one possessed of an adequate knowledge of Geology. 504 ADVANTAGES OF DRAINAGE. As a fit conclusion to this part of the subject, in which I have considered drainage as connected with agriculture, I append, in a somewhat abridged form, some interesting re- marks offered by Mr. Johnson in his Lectures on Agricul- tural Chemistry (p. 440). The advantages of drainage to the agriculturist are nu- merous and manifest. In the first place, it carries away rapidly the superfluous moisture, moderates the natural dampness of the climate in a wet, boggy country, and is equivalent, therefore, not only to a change of soil, but also to a change of climate, both with reference to the growth of plants and the health of the population. Drainage produces, also, the effect of an actual deepen- ing of the soil, as it facilitates deep ploughing, and permits a greater absorption of useful moisture, and useful mineral salts, or organic matter, while it is also the means of noxi- ous mineral compounds, such as the salts of iron, being dif- fused equally and harmlessly through the soil, or carried away before they have time to form those ferruginous com- pounds which are injurious as an impervious subsoil. Drainage also alters the direction of the currents which occur in wet soils, the roots of plants obtaining their mois- ture from the rain which falls on the surface in drained lands, whereas in deep, swampy ground, their spongioles are only supplied with exhausted subsoil water.* Lastly, it is a necessary preparation to many other means of improvement which may be applied to land, and must in all cases be preliminary to every kind of build- ing and engineering work, as no foundation can be stable, * This is the more important, if, as Liebig supposes, the nitrogen required by plants is supplied in the form of ammonia by rain-water. At any rate it is cer- tain that the rain carries down in solution those nutritive substances that may exist near the surface of the soil, and these could not be supplied to the plant in any other way. DEEP DRAINING. 505 and no situation good, in which the water is allowed to remain and accumulate on a retentive soil. The process of deep draining differs from that of surface draining already described, and has for its object a some- what different result. It is also connected with the subject of road and canal-making, and requires to be understood and carefully attended to by the engineer, for without such attention a canal may be useless, after all the expense of construction has been incurred ; and a line of road may be so dangerous as seriously to interfere with the traffic upon it. The drainage of strata, one of the operations involved in the process now under consideration, necessarily requires an intimate knowledge not only of the geological structure of the particular district to be drained, but also of the general principles of Geological science ; and Mr. William Smith, who at the close of the last century had made himself much more accurately acquainted with the actual order of super- position of the Secondary strata in England than any per- son then living, was also one of the first to apply this know- ledge to important practical purposes. About the year 1800 his reputation for " draining on new principles " was thoroughly established in the West of England, and on the occasion of numerous landslips taking place near Bath, he was employed to prevent, if possible, a recurrence of this mischief, which he effected by tunnelling into the hill on which the land was slipping, and intercepting the springs, and then providing a direct and convenient channel, by which the water could be discharged. In the year 1811 Mr. Smith was again employed to report on a subject of practical science connected with the drainage of strata. About that time numerous canals were being cut in different parts of the West of England, 506 SUBTERRANEAN DRAINAGE. and these, crossing the oolitic hills, were found to be parti- cularly liable to accidents of leakage, being cut through open jointed, and sometimes cavernous rocks, alternating with water-tight clays. In the passage across the former rocks, and more especially when the summit level of the canal occurs in them, the water escapes almost as fast as it enters, and all the skill of the engineer in puddling, and making an artificial bed, is sometimes exerted in vain, and cannot prevent great and ruinous loss. But the existence of open joints and caverns is by no means the only, nor, in- deed, the greatest source of injury, for innumerable small faults or slides traverse the country and confuse the natural direction of the springs, rendering them short in their courses, and uncertain and temporary in their flow, weaken- ing by their irregular pressure every defence that may be opposed to them, and causing leaks, which let through a portion of the water contained in that level of the canal. The general remedy for all these evils was understood by Mr. Smith, and proposed by him for adoption. It is " the entire interception of all the springs which rise from a level above the canal and pass below it through natural fissures and cavities. This is a process requiring great skill and extensive experience ; some of the springs for instance which it is most important to intercept come not to the surface at all in the ground above the canal, but flowing naturally below the surface through shaken or faulty ground, or along masses of displaced rock which extend in long ribs from the brows down into the vale, emerge or attempt to emerge in the banks of the canal; these no ordinary surface- draining will reach, and none but a drain- ing engineer, well versed in the knowledge of strata, can successfully cope with such mysterious enemies. But Mr. Smith, confident in his great 'experience, not only proposed, DRAINAGE OF RAILWAY CUTTINGS. 507 by a general system of subterraneous excavation to inter- cept all these springs, and destroy their power to injure the canal, but further, to regulate and equalize their discharge, so as to render them a positive benefit. This he would have accomplished by penning up the water in particular natural areas, or pounds, which really exist between lines of fault in most districts, or between certain ridges of clay ( c horses,') which interrupt the continuity of the rock, and divide the subterranean water-fields into limited districts, separately manageable for the advantage of man by the skilful adaptation of science." * This account of the nature of the work required in sub- terranean drainage is so much to the purpose that I need add little further in illustration of the subject. The princi- ples involved must in most cases be nearly the same, and whether it is required to prevent a canal from leaking, or a deep cutting or tunnel from being drowned, or whether, finally, it is the object to prevent that washing away of a thin intermediate stratum, by the absence of which an up- per bed will be enabled to slide upon a lower one and pro- duce a landslip, the general nature of the contrivances to be adopted differs but little, although the particular method must in all cases be strictly adapted to the special condi- tions involved, and must vary in every district. It is only by a clear and accurate comprehension of the actual cause in each instance, that the draining engineer can hope to succeed, whether in combating an evil that already exists, or preventing an accident that is foreseen. Besides the application of the principles of draining on a large scale, it is often important in cuttings of moderate depth, when made in stiff clayey beds alternating with oc- casional sand, to provide against the danger of slips. This * Professor Phillips' Life of William Smith, p. 69. 508 WATSON'S PATENT DRAINAGE. can only be done by thoroughly and effectually draining the whole of the clay near the exposed surface. For this SECTION OP A RAILWAY CUTTING. WATSON'S PATENT DRAINAGE. purpose a method indicated in the above diagram has of late years been introduced, in which a number of perforated cast-iron draining-pipes are inserted into the clay sides of the cutting for about twenty or thirty feet, each pipe slant- ing towards its open end, so that the water which passes into it is immediately drained off. It is found by ex- perience that the holes for the pipes, being made by a boring machine which simply cuts away the material with- out hardening or polishing the natural substance of the clay, the water drains freely into them in wet weather ; and when the weather is dry they permit the clay around them to dry also, so that in this way a system of cracks and fissures communicating with one another is established in'the clay, by which the whole of it is drained thoroughly to 'a considerable distance from the surface of the cutting. The efficacy of this system has been proved in the trouble- some cutting in the London clay between the Camden Town and Euston Square stations of the Birmingham railroad, where the water was found to trickle from these pipes after they had been for some time inserted, although at first they remained perfectly dry. 509 CHAPTER XVI. AGRICULTURAL GEOLOGY Continued. THE PHENOMENA OF SPRINGS AND WELLS. ARTESIAN WELLS. IF, as we have found in the last chapter, an excess of water remaining undrained upon the earth's surface is high- ly injurious to that kind of vegetation which is useful to man, the absence of a proper and sufficient supply of mois- ture is no less a cause of infertility, so that a knowledge of the circumstances under which springs naturally rise out of the earth is of great value to the agriculturist, more espe- cially if hy such means the existence of springs, and of subterraneous reservoirs of water, can be predicated in any particular district. A knowledge of this kind is also quite as necessary to the engineer and the architect, as to the agriculturist, for it is not unfrequently the case that the selection of a site for building, or of a line of road or canal, may be greatly in- fluenced by the probability, or otherwise, of springs of water being tapped. The atmosphere is well known to be the main agent em- ployed by Nature in the distribution of moisture upon the earth, absorbing a considerable quantity of water in its pas- sage over the sea and afterwards depositing it in the form of rain, owing to changes which take place in its tempera- ture, and, probably, in its electrical condition. Of the quantity of rain, however, which falls upon the earth in a 510 NATURAL SUPPLY OF WATER. given spot, only a small proportion finds its way to the sea directly and immediately, by means of rivers ; and it has been calculated by M. Arago that this proportion in the valley of the Seine is not more than one-third. Of the rest, some portion is, no doubt, re-absorbed by the atmosphere, and some enters immediately into the composition of plants and animals ; but a large quantity remains, and this de- scends into the bowels of the earth by means of those strata which are permeable to water, and it is either retained in them until they are full, and then poured over their edges into the neighbouring country, to feed the nearest stream ; or is discharged in the form of perennial springs, where the containing stratum is exposed on a hill-side ; or, lastly, is accumulated in subterranean sheets and reservoirs, whence it is only discharged by some natural or artificial communica- tion being made to the surface at a lower level. Let us, however, trace a little more minutely the course of that portion of the rain-water which descends beneath the surface of the earth, and let us do this with reference to the order of arrangement of those various substances of which the superficial crust of the earth is made up. We shall in this way discover the rationale in each variety of circumstance under which the springs occur. It will be evident, on a little consideration, that as there are different circumstances under which springs of water rise through the superficial crust of the earth and make their appearance at the surface, these must, in all proba- bility, have reference to different conditions of the strata. It will, in fact, be found that this is strictly the case, and that the occurrence of springs is, in every instance, a phenomenon which it requires a thorough knowledge of Geology to illustrate and take advantage of. I will explain shortly the nature of these various kinds of NATURE OF LAND-SPRINGS. 511 springs, and the geological conditions necessary for their existence. ILLUSTRATION OF THE OCCURRENCE OF LAND-SPRINGS. 1. Land Springs. One of the most common cases in which springs of water make their appearance along a line of country, and generally on a hill side, is exhibited and explained by the above diagram, in which there are three strata represented ; the lower and upper of which are sup- posed to be impervious to water, while the middle one allows the water to permeate readily. The water, draining into this middle bed, is conducted along, until it reaches a spot, as at c, where it is laid open by the structure of the country, and where the water escapes into the valley, of which the diagram is a section. In this case the outcrop of the permeable stratum is readily distinguished after rain by the line of springs which accompanies it ; but these springs, and therefore the indications they offer of the bed, often disappear in dry weather. It happens also occasion- ally that the spring, although flowing, is not immediately exposed, but is covered up with gravel or vegetable soil or perhaps by an impermeable subsoil, but it may then be ob- tained by sinking a well, and may sometimes be found bub- bling up in a natural well, which it has formed for itself. It is not always, however, that these natural wells, or those which are artificially obtained by shallow sinkings into the subsoil or the gravel, are the result of any distant draining, and occasionally the water which falls in a dis- trict is collected into the hollows of the nearest retentive stratum, and may be obtained by simply sinking down a 512 LAND-SPRINGS. few feet to meet them. This is illustrated in the annexed diagram, where the hollows are supposed to be occupied by a loose gravel, and covered by a tough but non-retentive coating of soil and subsoil. The water that falls on the district sinks at different places into the gravel, and is there preserved from evaporation, and may be obtained readily, but is rarely to be depended on after a continuance of dry weather. The diagram in page 511, besides illustrating the nature of common springs at the outcrop of a bed, also explains an appearance which has sometimes been thought very unac- countable. An instance occurs in the valley of the Thames, near Richmond, where the river (which is there affected by the tides) has its channel cut in the London clay, part of which is a stiff clay, and part of it a loose gravelly sand (see diagram, B). It is found that many of the wells in the neighbourhood that are fed by the so-called land springs vary in height during the day, without reference to the weather, and are constantly rising and falling. This arises from the manner in which these wells are supplied, for they are sunk to the sandy bed which communicates with the river, and the water, therefore, rises and falls with the flux and reflux of the tide. A vast number of the irregularities to which the flowing of ordinary springs is subject may be explained in like manner by local circumstances, or by some peculiar geological conditions. 2. Regularly flowing springs of cold water, connected with, and arising from, faults. The class of springs pro- SPRINGS ON A LINE OP FAULT. 513 ILLUSTRATION OF THE PHENOMENA PBODUCING SPRINGS ON A LINE OF FAULT. duced by the existence of those simple displacements of strata, called " faults," includes a vast number of cases in many limestone districts, and more especially in those of the carboniferous period, which in England are usually the most disturbed. So numerous, indeed, are these cases, that, according to the observations of Mr. Hopkins in Derbyshire, every instance of a spring was accompanied by independent evidence of the existence of a fault, and in these districts the line of springs more frequently marks the fault than the regular basset of the stratum. The cause is simple, and will be at once understood by re- ferring to the above diagram, where the middle of the three beds is supposed to be permeable, and the other two reten- tive. The water stopped at the fault rises to its own level, and generally makes its way out at the surface ; but it is manifest that under certain circumstances it may again make its way into the permeable bed, by the fracture of which its course was changed ; and if so, it may ultimately come out at a hill side as an ordinary land spring. 3. Thermal and Mineral Springs. Springs of water containing mineral matter, either in mechanical suspension or in solution, are common in many parts of the world. It has been found in almost every instance of this kind (or, at least, whenever from its unvarying temperature the water appears to have come from such a depth as to be more or less independent of atmospheric changes), that the average, or constant temperature is above the average annual tem- perature of the place at which the spring comes to the surface. It is also the case that, with very few exceptions, VOL. II. 2 L 514 THERMAL AND MINERAL SPRINGS. no variations of external temperature manifest themselves in the thermal springs of a district, and that in all such exceptions the excess of heat is inconsiderable, except where volcanic operations, going on at the present day, have been the manifest causes to which the change must be re- ferred. Besides the mineral matter contained by thermal waters, it is not unusual for large quantities of gas to be constantly evolved from such springs ; carbonic acid gas being both the most frequent and the most abundant. With regard to the geological phenomena accompanying springs of this kind, they are extremely interesting, and the observations concerning them are already sufficiently nu- merous to enable us to state the general result. It is cer- tain that by far the greater number of them arise in the vicinity of some great subterranean disturbance either con- nected with volcanic action or with the elevation of a chain of mountains, or, lastly, with clefts and fissures caused by disruption. In illustration of this, it is only necessary to mention the remarkable districts of Matlock and Bath, in our own country, where thermal springs appear accompany- ing great natural fissures in the mountain limestone. This is also observable with regard to the hot-springs of Wies- baden and Ems, near the Taunus chain ; of Aix-la-Cha- pelle, near the Eifel ; of Carlsbad and Toeplitz, near the Mittelgebirge, in Saxony ; of Central France, in the ex- tinct volcanic district of Auvergne ; and of various places in the Alps, the Apennines, and the Pyrenees.* Among the most remarkable and the grandest pheno- mena of this kind must be ranked those magnificent fountains of boiling water, which are known to burst forth * I have not space here to dwell on the peculiarities of geological position of these and other celebrated localities of hot-springs in Europe. They are all con- tiguous to remarkable dislocations, to great lines of elevation, or to active volcanic BOILING SPRINGS OF ICELAND. 515 at irregular intervals in several parts of the volcanic plateau in the middle of Iceland ; and these, although they exhibit but little analogy with the ordinary phenomena of thermal springs, must not be passed by without notice, since the accounts that have been given by different visitors vary so considerably as to leave no doubt that the prevalence of volcanic action in the district is constantly effecting great changes. The best known of the Icelandic hot springs are called the Geysers, and they form a group of wells situated in a valley about a mile broad, the bottom of which is a marshy meadow through which several small brooks wind their way. On the south side of the valley the three snow-clad peaks of Hekla tower above the rocky wall which bounds the plain ; and on the north side is a hill, about three hundred feet high, separated by a narrow defile from the adjoining mountains. A little south of this elevation (which slopes gently towards the level ground) lie the far-famed fountains, and more than fifty of them can be counted within the space of a few acres. They are of two kinds ; the one filled with hot water as clear as crystal, the other giving vent to warm vapours, occasionally accompanied by a little muddy fluid; and these last are confined to the summit or acclivity of the hill, whilst the others are only found in the plain at its foot. The most remarkable of these singular fountains is some- times called ' the Geyser, 1 to the exclusion of the rest, and is situated on a mound of siliceous tufa, formed from its de- posits, about thirty feet high and two hundred feet in dia- meter. On its summit is the basin, sixty feet across, and six or seven feet deep, the bottom of which terminates in a pipe ten feet wide at the mouth, but gradually narrowing to seven or eight feet, in a perpendicular descent of nearly 2L2 516 FOUNTAINS OF THE GEYSERS. twelve fathoms. The interior both of the basin and the pipe is smoothed and polished by the constant friction of the hot water, which rises in small jets every two hours. Between the intervals of the jets the water only half fills the basin, and remains quite still, at a temperature of 154 Fah. ; but, at the depth of sixty feet, the temperature has been said to amount to 255 Fah. The great eruptions of this fountain seem to take place once in about twenty-four or thirty hours, but not with any regularity, the discharge being greatly affected by the erup- tions of the neighbouring volcano, and the periods having frequently undergone great change. In the account from which I chiefly quote,* the eruption is described as being preceded by a hollow rumbling sound, and a number of explosions, accompanied by a violent quivering motion in the ground. The author then states, that having been driven from the spot by this movement, he turned at a little distance, and beheld a thick pillar of vapour shooting like an arrow to the clouds, and surrounding a body of water, which rose with a fluctuating motion to the height of eighty or ninety feet, some portions of the fluid rising even above this, or streaming in arches from the cloud. Sometimes the steam divided, and exhibited the aqueous column shooting upwards in innumerable rays, spreading out at the top like a lofty pine, and descending in fine rain; at other times it closed in thicker darkness round the centre, veiling it from the eyes of the spectator. The eruption continued about ten minutes, when the water sank down into the pipe, and the whole was again in repose, the basin being completely empty, and the water far down in the pipe, and slowly ascending. In other in- * Krug von Nidda, Karsten's Archiv. ix. 247. See the account of Iceland, Greenland, and the Faro Islands, in the Edin. Cab. Lib. 1840, p. 59. EXPLANATION OF THE GEYSERS. 51 7 stances, clouds of steam have continued to escape long after the eruption of water has ceased, and the eruption has then been observed to close, as it began, with a loud explosion. It is a fact worthy of remark, that the numerous thermal springs grouped together in the valley of the Geysers ap- pear to be quite unconnected with one another, each having its own interval between the eruptions, and several of them sometimes playing at once ; while occasionally a consider- able period will elapse without any of them boiling up, or exhibiting any feature of activity. Several conjectures have been hazarded in explanation of these remarkable phenomena. Sir John Herschel has sug- gested that it would be sufficient to imagine a subterranean stream of water flowing through the pores and crevices of lava, and suddenly reaching a fissure in which the rock is intensely heated. Steam would then be formed instantane- ously, and, rushing up the fissure, it might force up the water with it to the surface, while at the same time part of the steam might drive back the water of the supply for a certain distance towards its source ; when, after a space of some minutes, the steam was all condensed, the water would return, and the phenomenon be repeated. THE GEYSERS OF ICELAND. Perhaps, however, a more probable method of explaining the action of the Geysers, and one perfectly consistent with what is known of the district, is that of which the above diagram will serve to give an idea. The water from the 518 INTERMITTENT SPRINGS. surface is supposed to drain gradually by numerous fissures in the lava, and through the loose scoriae, into a subterra- nean cavity, into which at the same time steam at a very high temperature also penetrates from below, by similar cracks in the heated rocks. For a certain time the steam is condensed into water, and the temperature of the water running into the cavity is raised, until at length the cavity becomes filled, the lower part with boiling-water, and the upper part with steam, under a very high pressure. As this pressure increases, the expansive force of the steam be- comes at length so great that the water is forced up the pipe, at first gradually, but soon with tremendous violence, and the eruption takes place ; the steam as it expands continuing to force up the water in the cavity, till it is completely emptied. As soon as this happens the steam also escapes, and the same thing goes on again. 4. Intermittent Springs. The class of springs that next comes under our notice consists of those which, from a cer- tain alternation of flux and reflux, not dependant upon the quantity of rain falling in the district or on the tides, have been called " intermittent." These do not appear subject to any general law affecting the period of their recurrence ; nor are they, like the boiling springs of Iceland just de- scribed, referrible to any cause in which heat is called into action. They admit, however, of a very ready and suffi- cient explanation, and one strictly corresponding with the geological conditions of the rocks from which they flow. The fundamental principle involved in the explanation of these springs is a simple and well-known hydrostatical law, exemplified in the common siphon,* and the application of it to intermittent springs is sufficiently evident. * A siphon (see diagram) is a bent tube, having one leg longer than the other. When this tube is filled with any liquid, and the shorter end is immersed in a INTERMITTENT SPRINGS. 519 In the annexed diagram the vessel (a) communicates by a tube (c) with the siphon tube (b) ; and it is manifest that when the water in (a) rises above the level of the top of (b) it will begin to flow over, and escape as at (d). But as soon as this is the case the tube (b) begins to act as a siphon, and draws off all the water in (#), so that if a con- stant supply is poured into (), but at a rate slower than the rate of the discharge at (d), there will be an intermit- tent discharge, the interval depending on the relation of the rate of filling to that of emptying. INTERMITTENT SPRINGS. Now let us apply this explanation to the case of a sub- terranean cavity in a limestone rock, slowly fed by drain- vessel containing liquid of the same kind, the weight of the column in the longer leg will cause the liquid to begin to run out, and it will continue running till the vessel is emptied. This arises from the pressure of the air on the exposed surface of fluid forcing it up through the tube to prevent a vacuum, which would otherwise be formed at the highest point ; and the extreme limit of length at which the siphon will act is therefore determined by the height of a column of the fluid equal to the pressure of the atmosphere (fifteen pounds on the square inch). This limit in the case of water is something more than thirty feet. 520 ARTESIAN WELLS. age from the cracks and fissures of the rock above, but communicating at a distant point with the surface by a bent or siphon tube. It can hardly be necessary to do more than point out the strict analogy between this case and the one just assumed ; and there can be no doubt, from what we know of the structure of limestone rocks, that such a condition as that represented in the diagram is, to say the least, very possible. Besides this case of an intermittent spring, in which the spring flows occasionally and is then dry for a cer- tain period, it is yet more common to find springs which constantly flow, but are sometimes greatly increased with- out any apparent cause for the increase in the quantity of rain fallen in the district. It is more than probable that in such cases there is a siphon tube communicating with a large reservoir, which has another outlet insufficient to drain it completely. The periodical increase is then the result of the siphon, and the ordinary supply is independent of it. 5. Artesian Wells. Artesian wells are so called from the French province of " Artois," where, so far back as at the beginning of the twelfth century it was the custom to ob- tain springs of water artificially, by piercing the soil to a certain depth in places where no indication of springs exist- ed at the surface. When, therefore, in other districts water is obtained by boring, and when, more especially, the water thus reached rises considerably in the well, the term Artesian is applied, and serves to distinguish these springs from those which flow naturally, or in which there is no tendency to rise above the level of the basin or reservoir in which the water is contained. The hydrostatic principle involved in the existence of Artesian wells is quite as simple as that according to which the siphon empties a vessel of water. It is simply this, that ARTESIAN WELLS. 521 water, when forced to pursue any direction, or travel to any distance in confined tubes, will always tend to rise to the level of the open water with which it communicates, and, whenever the means are afforded, will always so rise. In the annexed diagram, if (a) is a vessel provided with a ILLUSTRATION OF THE PRINCIPLE OF ARTESIAN SPRINGS. bent tube (, c), then if water is poured into the vessel, the pressure at (b) (c) will be equal to the weight of a column of water reaching from those points respectively to the level of the water in (a) ; and if, therefore, a tube is inserted at (c), the water will rise in (c) to that level. This will be the case, also, if a tube is inserted at (<#); the dimensions of the tubes (c) (d), and their actual length, being in- different. It will be understood that this is a known law of fluids, and may be proved by experiment. Let us now see the nature of the application of this law in one or two simple cases. In the diagram given below the mechanical conditions are precisely the same as in the former one, and the only differ- 1LLUSTRATION OF NATURAL ARTESIAN FOUNTAIN. ence is, that the reservoir is supposed to be contained in a cavity in some stratum, and the tube (&, c) is continued, 522 ARTESIAN WELLS. and is open at (e). At this point there will be a natural fountain, the water rising as it would if an aperture were made at the end of the tube in the former diagram. It must be perfectly clear, that if a communication is made at any point between (d) and (e) the water will rise to the surface, and even above it, and an Artesian spring will be there produced. Again, let us take the case represented in the annexed sketch, that, namely, of a basin-shaped depression in reten- tive rocks, partly filled with retentive beds, which, however, admit the passage of water to their lower part. This case ILLUSTRATION OF AN ARTESIAN SPRING IN A BASIN-SHAPED DEPRESSION. is, in fact, that of the London Basin, and of a large number of other basins of the Tertiary period. There will be little difficulty in understanding the action of those wells which are here dug through the retentive clays to the loose sands of the lower beds. The water accumulates at the bottom in extensive reservoirs, which, when not only they but the channels which supply them are full, exert a pressure on the overlying beds proportioned to the height of the column of water, measured from the level of the water in these channels to that of the contact of the clay-beds with the underlying chalk, where the lower sandy beds come to the surface and the water therefore enters. When therefore the overlying beds are pierced, the water immediately rushes up, either towards the surface or above it accord- ing as the circumstances may admit. This will be clear on referring to the diagram illustrating the principle of these springs ; for if the pressure on every part of the surface at ARTESIAN WELLS. 523 (a) were not equal to that on every part of (c), the water in the two tubes could not remain at rest ; and we know by experiment that a column of water at (c), however small, will balance and keep at rest a column at (a), however large. * It is evident, then, that although there are several circumstances and several geological conditions by taking advantage of which Artesian wells may be obtained, the principle is the same in all, and the modifications are to be decided on by the Geologist rather than the Engineer. It is for this reason that I have given so minute an account of the principle involved. With regard to the fact that in limestones, and such like rocks, there do exist great natural caverns, and that even in clayey beds there are alternating bands of sand and gravel capable of receiving a considerable quantity of water, communicating with the surface and sometimes passing down to immense depths, there can be no doubt whatever ; and it is equally certain that in some of them, at any rate, the sheets of water are of very considerable extent. ~f* This is known not only by the examination of * This has been sometimes called the hydrostatic paradox, and a very inge- nious application has been made of it in what is called * Bramah's press ' by means of which great pressure is produced over a large surface by a proportional pressure upon the surface of another column, the area of the horizontal section of which is exceedingly small. f* As instances may be quoted, 1st. the rock of Torghal in Norway, which is pierced from end to end (more than three thousand feet) by a rectilineal opening one hundred and fifty feet high. 2nd. The celebrated cavern of Adels- berg, in Carniola, which receives the waters of a river, contains a large lake, and has been traced for a distance of at least six miles, but is probably much more extensive. 3rd. The fountain of Vaucluse, which issues from subterraneous rocks, and pours fourth a volume of upwards of thirteen thousand cubic feet per minute, even under ordinary circumstances, and this increases sometimes to forty thousand cubic feet. There is also proof that many of these caverns and sub- terraneous rivers communicate with the surface, for fish, and even seeds, are occa- sionally conveyed into them with the water. 524 ARTESIAN WELLS. such rocks of the kind as are exposed at the surface, and by the appearances they there present, but also from the occasional cavities discovered in boring for Artesian wells, and also in sinking deep shafts in mining districts.* As being perhaps one of the most interesting of these, and proving that springs obtained from great depths are sometimes dependant on atmospheric supplies and obtain- ed by means of the peculiar geological structure of the country, I may mention the case of a fountain at Nis- mes, in the south of France, the supply from which, even in times of great drought, amounts to one hundred and forty-five gallons of water per minute ; but it is found that, when it rains heavily at a distance of about six or seven miles from the fountain, in a north-westerly direc- tion, an increase takes place suddenly in the supply, so that it then sometimes pours forth as much as one thou- sand gallons per minute, the temperature of the water supplied undergoing no change. It is clear in this case that the spring must be fed from a distance, and by * As an example of this may be quoted the remarkable head of water met with in the sinkings of the deep coal-pit at Monk Weannouth, Durham (see p. 339). It is also recorded, that in a boring undertaken some years ago, at Paris, after the work had proceeded at its usual slow rate for a long time, the auger suddenly es- caped from the workmen's hands, and they saw it fall upwards of twenty feet, when its top was caught by the transverse handle, at a place where the orifice was smaller. The rapid ascent of the water soon explained the cause of this accident. During some sinkings near Dieppe as many as seven great sheets of water have been tapped ; and under the city of Tours there appears to be distinct evidence of the existence of a subterraneous river, for on one occasion the fountain in the Place de la Cathedrale (sunk to three hundred and thirty-five feet), brought up portions of vegetable matter, among which were branches of thorns an inch or two long, the stems, roots and seeds of marsh plants and different kinds of grain ; and fresh-water and even land shells were also found mingled with these remains, which from their condition appeared to have been several months under water. OCCASIONAL FAILURE OF ARTESIAN WELLS. 525 means of long channels, which allow the water to flow rapidly through them. The rapidity of communication also is so great, that these channels must in all probability be open. But if the explanation of the phenomena of Artesian wells here given is the right one, there ought to be a degree of uncertainty as to the result of sinkings carried on even in the same district ; for the underground re- servoirs cannot always communicate with one another ; and, though in many instances they are of very great size, they must occasionally be small and partial. Numerous examples are on record of this irregularity, and some of them are very remarkable. Amongst them may be mentioned an instance at Blingel, in the valley of Ternoise, in which, of three bores undertaken at the same time, and not very far asunder, one supplied abundance of water, rising out of the earth with a jet d'eau, while the other two have not produced a drop of water at the same depth. In another spot also, a bore having pierced to the depth of one hundred feet, thirty of which was through limestone rock, a beautiful limpid stream of water was ob- tained, rising in a jet d'eau ; but, in a garden contiguous, the same rock has been penetrated to a depth of one hun- dred feet without success. The cases of failure are, as might be anticipated, com- paratively rare when the sinkings are intended to reach a permeable bed known to rest on one which is imper- meable, and to be overlaid by another also impermeable ; although even these are not always successful, especially when commenced without a previous consideration of the geological condition and probable thickness of the rock to be pierced. The sinkings in the London Clay how- ever seldom fail to produce a supply of some kind, although 526 ARTESIAN WELL OF GRENELLE. the depth that has to be penetrated for this purpose varies very considerably.* Perhaps the most remarkable instance on record of a successful sinking for water, commenced at the instance of scientific men, who, from their knowledge of the Geology of the district, were confident of ultimate success, was the Ar- tesian well lately completed at Grenelle, one of the suburbs of Paris. This work was commenced in 1834, under the auspices of the French Government, and it was calculated that, after passing through the tertiary beds and the chalk, the upper greensand would be reached, at a depth probably of twelve or fifteen hundred feet. Up to the time, however, of the undertaking of this work, no successful Artesian sinking had reached to a greater depth than about one thousand feet. The operation was commenced with an auger of unusual Dimensions, (being about a foot in diameter,) and the borings shewed successively the alluvial soil and subsoil, and the tertiary sands, gravels, clays, and lignite, &c., until the chalk itself was reached. The work was then carried on regularly through the hard upper chalk down to the lower chalk with green grains, the dimensions of the auger being reduced at five hundred feet to a nine-inch, at eleven hun- dred to a seven-and-a-half inch, and at thirteen hundred feet to a six-inch aperture. * At Sheerness, water is obtained in the lower part of the London clay at about three hundred feet, and then rises above the level of the ground. At Ful- ham, the London clay does not appear to contain a supply, but sinkings of about seventy feet in the underlying chalk have been attended with success. At Ham- mersmith, sinkings to three hundred and sixty feet, and at Chiswick, in the gar- dens of the Horticultural Society, at three hundred and thirty feet, abundant sup- plies have been obtained ; but in the Duke of Northumberland's grounds above Chiswick no water was obtained at the junction of the London clay and the chalk, nor until the latter rock had been penetrated to a great depth. At six hundred and twenty feet, however, a reservoir was tapped which delivered the water not only at the surface, but about four, feet above it. ARTESIAN WELL OF GRENELLE. 527 When the calculated depth of one thousand five hundred feet had been reached, and as yet no result appeared, the Government began to be disheartened, and public patience to be exhausted. Still, upon the urgent representations of M. Arago, the sinking was proceeded with, until at length, at the depth of one thousand eight hundred feet, (five hun- dred and forty-eight French metres,) the rushing up of a vast body of water offered the most satisfactory proof of the correctness of the principles on which the work was commenced. The first rush of the water when the stratum was pierced was very violent, an immense volume of water, mixed with sand and mud, and of a very high temperature, rising many feet above the surface. The force, indeed, with which the rise took place was so great, that con- siderable injury was done to the rods ; and it was some time before the shaft was sufficiently cleared for the full discharge to issue without interruption. The spring, how- ever, has been for some time in action ; and the volume of water being measured a few months ago, was found to have lost nothing of its force or quantity. About half a million of gallons are now supplied in the twenty-four hours, and the water has been perfectly limpid since tubes were inserted in the aperture. 432 3 4 SECTION ILLUSTRATING THE ARTESIAN WELL OF GRENELLE. 1. Tertiary beds of the Paris basin. 3. Upper greensand. 2. Cnalk. 4. Underlying retentive beds The above diagram illustrates the Geological condition of the strata in the neighbourhood of Paris with reference to this well. 528 PERMANENCY OF ARTESIAN SPRINGS. In all deep Artesian wells the temperature of the water, as it comes to the surface, is warmer than the average annual temperature at the surface, and is also much less affected by atmospheric changes. This corre- sponds with similar observations that have been made in mines, and, indeed, wherever man has been enabled to penetrate to great depths beneath the crust of the earth. In the unusually deep well at Grenelle, just described, it will not therefore excite astonishment that the heat of the water is very considerable. It appears also to be constant, and reaches 82 of Fahrenheit."" There is no reason to doubt the permanency of the sup- ply of water obtained from Artesian wells. As an instance, perhaps the oldest on record, I may mention a spring of this kind at Lillers, in the north of France, which has con- tinued to give the same supply of water, projected to the same height above the surface, for upwards of seven hundred years, the quantity of water daily poured out at the sur- face not having been known to vary during that long period. I have now brought to a conclusion my remarks on that department of Agricultural Geology which has refer- ence to the obtaining a supply of water at the earth's surface ; and it will have been observed perhaps by the reader, that the phenomena described and explained, how- ever remarkable they may at first appear, are all strictly in accordance with the ordinary operations of Nature, and * Advantage has sometimes been taken of the temperature of water from deep springs, and conservatories have been warmed, and even cress-plots cultivated by such means. It is stated that a salad ground at Erfurt, in which this method is adopted of communicating a regular and high temperature, yields a profit of not less than 12,000?. per annum to the proprietor. Fish-ponds have been sometimes improved by such warm springs being passed through them. DISTRIBUTION OF RAIN-WATER. 529 immediately result from the action of the fundamental laws imposed upon matter. But the constant modifications of the action of these laws, owing to the peculiar method of arrangement of the materials which compose the exterior crust of the earth, is another subject which required notice ; and it has there- fore been my object in the preceding pages to communicate a knowledge of the method of arrangement upon which the results alluded to depend, since by the possession of such knowledge the practical man is able to apply the science of Geology in the ordinary operations of his profession. All the phenomena observed in the study of the Na- tural Sciences are thus found to form links in the great chain of events ; all of them may be traced to the operation of a few simple, but universal laws ; and all work together in harmony to the perfect carrying out of the whole system. Although, however, indications of this harmony and unity of design in Nature are very often to be traced, perhaps there are not many departments of practical science in which they are exhibited more beautifully, or in a form better adapted for simple illustration, than that which is now under consideration. By a succession of contrivances not difficult to follow, we find that a portion of the water, which at one time forms part of the great ocean, and there holds in solution certain salts, is as it were distilled, and at the same time absorbed, during the passage of a current of air over it. Held in solution in this way, the water taken up becomes for a time an integral part of the atmosphere, and no doubt assists in producing those constant changes in its electrical state, on which so much of its usefulness in many ways depends. Carrying with it this supply of moisture, the current of air having passed over the sea, VOL. II. 2 M 530 DISTRIBUTION OF RAIN-WATER. reaches at length the dry land, where it is exposed to the action of many causes, both mechanical and chemical, until at length, owing to other changes thus produced, it becomes incapable of longer retaining the same quantity of moisture in solution, but is still able to convey it along mechanically as vapour, in which state it becomes visible, and forms what we call a cloud. In this manner the watery vapour continues to float over extensive tracts of land, or remains suspended in mid air, until at length the atmosphere is unable any longer to sustain its load ; the particles of vapour, aided also in this no doubt by electricity, then collect together into drops, and sink to the earth in the form of rain. Of the rain thus deposited upon the earth's surface a large proportion falls on mountain sides, (to which clouds are readily attracted,) and thence runs down in rills to join larger streams, which at length become rivers, and so this portion is either returned once more to the ocean or is reabsorbed by the atmosphere. Another part, also very large, falls on the thirsty soil, and becomes immediately one of the means of sustaining vegetable life ; and this part, undergoing chemical change, does not reappear in the form of water. But there is a third portion, which has other duties no less important to perform. A considerable quantity of the rain that falls sinks gradually or immediately into the earth, and owing to that arrangement of the rocks and stones and clays which we have been discussing, it is re- ceived into the permeable strata and internal reservoirs of the earth, as into a well-contrived magazine, and is there retained for a time, until at length it is given out gradu- ally in gentle streams which help to fertilise the earth, or are poured forth to supply the wants of man, when, by DISTRIBUTION OF RAIN-WATER. 531 the exercise of his ingenuity, he is able to profit by the admirable resources of Nature. The internal structure of the earth is thus made avail- able in a manner which could not readily have been anticipated, but it only requires a little consideration to perceive how exceedingly necessary to the fertility of conti- nents or other extensive tracts of land is this peculiar arrangement of the strata, by means of which the rain that falls sinks into the earth on the high ground and is returned to the surface in the plains. It may be that before these conditions were fulfilled the surface of our globe, although well adapted for the exist- ence of the lower animals, was not a fit habitation for man. The subjoined vignette was intended to form a tail-piece to Chapter XII. It represents a view of the Island of Portland, whence is derived the excellent building stone of the upper Oolites. VIEW OF PORTLAND ISLAND. 532 CHAPTER XVII. GENERAL CONCLUSION. NATURE OF PHYSICAL GEOLOGY. RECAPITULATION OF THE MAIN RESULTS OF GEOLOGICAL IN- VESTIGATIONS. THE nature of Geology : an account, that is, of the materials of which the earth's crust is made up; of the order in which those materials are arranged; of the changes in the original arrangement produced hy subsequent me- chanical violence ; of the organic bodies found associated with the inorganic materials ; and, lastly, of the practical benefit that is to be derived from knowing something of these facts : all this has now been stated in as simple and clear a manner as my ability and knowledge of the subject have permitted. It has been my object throughout the present work to set before the reader, in their proper light, these various matters ; and I have carefully avoided intro- ducing such disputed points as were likely to create con- fusion, or require that he should afterwards have to unlearn anything that is here taught. But although the subjects of discussion have been hither- to thus limited, it is not right that I should conclude with- out informing the geological student that there is such a science as Physical Geology, and that many of those per- sons to whose investigations the most important discoveries in Descriptive Geology are due, have also exercised them- selves in endeavouring to reduce to a system the observa- tions that have been made, and discover, if possible, the GEOLOGICAL THEORY. 533 nature and mode of operation of the laws according to which the earth has, after countless ages, assumed its pre- sent condition. But the theories of Geology have not yet been thoroughly confirmed by experiment ; nor can this be a matter of surprise when we consider how recent is the date of many of those observations, without including an expla- nation of which no one should venture to propound a theo- retical speculation. It has- seemed, therefore, to me, more prudent to avoid all allusion to such theories, than to men- tion them only to point out their imperfections, and thus perhaps add to the difficulties with which the subject is surrounded. But it should be clearly understood how far, at present, hypotheses professing to account for geological phenomena must be looked upon as Theories, and how far they may be safely admitted as real explanations ; and this is a subject on which I have already offered some remarks, but which also claims a certain degree of attention here. Sir John Herschel has observed, " The first thing that a philosophical mind considers, when any new phenomenon presents itself, is its explanation, or reference to an im- mediate producing cause. If that cannot be ascertained, the next thing is to generalise the phenomenon, and include it, with others analogous to it, in the expression of some law, in the hope that its consideration, in a more advanced state of knowledge, may lead to the discovery of an ade- quate proximate cause." * In this way, " laws of the first degree of generality," as such may be called, are obtained from the consideration of individual facts ; and in precisely the same way " Theories result from a consideration of these laws, and of the proximate causes brought into view in the previous process, regarded altogether as constituting * Herschel's Discourse on the Study of Natural Philosophy, p. 144. 534 GENERALISATIONS OF GEOLOGY. a new set of phenomena, the creatures of reason rather than of sense, and each representing, under general lan- guage, innumerable particular facts." * I have endeavour- ed throughout the present work to confine myself to the explanation of phenomena, and the elucidation of laws of the first degree of generality ; those of greater generality, the theories of Geology properly so called, not being per- fectly elaborated, and the analysis of phenomena, the im- mediate object of such theories, not having been yet fully effected. But I must once more repeat, and would press forcibly on the mind of the reader, the important and evident truth, that although the theory is not perfect, the observations, and even the generalisations up to a certain point are, not- withstanding, sound and unquestionable. It is according to the very nature of inductive reasoning and it is the method by which, of all others, the mind advances most surely and most satisfactorily to a conclusion, when, as has been the case in the progress of Geology of late years, observations are multiplied, the explanations of them tested by experiment, and the first processes of generalisa- tion thus established. But it will necessarily happen in framing inductions, or in other words, in obtaining these laws, that the mind of man, affected much more strongly by certain classes of phenomena than by others, lays hold, as it were, of these, and is inclined to carry out any explanation of them that may seem satisfactory, and apply it to other phenomena with which it has really nothing to do. This has been the case in the infancy of all sciences, and amongst the rest in Geology, and its result, the promulgation of so-called theories from the determination of a single law of gene- * Hcrschel, ante cit. p. 190. RESULTS OF GEOLOGICAL INVESTIGATION. 535 ralisation, has thrown into discredit all generalisations whatever. Now, that this too ready assumption of theory is unreasonable and mischievous, few, perhaps, would be found to deny; but it has been so frequently repeated, that the very name of ' Geological theory' has almost be- come a bye-word to express wild and foolish hypothesis. This alone might have been a sufficient reason for putting out of the question all mention of hypotheses on the pre- sent occasion ; but I also felt that the science would be more readily understood when expressed as a narrative of facts. The main points on which I have principally dwelt may be now very shortly recapitulated. In the first place, I have introduced the subject by an allusion to some striking instances of changes now in progress affecting the physical features of various parts of the earth's crust, and the rela- tion that exists between such causes and the actual condi- tion of the surface of the globe. I have then described in general terms the nature of the rocks afterwards to be considered, and the organic remains found imbedded in them ; and with regard to these introductory chapters, I would have the reader chiefly fix his attention upon the fact that a certain order of arrangement of rocks actually exists in Nature ; and that, with regard to organic remains, particular groups of species of fossils are to a certain extent characteristic of formations. In the chapters on the Descriptive Greology of fossilifer- ous stratified rocks, the different geological formations have been passed successively under notice ; and I have endea- voured throughout to illustrate the great truth that all these various formations were deposited under water, which sometimes appears to have existed as an extensive ocean, sometimes as a lake, and sometimes as a river or estuary ; 536 RESULTS OF GEOLOGICAL INVESTIGATION. and that there has been a degree of regularity, order, and succession, strikingly indicative of a uniform system, per- fectly adapted to all varieties of circumstance that could occur. The general result of these chapters may be thus ex- pressed : ' That the greater portion of the earth's crust, so far as it is at present known, consists of a numerous series of strata overlying one another in regular order, and most of them containing abundantly the remains of or- ganised beings ; and that these remains indicate the former existence upon the earth of animals extremely different from those which are its present inhabitants.' It also ap- pears that there have been numerous successive creations of species of plants and animals, often similar to those which had before existed, sometimes quite dissimilar, but never absolutely identical. In prosecuting the subject of Descriptive Geology, and considering that part of the science which relates to crys- talline and unstratified rocks, I have next proceeded to de- scribe the nature of those rocks, such as granite and basalt, which exhibit distinct marks of igneous origin ; and their influence both in greatly altering sedimentary strata, and in disturbing and displacing them, as if by mechanical vio- lence. In this part I have shewn that besides those strata which were regularly deposited, and are fossil iferous, there are others of a different kind, but also of mechanical origin ; and others, again, which shew no mark of stratification. It has also appeared that the circumstances under which these latter occur prove that some relation exists between their presence and the marks of mechanical violence affect- ing the regular strata ; and, lastly, that these causes of dis- turbance have acted very frequently, and during the whole period of the deposition of the aqueous rocks. PRACTICAL GEOLOGY. 537 Having completed this review of Descriptive Geology, I have in the remainder of the work confined myself to giving an account of the various practical benefits which may be derived by a due acquaintance with the fundamental truths of Geology ; and I cannot but feel that some explanation is due for the manner in which I have ventured to bring this part of the subject before the reader, as well as for the imperfections and inaccuracies that may be traced in the matter itself. I am neither an Engineer nor an Architect ; neither an Agriculturist nor a Miner ; nor do I lay claim to any of that minute knowledge of detail which can entitle me to be called a 'practical man' on any of the practical pursuits in which such persons are chiefly engaged. But I have endeavoured to make myself acquainted with these pursuits so far as they relate to the science which has chiefly occupied my time and thoughts ; and, perhaps, the labour bestowed in this way, and in a careful investigation of the influence of science on art, is not altogether unproductive of good ; for, although the scientific man who so employs himself has not the experience of the professional man, he also escapes many of the prejudices of a class ; and he has, beyond all doubt, a much greater facility in attaining those comprehensive views, without which the nature of the true relations of the different sciences with one another, and the bearing of them all on the arts of life, cannot be fully understood- But whatever view may be taken of this matter one thing is quite certain, namely, that, in order to arrive at useful practical results by means of Geology or any other science, clear and definite conceptions of the fundamental truths of the science, and a knowledge of its principles, are essen- tially and absolutely necessary. Without these, general information and a knowledge of facts may indeed be ac- 538 LANGUAGE OF SCRIPTURE quired, and there may be an appearance of familiarity with the subject ; but there cannot possibly exist that kind of knowledge which is calculated to become the basis of sound and useful conclusions. I would here close this chapter, and take my leave of the reader, were it not that I might seem in that case to make too light of a difficulty which is still felt by many well-meaning persons, with regard to the apparent contra- diction offered by some of the results of geological research to the account given in the Holy Scriptures of the creation of the world. I am far from undervaluing the importance of any diffi- culty of this kind ; but I would venture to remark on the real danger that must arise to the foundations of our faith, if the conclusions arrived at from the consideration of a large group of observations all tending to the same re- sult, should be set aside by any authority consisting of a mere dictum. The Book of Nature, laid open by the Su- preme Being for the study of his intelligent creatures, can only be understood by a careful and minute investigation into the phenomena of Nature ; but the immediate deduc- tions from the study of those phenomena are not less the truth, nor have they less claim to be admitted as unques- tionable than the direct injunctions contained in the written volume of inspiration. But I refrain from giving the opi- nion I have formed on this subject in my own words, and prefer concluding in the language of one whose truly philo- sophic and religious mind was well adapted to clear up a difficulty, such as that now under consideration, by means of which an undue attention to a form of expression has interfered with the reception of scientific truths. 4< The language of Scripture on natural objects is as WITH REFERENCE TO GEOLOGY. 539 strictly philosophical as that of the Newtonian system, perhaps more so ; for it is not only equally true, but it is universal among mankind, and unchangeable. And what other language would have been consistent with the Divine wisdom ? The inspired writers must have borrowed their terminology either from the crude and mistaken philosophy of their own times, and so have sanctified and perpetuated falsehood, unintelligible meantime to all but one in ten thousand ; or they must have anticipated the terminology of the true system without any revelation of the system itself, and so have become unintelligible to all men ; or, lastly, they must have revealed the system itself, and thus have left nothing for the exercise, development, or reward of the human understanding, instead of teaching that moral knowledge, and enforcing those social and civic virtues, out of which the arts and sciences will spring up in due time, and of their own accord."* I know of no explanation more satisfactory than this of the apparent want of con- gruity that exists between the simple record of the earth's creation in the first chapter of Genesis, and the conclusions arrived at by the study of Geology concerning the ancient condition of the earth, during the long period of its exist- ence previous to the placing on it, as its chief inhabitants, a race of rational and accountable beings. * Coleridge's Literary Remains, vol. i. p. 325. GENERAL INDEX. Those fossils of which the names are here printed in Italics are figured at the pages referred to. VOL. PAGE Abandonment of mines, import- ance of preserving records in such cases ii. 427 Aberdeenshire, floods of . i. 10 granite of . ii. 480 Accidents in coal mines . ii. 366 from slips of strata on a road . ii. 440 Acotyledonous plants . . i. 250 Acrita, subdivisions of . i. 69 Acrogens . . . . i. 259 Acrolepis, account of . . i. 506 Actinocrinites SQ-dactyltis . i. 271 Adelsberg, cavern of . . ii. 523 Adit-level . . . . ii. 288 Advantages of Geology in Engi- neering . . . . ii. 441 JEschna munsteri . . . i. 395 Africa, gravel of . . ii. 127 South, Silurian rocks of i. 120 After-damp in coal mines . ii. 342 Agassiz, Prof., his theory of gla- ciers . . . ii. 132 his classification offish i. 181 Agricultural Geology . . ii. 484 Aix in Provence, fresh-water basin of . . . . ii. 31 Alabama, Tertiary beds of . ii. 108 Alabaster of Derbyshire and Italy ii. 406 Alkaline bases of soils . . ii. 487 Alluvium, account of . . ii. 1 1 7 VOL. PAGE Almaden, quicksilver mines of ii. 265 Alps, French, mining districts of ii. 265 Lias of . . i. 319 Oolitic beds of . . i. 378 Cretaceous slates of . ii. 414 Alston Moor, its lead mines . ii. 263 position of workable veins in . ii. 254 Altai mountains, their metallic produce . . . . ii. 267 Alum, composition of . ii. 407 shale, at Whitby i. 316,ii. 408 works . . . ii. 407 Alum Bay, rocks of . . ii. 1 3 Alveolina oblonga . . ii. 63 Alveolus of Belemnite . . i. 332 Amalgam, native . . ii. 322 Amalgamation of silver, in South America . ii. 318 in Saxony . ii. 320 Amazons River, quantity of mat- ter brought down by it . i. 8 America, Silurian rocks of . i. 120 absence of Oolites in i. 382 (North) Carboniferous de- posits in . . i. 226 Cretaceous rocks of . i. 467 Tertiary Geology of ii. 105 gravel of . . ii. 127 mines of . ii. 270 (South) Cretaceous rocks of i. 469 mines of . . ii. 268 542 GENERAL INDEX. VOL. PAGE American coal, probably not all of the Palaeozoic period . ii. 329 American coal, worked in quar- ries ii. 363 American Devonian rocks . i. 173 Volcanoes . . i. 15 Ammonite, description of . i. 327 Ammonites colubratus . . i. 320 elizahetlice . i. 363 heterophyllus . i. 327 (Ceratites) nodosus i. 296 semi-canaliculatus i. 398 Amphitherium, account of . i. 419 Ampullaria acuminata . . ii. 25 Amygdaloid . . . ii. 184 Analysis of soils . . ii. 486 Ancaster, Oolitic building stone ii. 464 Ancillaria subulata . . ii. 10 Anglesea, minerals of . . ii. 262 Anoplotherium, account of . ii. 81 Antagonist forces, action of . i. 14 Anticlinal axis, meaning of . i. 35 Antimony . . . . ii. 323 Antrim, basaltic rocks on the coast of ii. 212 Apennine limestone . . i. 464 Apiocrinites rotundus . . i. 391 Appearance of coal districts . ii. 334 Aptychus . . . . i. 398 Aqueous and igneous forces, their joint action ii. 220 Aqueous theory of the deposition of metallic ores . . . ii. 274 Arago, M., on the Artesian well of Crenelle, Paris . . ii. 527 Araucaria, or Norfolk Island Pine, account of . i. 257 ArcktBoniscus brodei . . i. 434 Architecture, application of Geo- logy to . . . ii. 450 Ardennes slate . . i. 117, 168 Ardwick limestone . i. 208,212 Argentiferous lead ores . . ii. 310 Argile de Dives . . i. 373 Argillaceous limestone, value of as a building-stone . . ii. 455 VOL. PAGE Argyleshire, slate quarries of ii. 413 Arrangement, general plan of . i. 85 Arsenic . . . ii. 323 Artesian wells, principle of . ii. 520 different kinds of ii. 521 occasional failure ii. 525 at Crenelle, Paris ii. 526 permanency of the supply from ii. 528 Articulata, subdivisions of . i. 68 Artificial drainage of the fens ii. 500 Artois, province of, origin of Ar- tesian wells ii. 520 Asaphus caudatus . . i. 130 Ascension Island, recent limestone of ; . ii. 137 Ashburnham, Wealden beds of i. 423 Asia, Tertiary Geology of . ii. 87 Fossils of . ii. 98 (Minor) Cretaceous beds of i. 463 extinct Volcanoes of ii. 211 volcanic phenomena, effects of . ii. 89 Aspidorhynchus, description of i. 403 Association, British, representation concerning railway sections ii. 448 Asteria u. s. . ii. 66 Astr&a tvebsteri . . . ii. 58 Atmosphere, use of, in distributing moisture . . . ii. 509, 529 Atrypa affinis . . . i. 134 Aughriss Head, view of . ii. 188 Augite . . . ii. 178 Auriferous sands . . ii. 281, 321 Aurillac, fresh-water beds of ii. 30 Aust-cliff fish-bed . . i. 314 Australia, caverns of . . ii. 137 Auvergne, fresh- water basin of ii. 30 volcanic district . ii. 210 Avicula socialis . . i. 296 Axis, anticlinal . . . i. 35 Axmouth, lower Lias of . i. 315 Aylesbury, Vale of, Wealden beds . i. 427 Aymestry limestone . . i. 109 GENERAL INDEX. 543 B. Bacillariae . Baculites faujasi Badger fossil Bala limestone . VOL. PAGE . ii. 61 i. 484 . ii. 145 i. 97 Balahulish, state quarries of . ii. 412 Balruddery, grey sand-stone of i. 154 Baltic provinces of Russia, Silu- rian rocks of . . . i. 1 1 8 Banca, tin stream works of ii. 281 Banz, section of Lias at . i. 318 Barnack rag, an excellent building- stone . . . . ii. 463 Barnard Castle, Durham, condi- tion of ii. 473 Barren soils, nature of . . ii. 487 Bas Boulonnois, fossil wood of i. 368 Wealden beds i. 428 Basalt, characters of . . ii. 214 experiment upon . ii. 205 igneous origin of . ii. 204 overlying masses of . ii. 215 Basaltic columns, Fingal's Cave ii. 202 dykes ^ . . . ii. 216 Basilosaurus, see Zeuglodon. Basins, Artesian wells in . ii. 522 Bassetting edge of strata . i. 33 Bath, hot springs of . . ii. 514 Oolite . i. 359, ii. 460 Abbey church of, its condi- tion . . . ii. 461 Bavaria, alluvial plain of . ii. 38 Bawtry, Roche Abbey quarries, near . . . . ii. 466 Beaver, gigantic fossil species of ii. 86 Bedfordshire, Lower Greensand ii. 492 Belemnties, account of the genus i. 331, 399 ovalis . . i. 332 restored outline . i. 399 Belgian coal-field, oblique basins i. 221 Belgium, Cretaceous rocks of . i. 461 Devonian rocks of i. 169 Lias in south of . i. 317 Silurian rocks of . i. 117 VOL. PAGE Bell-Rock lighthouse, force of ma- rine currents shewn there i. 13 Bellerophon tangentialis . i. 275 Bensham seam, account of ii. 336 accident in Walls- end colliery ii. 374 accident in Jarrow colliery . ii. 375 Berwyn mountains . . i. 97 Beryx, description of . . i. 486 Beverley Minster, condition of the stone . . . . ii. 468 Bifrontia laudinensis . . ii. 25 Big bone lick, Kentucky . ii. 130 Bilston, iron ore from . . ii. 390 Bimana, account of . . i. 60 Birds, definition of . . i. 65 fossil, of the Chalk . i. 490 of the Paris basin and London clay . ii. 79 eggs of . . ii. 79 footmarks of . i. 311 gigantic species found in New Zealand . i. 312, ii. 164 Bismuth . . . . ii. 323 Black-band of iron ore in Scot- land . . . . ii. 392 Blackdown Hills, Geology of i. 454 Black-gang chine . . . i. 453 Black Sea, Geology of the bor- ders . . . . ii. 89 Blangy, Calcaire de i. 374 Blast-furnace, account of ii. 310, 394 section of . ii. 395 Blasting in mines . . ii. 298 result of, with different rocks . . . ii. 300 Blende (Black-jack) . . ii. 311 Blingel, unsuccessful attempts in Coring for water at . . ii. 525 Blowers or jets of gas in coal- mines . . . ii. 372 Boards or passages in coal-mines ii. 345 Bognor rocks, London clay of ii. 13 Bohemia, Silurian rocks of . i. 1 1 7 Boiling fountains of Iceland ii. 514 544 GENERAL INDEX. VOL. PAGE Bolsover, Magnesian limestone quarries of . . ii. 466 Bopyrus, its resemblance to Tri- lobites . . . . i. 129 Bordeaux, Tertiary beds of ii. 34 Boring for coal, method pursued ii. 337 Boring, cost of ... ii. 337 Boulders, account of . . ii. 115 Botany, subservient to Geology i. 2 classification of . . i. 249 of extinct plants . i. 247 Bovey coal, workings for . ii. 410 Bow and Arrow castle, Portland Island, condition of the stone ii. 460 Bowerbank, Mr., his investigation of chalk flints . i. 473 his account of fossil fruits of the London clay . ii. 54 Box Hill, quarries of . ii. 461 Brachiopoda, account of i. 67, 131 groups of extinct species . i. 134 of Devonian rocks i. 176 of Carboniferous rocks i. 272 of the Muschelkalk i. 300 of the Lias . i. 326 of the Oolites . i. 396 of the Cretaceou s rock s i. 482 Bracklesham Bay, Tertiary beds of .... ii. 14 Bradford clay, account of . i. 360 Brard's method of determining the disintegration of stones . ii. 458 Brattice, meaning of . ii. 338, 348 Braun-kohl (see Brown coal), workings for . . . ii. 409 Brazilian mines, account of ii. 268 Breakwaters, harbours, &c. ii. 446 Brick, why used as a building ma- terial . ii. 452 Bridlington, Crag deposits of ii. ] 9 fossil sponges at i. 477 Bridport, Oolite of . . i. 361 Bridport, fossils in chalk of i. 458 VOL. PAGE Brienz, Lake of . . . i. 470 Brine springs, proportion of salt in .... ii. 404 Bristol coal-field . . . i. 206 British Islands, produce of coal- fields in ii. 326 Brittany, Silurian rocks of i. 119 mining district of ii. 264 Brodie, Rev. P. B., account of in- sects discovered by him in the weald . . . . i. 435 Brodie, Rev. P. B., his account of the gravel near Cambridge ii. 116 Brodsworth, quarries of . ii. 467 Brontes flabettifer . . . i. 176 Brora, Oolites of . . . i. 369 lignite of . . ii. 410 Brown clay of Cambridgeshire, &c. . . . ii. 116, 122 Brown coal of Nassau ii. 327, 411 Rhine valley .ii. 47 Switzerland ii. 410 Brussels, Tertiary basin of . ii. 29 Buccinum arculatum . . i. 177 Itevigatum . . ii. 43 mutabile . . ii. 43 stromboides . . ii. 25 Biickeburg, Wealden beds of i. 429 Buddie, Mr., his account of the discovery of the Davy- lamp . . . ii. 367 his improved method of working coal . ii. 345 his testimony with regard to coal-mining records ii. 431 Buddling, a method of preparing tin ores . . . ii. 306 Bufonites . . . . i. 404 Building-materials, selection of, ii. 451 stones, rate of decomposi- tion ii. 458, 477 general conclusions concerning . ii. 478 Bullo, cylindracea . . ii. 18 Bumastus . . . . i. 129 Bundelkund, gravel of . ii. 134 GENERAL INDEX. 545 VOL. PAGK Bundelkund, Lias of . . i. 319 Bunter sandstein . . i. 294 Burdie-house limestone . i. 215 Burr-stone, or buhr-stone . ii. 108 C. Caen Oolite . . . . i. 371 Calamine . . . ii. 311 Catamites suckowi . . i. 253 Calamopora, distribution of . i. 126 Calcaire a polypiers . . i. 373 grossier . . . ii. 24 siliceux . . ii. 26 Calceola sandalma . . i. 177 Calcination of iron ores . ii. 394 Calne, coral rag of . . i. 364 Calp .... i. 216 Calvados, Oolites in the Depart- ment of i. 371 Calverley, Tunbridge Wells, build- ing-stone of ... ii. 476 Calymene blumenbachi . i. 123 Cambrian series, meaning of i. 95 rocks . . . i. 97 Cambridge, buildings of ii. 463, 475 Cambridgeshire, greensand of i. 454 gravel . . ii. 116 and Lincolnshire, fen districts of . - . . ii. 498 Canal, selection of a line for a ii. 444 correction of leakage . ii. 506 Cancellaria ii. 35 Caradoc sandstone . . i. 103 Carangopsis, account of . . ii. 73 Carbon, necessary for plants ii. 483, 487 Carboniferous system in England i. 199 sandstones . ii. 471 Carburetted hydrogen gas in coal- mines . . . . ii. 341 Carcharias, account of . ii. 75 Cardinia (Pachyodon) listeri . i. 320 Cardita . . . . ii. 35 Cardium aviculare . . ii. 25 lunulatum . . i. 397 VOL. II. VOL. PAGE Cardona,. salt deposit at . ii. 400 Carnivora, account of . i. 6 1 their abundance among fossil bones . . . i. 81 Carpathians, Cretaceous rocks of the ....... i. 464 CaryophyUia, account of . i. 390 annularis . . i. 365 centralis . . i. 475 Caspian Sea, Geology of the bor- ders of the . . . ii. 90 Cassidaria carinala . . ii. 25 Casts of organic bodies found fossil .... i. 52 Catalonia, volcanic district of . ii. 211 Catenipora escharoides . i. 127 Caturus, description of . . i. 403 Caubul, Geology of . . ii. 91 Caucasus, Oolites of the . i. 380 Caulopteris primceva . . i. 255 Caunter or contra lodes . . ii. 256 Cavern bear . . . ii. 141 hyaena . . . ii. 142 Caverns, origin of . . ii. 1 35 filling up of . ii. 136 natural, in limestone rocks ii. 523 Central France, mining district ii. 265 extinct volcanic dis- trict of . . . . ii. 210 CepMlaspis lyelli . . i. 187 Cephalonia, Tertiary beds of ii. 41 Cephalopoda, account of . i. 67, 137 of Older Palaeozoic rocks . . i. 141 Middle Palaeozoic rocks . i. 178 Newer Palaeozoic rocks . . i. 276 Triassic system i. 300 Lias . . i. 326 Oolites. . * i. 398 Chalk . . i. 483 Ceratites (Ammonites) nodosus i. 296 Cerithium., account of . . ii. 26 j, tricarinatum . ii. 25 2 N 546 GENERAL INDEX. VOL. PAGE Cetacea, account of . . i. 64 Cetiosaurus, account of . i. 407 Chsetodonts, family of . . ii. 71 Chalk formation . . i. 455 foreign range of . . i. 459 red ... i. 457 lower, used as building- stone . . . . ii. 455 Chama lamellosa . . ii. 125 Changes affecting the older rocks i. 144 produced in rocks by heat ... . . i. 28 Charlesworth, Mr., his determina- tion of the age of the crag ii. 16 Charnwood forest, Granite of ii. 182 slates of ii. 414 Cheltenham, Lias of . . i. 315 Chemical action of the atmosphere on building-stones . . ii. 478 Chemical action of the soil . ii. 486 Chemistry, subservient to Geology i. 1 Chepstow, quarries of Old red sandstone near . . . ii. 470 Chert, an admirable road mate- terial . . . . ii. 445 Cheshire and Worcestershire, salt mines of . . . . ii. 398 Chili, elevation of the coast of, by an earthquake . . i. 17 mining district of . . ii. 269 Chilmark, siliceous limestone of ii. 464 China-clay of Cornwall . . ii. 416 Chiracanthus, account of . i. 192 Chirolepis, account of . . i. 193 Chirotherium i. 308 Chiswick, Artesian well at . ii. 526 Chlorite schist . . . ii. 194 Chloritic slates of Cumberland i. 96 Choanites, account of . . i. 476 Choke-damp (carbonic acid gas) in coal-mines . . . ii. 372 Chromium ii. 323 Cidaris, account of . . i. 479 clavigera . . i. 471 coronata . . . i. 393 Cinnabar . ii. 321 VOL. PAGE Circassia, Geology of . . i. 463 Cirrhopoda, account of . i. 68 Cirrus tabulatus . . . i. 275 Classification, its importance in natural history i. 56 outline of the method adopted . i. 57 difficulties of . i. 58 of rocks, table of i. 92 of igneous rocks ii. 217 of Tertiary strata ii. 1 Clathraria lyetti . . i. 432 Clay-slate . . . . ii. 194 Clay-soils, management of . ii. 488 Claystone . . . . ii. 185 Cleavage of minerals . ii. 177 of slate rocks i. 38, ii. 197 and joints . . i. 38 Cligga Head, soil of . . ii. 484 Clinometer, account of . i. 32 Clunch used for building . ii. 455 Clyde, Geology of the valley of ii. 20 Clymenia, account of . . i. 178 inaequistriata . i. 179 Coal, its vegetable origin i. 246, ii. 326 probable limitation to the beds of the Palaeozoic period in Europe . . . ii. 327 of Virginia not Palaeozoic ii. 329 its probable duration in Eng- land . . . . ii. 364 its appearance on the out- crop, ii. 331 Coal and iron, their value in Eng- land . . . . ii. 325 Coal district, physical features of ii. 334 Coal-field, Newcastle i. 213, ii. 336 Lancashire . i. 211 Yorkshire and Derby- shire . . . i. 210 Staffordshire . i. 206 method of working thick beds in . ii. 348 Coal-field, Bristol . . i. 206 South Welsh i. 203, ii. 365 thick beds of, i. 205 GENERAL INDEX. 547 VOL. PAGE Coal-field, South Minister . i. 217 Leinster . . i. 217 Scotch . . i. 214 useful intersection of, by dykes and faults . . ii. 330 Coal-grit, its value as a building- stone . . . . ii. 474 Coal-measures, an unproductive soil ii. 490 Coal-mining records, importance of . . . ii. 431 nature of . ii. 432 Cobalt ii. 323 Coccosteus, scale of . . i. 191 jaw and teeth of '. i. 192 Cockfield-fell-dyke . . ii. 216 Coffee, fossil . . . ii. 56 Coleridge, his view of the lan- guage of Scripture with respect to science . . . ii. 538 Colley-Weston slate . . ii. 415 Colour of soils influenced by the under-lying rock . . ii. 485 Comatula of the Solnhofen slate i. 392 its resemblance when . young to a Pentacrinite . i. 324 Compact, meaning of the term in mineralogy . . . ii. 177 Component parts of soils . ii. 482 Conchifera, account of . i. 67 Concretions of Magnesian lime- stone . . . . i. 234 Conformable and unconformable stratification . . . i. 32 Conglomerates of the Old red sand- stone of Scotland . . i. 152 Conglomerates, quartzose . i. 149 Coniferous plants . . i. 259 wood, of the Lias . i. 321 Coniston Water-Head, limestone of i. 112 Connecticut, fossil footmarks of birdsinthe New red sandstone i. 307 Constantinople, Silurian rocks near . . . . i. 119 Contour lines on maps . ii. 238 VOL. PAGE Contra or counter lodes . . ii. 256 Conularia, account of . . i. 137 Conus diversiformis . . ii. 25 Coombe Down, quarries of ii. 461 Copper ores, preparation of . ii. 304 quantity raised in Cornwall . . ii. 305 pyrites (bisulphuret) ii. 303 sulphuret of . . ii. 303 slate . i. 242 Coprolites i. 348 Coral rag . . . . i. 364 Coralline crag . . . ii. 17 Corals of the Silurian rocks . i. 126 Devonian rocks . i. 175 Carboniferous system i. 267 Oolites . . . i, 389 Tertiary period . ii. 58 Corbis pectunculus . ii. 25 Cornbrash . . . . i. 361 Cornish mineral deposits . ii. 262 granite, supply of . ii. 479 Cornstone . . . i. 148 Cormdites, account of . . i. 127 serpularius . i. 145 Cornwall, mineral veins of ii. 246, 254 mining laws of . ii. 426 granite of . . ii. 182 Costeaning . . . . ii. 286 Cotentin, basin of . . ii. 31 Cotswold Hills, scenery of . ii. 492 Counter or contra lodes . ii. 256 Crag, divisions of the . . ii. 1 6 coralline . . . ii. 17 red . . . . ii. 17 mammaliferous, or Nor- wich . . . . ii. 18 Craigleith quarries, Edinburgh, sandstone of . . . ii. 471 Crassatella tumida . . ii. 25 Creep in coal-mines . ii. 344 Creseisforbesi . . . i. 136 spinigera . . i. 136 Cretaceous rocks of Britain . i. 447 building-stone of ii. 455 2 N 2 548 GENERAL INDEX. VOL. PAGE Cretaceous rocks, agricultural value of ii. 492 Crimea, Cretaceous beds of . i. 463 Tertiary beds of . ii. 50 Crinoideae, description of . i. 269 Crioceratites, u. s. . i. 363 Crisiellaria osnabrugensis . ii. 63 Croagh Patrick, view of . ii. 260 Crocodilians of London clay . ii. 78 Cross courses . . ii. 250, 257, 293 Cross cuts . . . . ii. 293 Crossing a current of air in a coal- pit . . . . . ii. 349 Crummock Water, view of . i. 162 Crustaceans of the Palaeozoic pe- riod i. 128 Crustaceans of the Old red sand- stone . i. 176 of. the Oolites . i. 394 of the Isle of Sheppey ii. 67 Cryptogamous plants . . i. 250 Crystalline structure . . ii. 177 and unstratified rocks ii. 168 carbonate of lime ii. 455 structure of building- stone, the best . . ii. 478 Crystallography, science of ii. 173 importance of in Geology . i. 41 Cucullaea elongata . . i. 320 Cucumites variaUlis . . ii. 54 Culm measures, a point of depar- ture for the Devonian system i. 157 Culm measures of Devonshire i. 201 an un- productive soil . . . ii. 490 Cumberland slates i. 96, ii. 195, 414 mining district of ii. 263 Cumbrian series of rocks . i. 95 Cupanoides inflatus . . ii. 54 Curf-bed, a variety of Portland stone , . . . ii. 457 Cushion-star (OpUura) . i. 392 Cutch, Oolites of . i. 381 Tertiary Geology of ii. 92 Cuttings and embankments ii. 439 VOL. PAGE Cuvier, his account of the diffi- culty of determining ex- tinct species . i. 55 his classification of the animal kingdom . i. 57 his account of the mam- malia of the Paris basin . ii. 80 Cyathophyllum, account of . i. 175 basaltiforme . i. 267 Cycadeae, account of . . i. 384 Cycadites ... . i. 387 ii. 25 . ii. 18 ii. 25 , i. 141 Cyprcea avellana Cyrena depressa Cyrthoceratite D. Danube, course of the . ii. 38 Dapedius, account of i. 336 palitum . . i. 334 Dartmoor, stanniferous granite of ii. 253 Darwin's, Mr., observations on slaty cleavage . . . i. 39 Davy lamp . ii. 368 Dax and Bordeaux, Tertiary beds of . . . . . ii. 34 Dean, Forest of, iron mines ii. 392 Deccan, Tertiary Geology of the ii. 96 Decomposition of building-stones, cause of . ..... ii. 477 Decomposition of building-stones determined by Brard's process ii. 458 Decomposition of subjacent rocks the origin of soils . . ii. 484 Dee, river, effects of, in a flood, i. 1 Deep draining . . . ii. 505 De la Beche, Sir H. T., his me- thod of proceeding in the Ord- nance Geological Survey . ii. 239 De la Beche's, Sir H. T., observa- tions on building materials ii. 453 Delabole, slates of . . ii. 412 Delhi, gravel of . . . ii. 134 Deltas, origin of . . i. 6 GENERAL INDEX. 549 VOL. PAGE Denbigh flagstone . . i. 98 Denmark, Cretaceous rocks of L 461 Dentalium striatum . . ii. 10 Denudation . . . . i. 37 valley of . . i. 37 Depth, great, of strata of which we have certain knowledge i. 29 Depth of shafts in coal-mines ii. 339 of soil, what dependant on ii. 486 Derbyshire coal-field . . i. 210 mineral veins in limestone ii. 253 mining district of . ii. 263 Alabaster of . . ii. 406 mining regulations of . ii. 426 Descriptive Geology, nature of i. 85 Devonian system explained . i. 156 marbles . . i. 175 rocks, foreign . i. 163 argillaceous build- ing-stone of . . ii. 455 DiaUage- . . . . ii. 185 Diamond mines of Golcondah ii. 97 Dicotyledonous plants . i. 250 Dieppe, quantity of water found in sinking a shaft . . ii. 524 Digitigrade Garni vora . . i. 62 Dillenburg fossiliferous slate of i. 116 Diluvial deposits, agricultural cha- racter of . . . . ii. 493 Diluvium, meaning of . ii. 116 Dinas Bran . . . . i. 33 Dinornis, account of . ii. 165 Dinosaurians . . . i. 408 Dinotherium, account of . ii. 84 Dip, definition of . . . i. 31 taking the . . i. 31 Diplopterus . . . . i. 194 Dipterus . . . . i. 194 Direction of productive mineral veins in Cornwall . . ii. 256 Direction of cross courses . ii. 257 Dirt bed, Isle of Portland . i. 367 Disaster (Spatangus) carinatus i. 393 Distribution of coal, limited ii. 328 mineral veins ii. 261 VOL. PAGE Distribution of rain-water . ii. 529 Disturbing force, its effect in producing various appearances observable in stratified rocks i. 30 Disturbing force, its effect on hard strata . . . . i. 36 Disturbing force, effect on beds of various degrees of hardness i. 34 Disturbing force, effect in coal- fields . . . . ii. 329 Dives, argile de . . . i. 373 Divining rod, use of the . ii. 287 Divisional planes or joints . i. 38 Dodo (Didus ineptus) . i. 70 Dolcoath mines, depth of . ii. 293 Dolomite . . . . i. 233 Dome-shaped elevation of strata i. 34 Don, river, effects of, during aflood i. 10 Doncaster, quarries of Magnesian limestone, near . . ii. 467 Donetz river, Oolitic rocks of i. 380 D'Orbigny, his researches on the Geology of South America ii. 110 Doulting in Wiltshire, limestone of ii. 462 Downton-on-the-rock . i. 109 Drainage, different kinds of . ii. 495 surface . . ii. 497 by irregularities of a sub- jacent rock . . ii. 502 of fen land . . ii. 498 of peat bog . . ii. 502 advantage of, to a soil ii. 504 importance of, in build- ing . . . ii. 451 subsoil, value of . ii. 484 of railroad cuttings . ii. 508 of mines in Cornwall ii. 291 Draining pipes, Watson's patent ii. 508 Drift, diluvial, of the Cumberland mountains . . . ii. 121 Drift, or water-course in mines ii. 340 Droitwich, brine-springs of . ii. 400 Dubois, M., his investigations con- cerning the Cretaceous rocks of the Caucasus , i. 463 550 GENERAL INDEX. VOL. PAGE Dudley coal-field, workings in ii. 360 limestone and shale i. 107 Dumb furnace, account of ii. 352 Dumbleton hill, marlstone of i. 315 Dundee, building-stone shipped from . . . . ii. 470 Dundry, Oolites of . . i. 361 Dunnet Head . . . i. 153 Dunstable, building-stone near ii. 455 Duration of coal in England . ii. 364 Durham and Northumberland mi- ning district . . ii. 263 Durham coal-field, faults in . ii. 330 coal-grit, used in build- ing . . . ii. 472 Durham, coast of, fragment of Magnesian limestone i. 244 cathedral, condition of the stone . . ii. 473 Dyke, meaning of the term . i. 37 Dykes, basaltic . . . ii. 216 E. Earthquake, elevation of land by i, 17 East Huel Crofty copper mine, workings of . . . ii. 279 Eccleston Abbey, condition of the stone . . . . ii. 473 Echini, structure of . . i. 393 Echinodermata, account of . i. 68 fossil Tertiary ii. 66 Economic Geology, Museum of ii. 242 Edentata, account of i. 63 fossil species of, i. 82 ; ii. 154 Edinburgh, building-stone of . ii. 471 Ehrenberg's account of Infusoria ii. 60 Ehrenbreitstein, contortions of the Devonian strata at . . i. 173 Eifel, Devonian rocks of . i. 170 Elba, iron ores of . . ii. 266 open workings at Rio . ii. 416 Electrical theory of the filling of mineral veins . . ii. 276 VOL. PAGE Elephant, fossil species of, found in Siberia . . .i. 72; ii. 148 Elevation of land by an earth- quake . . i. 17 gradual, without earth- quakes . . i. 21 valleys of . . i. 37 Elk, Irish, see Megaceros. Ely Cathedral, stone of . . ii. 463 Embankments and cuttings ii. 441 Enaliosaurians, account of . i. 340 Encrinites, account of . . i. 268 Encrinites moniliformis . i. 299 Endogem'tejs . . . . i. 433 Endogenous plants, account of i. 250 England, Geological structure of ii. 221 its advantages over other countries in its iron ores and coal ii. 397 Eocene beds, meaning of . ii. 8 of Europe . ii. 22 Equisetaceae . . . i. 252 Erratic blocks or boulders . ii. 115 Eruption of the Geysers, account of ii. 516 Eruption of Volcanoes . i. 1 6 Eryon arctiformis . . . i. 379 Erzgebirge, mines of . . ii. 266 Escarpments, meaning of the term i. 33 Etna, eruptions of . i. 18 Eugeniacrinites caryophyllatus . i. 393 Euomphalus i. 274 European volcanoes . . i. 15 Existing causes, importance of, in Geology . . . i. 24 Exogenous plants . . . i. 249 ' Exploitation des mines' ii. 236, 285 Explosive gases in coal-mines ii. 3 4 1,370 Exposure to atmospheric agents, effect of, in producing the de- composition of building-stones ii. 453, 478 Extinct species, distribution of, in the older rocks . . i. 125 Extinction of species, gradual i. 71 Eyes of Trilobites . . i. 130 GENERAL INDEX. 551 F. VOL. PAGE Faboidea ovata . . . ii. 54 Fahlun, copper mines of . ii. 415 Falconer and Cautley, their re- searches in Indian Geology ii. 99 Falkland Islands, Silurian rocks of i. 120 Falkland Islands, stream of stones in ii. 125 Fascicularia auranUum . . ii. 18 Fault, meaning of in Geology i. 36 springs on a line of . ii. 513 Faults in coal strata . . ii. 329 advantage of, in coal- fields . ii. 329, 330 effects of, in draining . ii. 503 Favosites, distribution of . i. 126 polymorphus . i. 174 Felling colliery, accident in ii. 381 Felspar, description of . ii. 177 Fen land, origin and condition of ... ii. 496, 498 Fen land of England, its condition in the time of Stephen . ii. 499 Fen land, method of draining fol- lowed ii. 500 Ferns, description of . i. 254 tree, magnificent appear- ance of . . i. 254 Ferruginous character of the lower grensand . . . i. 451 Fertility of soils, cause of ii. 483, 486 Fichtelgebirge, granite of the ii. 181 Fiery seams in coal-mines . ii. 371 Figs fossil . . . . ii. 55 Filling up of mineral veins . ii. 274 Fingal's Cave, basaltic rocks of ii. 202 Finland, gravel of . . ii. 123 Fire, in coal seams . . ii. 331 Fire-damp, nature of . ii. 342,370 accidents from explo- sion of, in the Walls- end colliery . ii. 374 accident in Jarrow col- liery from . . ii. 375 VOL. PAGE Fire-damp accident in Felling col- liery from . . . ii. 381 Fire-stone of the upper green- sand . . . . i. 453 Fish, description of . . i. 66 common in a fossil state i. 83 classification of . . i. 181 scales of recent species i. 184, 185, 186 tails of, homocercal and he- terocercal i. 185 Fish, fossil remains of, in Wenlock beds . i. Ill Upper Ludlow rock . i. Ill Old red sand- stone . i. 186 Carboniferous series . i. 277 Magnesian lime- stone i. 279, 505 New red sand- stone . i. 301 Aust beds i. 314 Lias . i. 334 Oolites . i. 402 Weald . i. 435 Cretaceous series i. 484 Tertiary rocks ii. 70 Fish-lizard, see Ichthyosaurus. Flagstone, nature of . . ii. 414 Flats, a particular condition of mineral veins . . . ii. 249 Flints in chalk, structure of i. 474 fossil species . i. 475 ,, a good road material . ii. 445 Flintshire, coal-field of . i. 208 lead and zinc ores of ii. 311 Folkstone, view of . . i. 490 Footmarks of animals in the New red sandstone . . i. 307 Foraminifera, account of . ii. 62 of the chalk . i. 478 Forbes, Prof. E., on the distribu- tion of mollusca . . i. 497 552 GENERAL INDEX. VOL. PAGE Forbes, Prof. E., on the fossil species ofCreseis . . i. 136 Prof. J., on the erratic blocks of the Jura - . . . ii. 123 Forces, Crystalline and Polar i. 40 Foreign Silurian rocks . i. 1 1 4 Devonian rocks . i. 163 Carboniferous rocks i. 219 Liassic rocks . . i. 316 Oolitic rocks . . i. 371 Wealden formations i. 428 Cretaceous rocks . i. 459 Tertiary formations ii. 22, 87, 105 Forest marble . . . i. 361 Forfarshire, stream of stones in ii. 125 building-stone in the Old red sandstone of ii. 470 Formation of soils by decomposi- tion of underlying rocks . . ii. 484 Formations, principal groups of i. 88 Fossiliferous rocks, subdivisions of i. 92 Fossils, nature of . . . i. 49 mode of preservation of i. 51 characteristic of forma- tions. . . i. 54 difficulty of determining the remains of Vertebrata i. 73 relative abundance of dif- ferent kinds of . i. 81 of the older Palaeozoic pe- riod ... . i. 124 of the middle Palaeozoic period . . i. 174 of the newer Palaeozoic period. Plants i. 245 Animals i. 267 of the New red sandstone and Triassic system i. 296 of the Lias Invertebrata i. 320 Vertebrata i. 334 of the Oolites, Plants, &c.i. 383 Invertebrata i. 388 Vertebrata i. 402 Fossils of the Weald . . i. 431 of the Cretaceous system i. 471 of the European Tertiary beds . . . ii. 51 of the Asiatic Tertiaries ii. 98 of the American Tertiaries ii. 113 of the Caverns and Gravel ii. 139 Fossils injurious to building-stones ii. 456 Foundations of buildings, selection of sites for . . . ii. 450 Fountain, natural Artesian ii. 521 Fowey Consols mine, number of lodes worked ii. 292 depth of . ii. 293 Fox, Mr. R. W., his experiments concerning the cause of slaty cleavage i. 39 .his theory of the filling of mineral veins ii. 276 Fragmentary state of the fossils of mammals . . . i. 73 France, Silurian rocks of . i. 119 Carboniferous system in i. 224 Triassic rocks of . i. 294 Oolitic rocks of . i. 371 Cretaceous beds of i. 459 older Tertiary beds of ii. 22 middle Tertiaries of ii. 33 mining districts of . ii. 264 (Central) Volcanoes of ii. 210 Franconia, Oolitic rocks of . i. 377 Freestone not always the best ma- terial for a building-stone ii. 453 French Alps, mining districts of ii. 265 Freyberg (Saxony), systems of veins in . . . ii. 255 Friesdorf, alum clay of ii. 48, 408 Frondiculina oblonga . ii. 63 Fronds of ferns . . . i. 251 Frost, action of, on soils . ii. 485 Fulham, Artesian wells at . ii. 526 Fullers' earth beds of the Oolites i. 359 Furnace, Re verberatory, section of ii. 309 GENERAL INDEX. 553 Furnace Blast, section of . ii. 395 use of in ventilating coal- pits . . . . ii. 349 Fuse, safety . . . ii. 299 Fusulina . . . i. 223 Fusus asper . . . ii. 10 bulbiformis . . ii. 25 G. Gailenreuth, cavern of . ii. 134, 135 Gailkmella distans . . ii. 60 Galena . . . . ii. 308 Galicia, Tertiary beds of . ii. 40 Gamlingay, Lower Greensand beds of . . i. 451 Ganges, delta of the . . i. 7 Garonne, basin of the . ii. 34 Gas evolved from mineral springs ii. 514 Gasteronemus, account of . ii. 73 Gasteropoda, description of . i. 67 Gatherly Moor, quarries of ii. 473 Gatton, Greensand quarries of ii. 476 Gault . . . . i. 451 General views, importance of, in Geology . . . i. 48 Generalisations in Geology i. 47, ii. 533 Geographical distribution of mine- ral veins ii. 262 Geological formations, derivation of soils from ii. 490 relative value of, in agriculture ii. 490 phenomena, difficulty of connecting them with existing works of Na- ture . . i. 93 phenomena accompany- ing thermal springs ii. 514 railway sections ii. 448 theory, nature of . ii. 533 Geology, definition of i. 1 nature of . . ii. 532 Descriptive . . i. 85 Practical . ii. 231 VOL. PAGE Geology, its application to Mining ii. 244 w ,, Engineering ii. 436 n Architecture ii. 450 ,, Agriculture ii. 481 Physical . . ii. 532 Georgia, U. S. Tertiary Geology of ii. 109 Germany, Wealden deposits in i. 428 mines of . . ii. 266 Gervillia, n. s. . . i. 320 ' Getting' coal . . ii. 359 Geysers, or boiling springs of Ice- land . . . ii. 515 ,, account of an eruption of the . . ii. 516 explanation of the . ii. 517 Giants' Causeway, account of ii. 212 Gibraltar, caves of . . ii. 137 Giffneuch (near Glasgow) quarries of .-.. . . ii. 472 Girgenti, section at . ii. 45 Glaciers, account of . . i. 11 effects produced by ii. 131 theory of the motion of ii. 131 Claris, altered slates of the Creta- ceous period in the Canton of i. 184, 466 Glasgow, building stones of ii. 472 condition of buildings of . . '. ' ii. 472 Glastonbury, Abbey of, its condi- tion . . . ii. 462, 475 Glen-da-lough, vale of . ii. 261 Glyptodon, account of . . ii. 161 Glyptolepis, account of . i. 194 Gneiss . . . . ii. 189 Golcondah, diamond sandstones of ii. 97 Gold, proportion of, in the auri- ferous sands of Asiatic Russia . ii. 267 ores of, in Russia . ii. 320 region, in the United States ii. 270 Gomphoceras pyr iforme . i. 142 Goniatites, account of . . i. ] 80 554 GENERAL INDEX. VOL. PAGE Goniatites striattis . . i. 275 Goniopholis, account of . . i. 437 Gosau, valley of . . i. 467 Gosforth, fault in coal-mine at ii. 330 Grampians, granite of . . ii. 182 Granite, account of . . ii. 179 ,, of the Grampians . ii. 1 82 supply of, in England ii. 479 Granitic rocks, account of . ii. 175 Grantham church, stone of . ii. 464 Graptolites, account of . i. 127 foliaceus . . i. 128 ludensis . . i. 128 Grauwacke", meaning of . i. 96 rocks, see Palaeozoic. Gravel, nature of . . . ii. 115 origin of . . ii. 119 fossils of, in Northern Europe . . i. 72 stanniferous . ii. 282 Great Oolite . . . i. 359 Greensand fonnation . i. 448 Lower . . i. 448 Upper . . i. 453 Greenstone . . . ii. 185 Grenelle, Artesian well of . ii. 526 Grenoble, mining district of ii. 265 Gresbigarre i. 294 de Vosges . . i. 242, 294 Grey copper ore . . ii. 303 Grey wacke, see Grauwacke. Grignon, shells of . ii. 25 Grind of the Navir, Shetland Isles . . . . i. 12 Gryphite limestone . . i. 317 Gryphcea incurva . . i. 320 ,, virgula, a characteristic fossil . . i. 374 Guadaloupe, recent fossiliferous limestone of ... ii. 137 Guanaxuato, silver vein of ii. 316 Guaranian series, S. America ii. Ill Guiana, deposits on the coast of i. 8 Gujerat, Geology of . . ii. 93 Gunpowder, use of, in mines ii. 298 Gymnosperms . . . i. 259 VOL. PAGE Gypsum of New red sandstone i. 292 Gypsum of Montmartre ii. 27, 405 uses of ... ii. 405 Gyrodus, description of . . i. 403 gracilis . . i. 402 Gyrogonites . . . ii. 97 H. Hachenburg, brown coal of . ii. 49 Hade of a vein, meaning of the term ii. 250 Haematite, veins of . . ii. 313 Hamilton, Mr., his account of the Geology of Asia Minor . ii. 89 Hamites attenuatus . . i. 483 Hammersmith, Artesian well at ii. 526 Hampshire Basin, account of . ii. 12 Hampstead, London clay of ii. 15 Harbours, breakwaters, &c. . ii. 446 Hardness (relative) of rocks ii. 297 Harlech Castle, Merionethshire i. 113 Harpa mutica ii. 25 Hartz, mining district of . ii. 266 Harwich, London clay of . ii. 1 3 Hastings sand . . . i. 424 quarries in . ii. 476 Headon Hill, London clay of ii. 15 Heaton Main colliery, accident at ii. 384 Heddon quarries, Newcastle ii. 472 Henwood, Mr., on Cornish metal- liferous deposits ii. 256 on pipe veins . ii. 249 Herborn, Posidonia-schists of i. 167 Herefordshire, section across i. 146 Heterocercal tail of fish, meaning of i. 185 Hetton colliery, drowning of ii. 434 High Main seam, Newcastle coal- field . . . . ii. 336 Highgate, London clay of . ii. 15 Hightea fusiformis . . ii. 54 Hildburghausen, fossil footmarks in the New red sandstone of i. 307 GENERAL INDEX. 555 VOL. PAGE Himalayan chain, Oolites of . i. 381 Himalayan chain, Tertiaries of the flanks of . . ii. 95 Hindoo Koosh, Geology of . ii. 91 Hippopodium ponderosum . i. 320 Hippurite limestone . . i. 465 Hippurites bioculata . . i. 466 Hitchcock, Prof., his account of the footsteps of birds in the New red sandstone of Con- necticut . . . i. 312 Holoptychius., account of . i. 195 scale of . i. 198 Homocercal tails of fish . i. 185 Honfleur, Oolitic beds at . I. 374 Hopkins, Mr. Evan, his work on the connexion of Geology with terrestrial magnetism . ii. 278 Hopkins, Mr. W., his speculations on Physical Geology . ii. 224 Hordwell cliffs, London clay ii. 1 5 Hornblende, description of . ii. 178 rock . . ii. 185 Hornstone . . . . ii. 185 Hot-blast, use of, in the manufac- ture of iron . . . ii. 393 Hot Springs, European . ii. 514 House-architecture, building mate- rials . . . . ii. 452 Huddlestone Quarries and Hall ii. 469 Huel Fortune -mine, split vein of ii. 247 Humus, definition of . . ii. 483 Hungary, mines of . . ii. 266 Hutton seam, Newcastle coal- field . . . ii. 336, 339 Huttonian, hypothesis of the fill- ing of mineral veins . ii. 275 Hycena, fossil species of . ii. 141 jaw of . . ii. 143 Hybodus, Ichthyodorulite of . i. 339 Hydrabad, Geology of . ii. 92 Hydrostatic paradox . . ii. 523 Hylaeosaurus, account of . i. 438 Hypogene rocks . . . ii. 185 Hyracotherium, account of ii. 83 I. VOL. PAGE Icebergs, gravel conveyed by . i. 11 Iceland, silex in the springs of ii. 31 volcanic eruption in . i. 19 hot springs of . ii. 515 Ickthyodorulites, account of . i. 337 Ichthyolite bed of Gamrie, N. B. i. 287 Ichthyology, classification of, i. 183 Ichthyosaurus, account of . i. 341 communis (tooth of) i. 345 (left fore paddle of) i. 345 Identification of strata by fossils i. 54 ii.2, 171 Idria, quicksilver mines of ii. 272, 321 Igneous rocks, account of . ii. 168 Igneous theory of the filling of mineral veins . . ii. 275 Iguanodon, account of . . i. 439 (tooth of) . i. 441 Improvement of land by drainage ii. 504 Inclination of strata from the hori- zon .... i. 29 Inclined seams of coal . . ii. 361 India, northern, Lias of . i. 319 north-western, Geology of i. 381 southern, Cretaceous rocks of . . . . i. 469 Tertiary Geology of, ii. 91 fossils of . . . ii. 98 granite of . ii. 183 volcanic district of . ii. 211 Inferior Oolite . . i. 358 building-stone of ii. 461 Infusorise, account of . . ii. 59 fossil species of . ii. 69 uses of . . ii. 61 Injection of metallic ores, theory of ii. 275 Ink-bag of Cephalopoda . i. 333 Inoceramus sulcatus . . i. 455 Insects of the Oolitic rocks . i. 395 of the Wealden beds i. 435 556 GENERAL INDEX. VOL. PAGE Insects of Tertiary formations ii. 67 Interception of springs by deep draining . . . . ii. 506 Intermittent springs . . ii. 518 Intersecting veins . . ii. 259 Invertebrata, arrangement of i. 58 subdivisions of i. 66 species of, most com- monly found fossil . i. 83 Ionian Islands, Cretaceous beds i. 464 Tertiariesof ii. 41 Ireland, mining districts of . ii. 263 Irish beds of Old red sandstone i. 161 Carboniferous period i. 216 Cretaceous period i. 458 Irish Elk, see Megaceros. Iron ore occurring in mineral veins . . . ii. 313 Iron mines, of England . . ii. 390 mining records of ii. 433 Iron, quantity manufactured in England in the year 1835 ii. 396 Ischia, Island of . . . ii. 45 Isopods of the Wealden . i. 434 Italy, mineral riches of . ii. 266 Alabaster of . . ii. 406 Ivory, fossil, from the North Pole . . . i. 72 J. Jackdaw Craig, quarries of . ii. 468 Jarrow colliery, accident at . ii. 375 Jet, nature of . . . ii. 408 Jets of gas in fiery seams of coal ii. 371 Jigging, a mining process . ii. 304 Johnson, Mr., on drainage . ii. 504 Jointed structure of slates . ii. 199 granite ii. 200 sandstone, pro- duced by heat . . ii. 200 Joints and cleavage explained i. 38 direction of . i. 40 Jorullo, eruption of . , i. 17 view of i. 25 VOL. PAGE Jubbulpoor, Tertiary beds of ii. 97 Julian Alps, limestone of . i. 464 Jura-kalk formation . i. 356, 575 Jura, Oolites of the . . i. 375 Tertiary valleys of the . ii. 36 erratic blocks of the . ii. 122 K. Kalowala Pass, fossils found there . . . . ii. 96 Kangaroo, gigantic fossil species of ii. 164 Karst limestone . . i. 464 Kelloways rock . . i. 362 Kenton quarries, Newcastle ii. 472 Kentucky, Big Bone Lick ii. 130 Ketton stone, its value as a build- ing material . . . ii. 462 Keuper . . . . i. 295 Kiesel-schiefer . . i. 220 Kimmeridge clay . . . i. 365 coal . i. 366, ii. 410 Kirby Ireleth, slates of i. 96, ii. 414 Kirkdale cavern, account of ii. 143 Kit Hill, stanniferous gravel of ii. 253 Kunkur, account of . ii. 93, 133 Kupfer-schiefer . . i. 242 Kyson in Suffolk, London clay of . . ii. 15 L. Labyrinthodon, account of . i. 309 Lachow Island, bones from ii. 124 Lahn, Devonian rocks of the i. 167 Lamna, teeth of . . . i. 487 Lanarkshire, iron-stone bands in ii. 393 Lancashire coal-field . . i. 211 Land, valuation of, influenced by Geological considerations ii. 494 Land-slips, often the effect of at- mospheric action on exposed beds i. 14 GENERAL INDEX. 557 VOL. PAGE Land Springs . . . ii. 511 Later! te of India, its origin ii. 183 Lava, appearance and nature of ii. 203 cut through by a river course . . i. 12 great eruption of . . i. 20 identical with basalt ii. 205 Law of mutual relations of struc- ture and habit . i. 74 Lead mines of England ii. 263, 338 ores preparation of . ii. 308 Leckhampton, lower Oolite of i. 361 Leeds, quarries near . . ii. 474 Legislative enactments of the mining districts of the Hartz ii. 422 of Saxony ii. 426 $, of England ii. 426 Leguminosites, account of . ii. 57 Leinster coal-field . . i. 217 Leiodon, account of i. 489 Lepidodendron sternbergi . i. 256 Lepidophyllus . . . i. 259 Lepidostrobus ornatus . i. 259 Lepidotus, account of . . i. 335 Wealden species of i. 436 Leptaena depressa . . i. 1 32 Leptolepis, description of . i. 403 voighti . . i. 402 Letten, nature of the bed . i. 243 Levels in mines . . ii. 288 in coal-mines . . ii. 340 Lewis, curvatures of gneiss in ii. 192 Lias, formation of . , i. 313 Fossils, Invertebrate . i. 320 Vertebrata . . i. 334 character of the soil on, ii. 491 Libellula longialata . . i. 395 Lignite, deposits of . . ii. 327 working beds of . ii. 409 Lily Encrinite (Encrinites monili- formis) i. 299 Limestone, its qualities as a road material . ii. 445 different kinds of, used as building-stones ii. 454 VOL. PAGE Limestone, the best building ma- terial . ii. 478 Magnesiari . i. 232 building- stones of ii. 465 sometimes a barren soil . . ii. 489 Limnaea longiscata . . ii. 1 Limulus, description of . i. 394 Lincolnshire, churches of . ii. 464 Lindley, Prof., his experiment on plants i. 248 Lineolaria costata . . ii. 63 Linlithgow, sandstone quarries of ii. 471 Lisbon, Cretaceous limestone of i. 467 Tertiaries of . . ii. 40 Lifhostrotion striatum . i. 267 Littorina littoreus . . ii. 18 Lituite , . . . i. 141 Llandeilo flags . . . i. 103 Llangollen, Ludlow rock near i. Ill Mountain limestone es- carpment at Dinas Bran, near . i. 33 Lodes, or loads, meaning of the term . . . . ii. 250 Loire, basin of the . . ii. 34 London clay, account of . ii. 1 1 Artesian wells in ii. 526 fossil fruits of . ii. 54 corals of . ii. 58 placoid fish of . ii. 75 agricultural charac- ter of . ii. 493 Long method of working coal ii. 347 Lonsdale, Mr., his examination of the South Devon corals . i. 157 Louisenberg, decomposed granite of .... ii. 181 Lower New red sandstone . i. 231 building-stone of ii. 474 Oolites . . i. 358 Greensand . . i. 448 Ludna concentrica . . ii. 25 menardi . . ii. 43 558 GENERAL INDEX. VOL. PAGE Ludlow limestone . . i. 109 rock, lower . i. 108 upper . . i. 110 Lulworth Cove, section of . i. 424 Luxemburg, Geology of . i. 317 Lycopodiacese . . . i. 258 Lyme Regis, Lias of . i. 315 M. M'Culloch, Dr., on the Western islands of Scotland . . i. 151 Macrauchenia, account of . ii. 153 Macropoma, account of . i. 485 Madeira, recent sandstone of ii. 137 Maestricht, chalk of . i. 461 Magnesia, a constituent of soils ii. 489 Magnesian limestone series . i. 229 Magnesian limestone conglomerate i. 237 building-stone of ii. 465 the best kind of building-stone in England ii. .478 its agricultural character ii. 490 Malachite, large block of . ii. 268 Malcolmson, Dr., on the Old red sandstone of Scotland . i. 151 Malcolmson, Dr., his account of In- dian Geology . . . ii. 96 Malm-rock i. 453 Mai ton, coral rag of . . i. 365 Mammalia, account of . i. 59 fragmentary condition of fossil bones of i. 73 ,, rarely found fossil, except in Tertiary rocks . i. 81 of the Stonesfield slate i. 419 Mammaliferous or Norwich crag ii. 1 8 Mammoth or Fossil Elephant i. 72, ii. 148 VOL. PAGE Man, his remains only found fossil in the most recent formations i. 81 Manganese, ores of . . ii. 312 Mansfield, quarries of New red sandstone at . . ii. 474 Mantellia (Cycadites) . . i. 387 Maps, Geological, nature of i. 44 value of, in prac- tical Geology ii. 237 Marginella ovulata . . ii. 25 Marginulina sulcata . ii. 63 Marine currents, force of . i. 12 Marlstone of the Lias . i. 315 Marnes irisees . i. 295 Marsupialia, account of . i. 62 fossil, in secondary rocks . i. 81, 419 Marsupites ornatus i. 479 Martha's Vineyard, Tertiary beds of i. 108 Massive, technical meaning of the term in Mineralogy . ii. 177 Mastodon, account of . . ii. 151 tooth of . . ii. 152 Mastodonsaurus, see Labyrinthodon. Masulipatam, Tertiary Geology near . . . . ii. 97 Matlock, hot springs of . ii. 514 Mechanical action of the atmo- sphere on stones ii. 478 use of the soil to vege- tables . ii. 486 Mediterranean, Miocene Tertiaries of . ii. 41 Megaceros Jiibernicus (head of) ii. 146 Megalichthys, account of . i. 278 Megalochelys atlas . . ii. 100 Megalosaurus, account of . i. 408 tooth of . . i. 409 Megatherium, account of . ii. 157 Melania turritellaris . i. 296 Mendip hills, Geology of . i. 314 mines of . ii. 311 Mercury, ores of . . ii. 321 Merstham, greensand of . ii. 476 Metalliferous ores, indications of ii. 280 GENERAL INDEX. 559 VOL. PAGE Metals, relative age of . . ii. 273 Metamorphic rocks . i. 94 ; ii. 188 Meteoric stones . ii. 313 Mewar, Indian province of . ii. 93 Mexican mines, produce of . ii. 320 Mexico, Volcanoes of . . i. 1 6 Mica, description of . . ii. 178 Mica-schist . . . ii. 193 Microscopic structure, how far it is of value in classification i. 251 Middle Palaeozoic period . i. 146 fossils . i. 174 Miliola, a characteristic fossil, ii. 63 Miller, Hugh, on the Old red sandstone of Scotland . i. 151 Minchinhampton, Oolite of . i. 361 Mineral composition of strata i. 28 soils ii. 482 produce, relative value of, in different countries ii. 303 Springs . . ii. 513 veins, definition of . ii. 246 filling up of . ii. 274 newer than the rock enclosing them ii. 258 crossing one another ii. 244, 259 distribution of ii. 261 ideal section of ii. 289 Mineralogy, its value in Geology i. 1 ; ii. 171 Mining districts of England ii. 262 France ii. 264 Spain ii. 265 Germany ii. 266 Scandinavia ii. 267 Russia ii. 267 South America ii. 268 North America ii. 270 Mining, its relation to Geology ii. 234 Records, Museum of ii. 242 nature of . ii. 421 regulations of the Hartz ii. 422 of England ii. 426 VOL. PAGE Mining regulations of Saxony ii. 426 Miocene beds, meaning of . ii. 8 in Europe . ii. 33 Moa, see Dinornis. Modiola? . . . ii. 18 Molasse of Switzerland . ii. 36 Moldavia, Cretaceous beds of i. 462 Mollusca, account of . i. 67 distribution of in the ^Egean Sea . i. 497 their value in the classifi- cation of Tertiary form- ations . . ii. 7, 68 Tertiary species of . ii. 67 Monk-Wearmouth Colliery, deep sinking at . . . ii. 339 Monk-Wearmouth Colliery, head of water at . . . ii. 524 Monkeys, fossil . i. 81, ii. 99 Monmouthshire, building-stone of ii. 470 Monocotyledonous plants . i. 250 Mont Blanc, Granite of . ii. 182 Mont Martre, fossil quadrupeds of . ii. 80 gypsum of . ii. 406 Monte Bolca, Tertiary beds of ii. 32 fossil fish of . ii. 71 Montpellier, Miocene beds of ii. 34 Moraines, nature of . i. 11; ii. 131 Morea, Geology of the . i. 465 Mosasaurus Jioffmanni (head) i. 487 Mould, vegetable . . ii. 483 Mudstone of the Silurian rocks i. 109 Mulatto of Ireland . . i. 458 Munster, Coal fields of . i. 217 Murchison, Mr., his establishment of the Silurian system . i 101 and Sedgwick, their determination of the Devonian system . . . i. 156 Murchisonia intermedia . i. 177 Murextubifer . . . ii. 10 Muschelkalk i. 294 Museum of Economic Geology ii. 242 560 GENERAL INDEX. VOL. PAGE Mutual relation of structure and the habits of animals . i. 74 Myliobates toliapicus (tooth) ii. 75 Mylodon, account of . ii. 155 robustus . . ii. 156 Myophoria vulgaris . . i. 296 Myrmecium globatum . . i. 365 N. Nagelfluhe ... . ii. 36 Nairn river, floods of . . i. 1 Namur, rocks near . . i. 228 Nancy to the Vosges, section i. 293 Nantwich, rock-salt of . ii. S99 Naples, Tertiary Geology of ii. 45 Nassa elegans . . . ii. 18 Nassau, Silurian rocks of . i. 116 Devonian rocks of . i. 167 Lignite of . . ii. 49 Natica cepacea . . . ii. 25 subcostata . . i. 177 Natural drainage . . ii. 497 Nautilus, description of . i. 138 decussatus . . i. 320 Nave encrinite, (Actinocrinites,) i. 271 Necker, M-, his investigations concerning mineral veins . ii. 271 Necker, M., his theory of the filling of mineral veins by sub- limation . . . . ii. 274 Nelly's Cove, Cornwall, raised beach at ... i. 21 Nematoneura, subdivisions of i. 68 Neocomien beds . . i. 429, 460 Nerinaea, description of the genus i. 397 Nerinaean limestone . . i. 376 Neritina conoidea , ii. 25 Netherlands, Basin of the . ii. 28 Neuchatel, Cretaceous beds of i. 460 Neuhoffhunger-flachen mine, cross- ing of two veins in . . ii. 244 Neuropteris flexuosa . i. 245 VOL. PAGE Newcastle coal-field, account of i. 213; ii. 336 value of the coal ex- tracted from ii. 325 accidents in . ii. 386 building-stone of ii. 472 Newcastle-on-Tyne, view of . i. 218 Newer Palaeozoic period . i. 199 New Holland, Silurian rocks of i. 120 New red sandstone, Lower . i. 231 Upper . i. 288 quarried for build- ing-stone, near Stafford . ii. 474 soil of . ii. 491 New Spain, silver mines of . ii. 315 method of working the mines . ii. 317 New Zealand, vegetation of . i. 387 gigantic fossil bird of . . . . . . ii. 164 Nickel ii. 323 " in meteoric stones . ii. 313 Nidder, Weald en beds in the val- ley of i. 427 Nipa, account of . . . ii. 55 Nipadites elegans . . ii. 54 Nismes, fountain at . . ii. 524 Norfolk or Norwich crag . ii. 18 rich artificial soil of ii. 493 Norfolk Island pine(Araucaria) i. 257 Normandy, Oolites of . i. 371 North American Silurian rocks i. 120 Devonian rocks . i. 173 Carboniferous rocks i. 226 Cretaceous rocks . i. 468 Tertiary rocks . ii. 106 mines . . ii 270 Northumberland, mining district of .... ii. 263 Norway, Silurian rocks of . i. 118 Norwich, or Mammaliferous crag ii. 18 Notagogus denticulatus . i. 402 Nothosaurus mirabilis (cranium) i. 304 GENERAL INDEX. 561 VOL. PAGE Nova Scotia, Carboniferous series of i. 227 Noxious gases in coal-mines, ac- count of . . . ii. 341, 370 Nucula poll . . . ii. 43 Nummulties, account of . ii. 26, 64 nummiformis . ii. 63 limestone . i. 465 0. Oak-tree clay of the Weald . i. 427 Oban, view of . . i. 155 Oberland Alps, view of . ii. 168 Obsidian ... ii. 204 (Eningen, fossiliferous beds of ii. 49 Older Palaeozoic rocks, circum- stances of their deposit . i. 121 Old red sandstone of Herefordshire i. 146 Scotland . i. 151 Old red sandstone conglomerate, origin of . i. 284 building- stone of ii. 470 an excellent soil ii. 490 Olefiant gas in coal mines . ii. 373 Oliva nitidula ii. 25 Oodipoor, Geology of . . ii. 94 Oolites, lower . . i. 358 middle . i. 362 upper i. 365 foreign . . . i. 371 building- stones of the ii. 456 value of, in agriculture ii. 491 Oolitic system, rocks of the . i. 356 limestone, rate of decompo- sition of . . ii. 477 Open workings for metallic ores ii. 415 Operculina complanata . ii. 63 Ophioderma egertoni , . i. 325 Ophiurella carinata . . i. 392 Ordnance Geological Survey . ii. 237 Ore, distribution of . . ii. 273 Organic remains, see Fossils. VOL. II. VOL. PAGE Organic matter, per centage of, in soils . . . ii. 485 Orkney Islands, Geology of . i. 153 Ornithorhynchus, its analogies with the Ichthyosaurus . i. 344 Orlhoceratites, account of . i. 141 laterale . i. 277 simmsi . i. 277 Osmeroides microcepJutlits . i. 486 Ossiferous caverns . ii. 1 34 Osteolepis, account of . . i. 195 Ostrea canaliculata . . i. 455 Otopteris acuminata . . i. 386 Otter, fossil, of the crag . ii. 145 Overman, his duty in a colliery ii. 357 Outcrop, meaning of the term in Geology . . . i. 33 of coal, different kinds of ii. 332 Owen, Professor, his arrangement of reptiles . . i. 303 Oxford clay i. 362 P. Pachydermata, subdivisions of i. 64 interest attaching to fossil species of . . i. 82 fossil Indian spe- cies of . ii. 101 Pachyodon (Cardinia) listeri i. 320 Pagurus (Hermit crab) of the chalk i. 480 Pagus, Mount . . . ii. 89 Palceoniscus, account of . i. 280 Palaeontology, meaning of . i. 54 general result of the pursuit of . i. 84 Palseophis ii. 78 Palseotherium . . . ii. 81 Palaeozoic rocks, meaning of i. 91 arrangement of i. 94 Palaeozoic period, general condi- tion of the globe during the . i. 283 2 o 562 GENERAL INDEX. Paludina lenta unicolor VOL. PAGE . ii. 10 ii. 18 Pampas clay formation . ii. 112 Pandaneae . . . ii. 55 Pandanocarpum . . . ii. 55 Pannel-work, meaning of . ii. 345 ventilation by means of . . ii. 356 Paper Coal of the Rhine valley, ii. 48 fossils of . ii. 53 Paramoudra . i. 476 Paris, remarkable Artesian well in .... ii. 526 Paris Basin, account of . ii. 22 Paris, Plaster of . . ii. 27, 405 Park nook, quarries of . ii. 467 Parker's Cement . . ii. 13 Parliament, New Houses of, stone selected for the building . ii. 466 Pasco Silver Mines, produce of ii. 270 Patagonia, gravel of . ii. 126 recent sandstone of ii. 138 Patagonian Tertiary series . ii. Ill Patella (Equalis . . ii. 18 Pays de Bray, Wealden beds of i. 428 Peat bog, nature of . . ii. 501 ,. bursting of . ii. 501 drainage of . ii. 497, 502 Pecopteris mantelli . . i. 245 Pectuneulus scalaris . ii. 10 Pennsylvania, anthracitic coal of . i. 226 method of working coal of . ii. 363 Penrhyn, slates of . . ii. 196 slate quarries . ii. 413 Pentacrinites subangularis . i. 323 Pentamerus, account of i. 1 35 gryphus . i. 177 JmigUi . . i. 110 Penlremites inflatus . . i. 271 orbicularis . . i. 271 Percy main colliery, ventilation of .... ii. 353 Permian System . . . i. 239 Perthshire, building stone of . ii. 470 VOL. PAGE Peru, mines of . . . ii. 269 Peterborough cathedral, stone of ii. 463 Peuce . . . . i. 321 Phanerogamous plants . i. 250 Phascolotherium . . . i. 419 Phasianella? . . . i. 383 PMadomyafidicula . . i. 397 Phragmoceratite . . i. 141 Phyllodus polyodus (tooth) . ii. 76 Physical Geology . . ii. 532 Phytosaurus (Labyrinthodon) i. 309 Pileolus plicatus . . i. 383 Pileopsis cornu-copice . . ii. 25 Pillars, working out the . ii. 345 Pinites . . . i. 260, 322 Piot, M., his account of the coal district of the north of England ii. 334 Pipe-veins ii. 249 Pitching-veins, workings in . ii. 362 Placoid fish, account of i. 185 ; ii. 74 Plagiostoma giganieum . . i. 320 spinosum . i. 481 Plantigrade carnivora, habits of i. 62 Plants, fossil, of Carboniferous se- ries . . i. 245 New red sand- stone . i. 297 Lias . . i. 321 Oolites . i. 384 Tertiary deposits ii. 53 Plaster of Paris . '. ii. 27, 405 Plastic clay . . . ii. 12, 24 Platax, account of , . ii. 73 Platysomus, account of . i. 281 Playfair, Professor, his opinion of glaciers . . . ii. 131 Pksiosaurus, account of . i. 351 macropterus (left fore- paddle) . i. 345 Pleurotoma transversaria . ii. 25 Pleurotomaria (u. s.) . . i. 397 anglica . . i. 320 Pliocene beds, explanation of ii. 8 of Europe . ii. 42 GENERAL INDEX. 563 VOL. PAGE Pliosaurus, account of . . i. 405 Plutonic rocks . . ii. 185 Plymouth limestone . . i. 161 Podolia, Miocene beds of . ii. 40 Poikilopleuron, account of . i. 406 Poland, Cretaceous beds of i. 462 Miocene deposits of . ii. 40 Salt mines of Wieliczka, in ... ii. 401 Polar and crystalline forces, nature of i. 40 Polir-schiefer . . . ii. 60 Polished and striated rocks . ii. 1 32 Polymorphina regularis . ii. 63 Polypothecia . . . i. 477 Polyps, structure of . i. 69, 268 Pondicherry, fossils of . . i. 470 Porphyry . . .. ii. 183 Portland Island, quarry in . i. 422 view of . ii. 531 sand . . . i. 367 stone . . i. 366 its value for build- ing purposes ii. 456 durability of ii. 459 Portlock, Capt., on the Geology of the Ionian Islands . i. 464, ii. 41 Posidonia-schist of Herborn . i. 167 Posidonia limestone (Lias) i. 318 Potosi, mines of . . . ii. 269 supply of silver obtained from . . ii. 316 Pounceford, Wealden beds of i. 423 Practical Geology, meaning of ii. 231 Preparation of ores . . ii. 302 President stone-quarries, Glasgow ii. 472 Pressure on the roof and floor of mines . . . . ii. 343 Primary fossiliferous rocks, see Palaeozoic. Primary rocks, see Plutonic. Productive soil, complicated ele- ments of ii. 489 Productive veins, direction of, in Cornwall . ii. 256 Productus, account of . fimbriatus VOL. PAGE i. 272 i. 275 L 273 Property, value of, influenced by geological considerations . ii. 494 Protogine of Mont Blanc . ii. 179 Protozoic group of rocks . i. 104 Provence, Tertiary beds of Aix in . ii. 31 Psammite i. 169 Pterichihys, description of . i. 190 Pterodactylus, description of i. 413 crassirostris . i. 416 Pterophiloides ricltardsoni . ii. 54 Pteropoda, account of . i. 67, 136 Pterosauria . . i. 354,413 Public buildings, materials of con- struction of ... ii. 452 Pumice-stone . . ii. 204, 217 Punjaub, Geology of the . ii. 91 Purbeck beds . . . i. 421 Island (section) . i. 366 marble . i. 423 Purpural . . . . i. 383 Puy en Velay, freshwater basin of .... ii. 30 Pycnodonts . . i. 404 ; ii. 76 Pygopterus, account of . i. 505 Pyrenees, altered limestone of i. 464 mining district of ii. 265 salt-works of . ii. 400 Pyrula . . . . ii. 35 nexilis . . . ii. 25 Q. Quader sandstein . i. 462 Quadrumana, account of i. 61 Quarries and open workings . ii. 411 Quartz, description of . ii. 177 Quartzite . . . . ii. 193 Quartzose conglomerate in the Old red sandstone . . . i. 129 Quebec, boulder formation of ii. 128 564 GENERAL INDEX. K. VOl. PAGE Radiata, subdivisions of . i. 68 Railroad, selection of a proper line ii. 437 Railway sections, value of, in Geo- logy ii. 448 Rain, its effect on the soil . ii. 485 distribution of . . ii. 529 Rain-drops, marks of, in sandstone i. 312 Rain-water, course of . ii. 510,529 Raised beaches, Cornwall i.21 ; ii. 138 Clyde Valley ii. 21 Raising ore from the bottom of mines . . . ii. 301 Rake vein, meaning of . ii. 296 Rana diluviana . . ii. 50 Rarefaction, ventilation of coal- mines by ... ii. 349 Rauwacke . . . i. 243 Records, mining, importance of ii. 421 nature of . ii. 428 for coal-mines ii. 432 Red crag . . . ii. 1 7 Registers, mining, preserved in the Hartz mines . . . ii. 424 Relation of structure to the habits of organised beings . i. 74 Rennes, Eocene beds of . ii. 31 Reptiles, definition of . . i. 65 classification of . i. 302 remains of, abundant in certain strata . i. 83 extinct species of, from the New red sandstone i. 303 extinct species of, from the Lias . . i. 340 extinct species of, from the Oolites . i. 404 extinct species of, from the Weald . i. 436 extinct species of the Cretaceous period i. 487 VOL. PAGE Reptiles, extinct species of, from the Asiatic Tertiaries . ii. 100 Results of Geological investigation ii. 536 Reverberatory furnace, explana- tion of ... ii. 309 Rhine, quantity of mud suspended in it . . i. 7 ,. Silurian rocks on its banks i. 115 Devonian rocks of . i. 166 Miocene beds in valley of ii. 37 its course through Germany ii. 37 Pliocene beds in the valley of ... ii. 47 volcanic district of . ii. 209 Rhinoceros, extinct species of ii. 148 RJiyncMites gaillardoti . i. 296 Urundo . . i. 296 Rhynchosaurus . . . i. 304 Richmond in Yorkshire, quarries - of . ii. 473 Richmond Castle, stone of . ii. 474 Rio, Isle of Elba, iron-mines of ii. 416 Ripple-marks in sandstone . i. 306 Rivers draining the fen district of the great level . . ii. 499 Roach beds of Portland stone ii. 457 Road-making and canals . ii. 436 Road materials . . ii. 444 Rocca, or rock, alum . . ii. 408 Roche Abbey, quarries near . ii. 466 ,, condition of . ii. 467 Rock, or Rocca, alum . . ii. 408 Rock-salt mines of Cheshire ii. 398 of Cardona . ii. 400 of Wieliczka in Poland . ii. 401 Rodentia, account of . i. 63 fossil species of . i. 82 Roemer, Von, his account of Ger- man Wealden deposits . i. 428 Ronca, Eocene beds of . ii. 32 JRostellaria, u. s. . . . i. 383 columbella . . ii. 25 GENERAL INDEX. 565 VOL. PAGE Rostellaria lucida . . ii. 1 Rothe-todte-liegende . i. 241 Rowley rag, experiment with the basalt of . . ii. 215 Rudistes, account of . i. 482 Ruminantia, account of . i. 64, 82 Asiatic fossil species ii. 101 Running water, force of i. 10 Russia, Silurian rocks of . i. 1 1 7 Devonian rocks of i. 170 Carboniferous system in i. 222 Permian System of . i. 239 Oolites of . . i. 380 Cretaceous rocks of . i. 462 Pliocene beds of . ii. 50 mineral riches of . ii. 267 gold ores of . . ii. 320 S. Safety fuse used in blasting . ii. 299 Safety lamps, invention of, by Sir H. Davy ii. 367 St. Etienne, coal-field of . i. 224 St. Helier's Bay, Isle of Jersey, ii. 480 St. Mary's church, Beverley, con- dition of stone . . ii. 469 St. Paul's cathedral, condition of stone . . . . ii. 460 Salenia, account of . . i. 480 Salisbury cathedral, stone of . ii. 464 Salt, beds of, in New red sand- stone . . . i. 291 mines of Cheshire . ii. 398 Poland . . ii. 401 Salt-works of Cardona, in the Pyrenees . . ii. 400 Sand, auriferous, of Russia . ii. 281 use of, as a mineral manure ii. 488 Sandstone, recent formations of ii. 1 37 value of, as building material . . ii. 469 rate of decomposition of . ii. 477 VOL. PAGE Sandy soils, not necessarily barren ii. 488 Sanguinolaria compressa . ii. 10 Santee limestone . . ii. 107 Saone and Loire, depart, of, highly inclined seams of coal . ii. 363 Saugur, Tertiaries of . ii. 97 Saurians of the Magnesian lime- stone . i. 282 New red sand- stone . i. 303 Lias . i. 340 Oolites . i. 404 Wealden . i. 436 Cretaceous pe- riod . i. 487 European Terti- aries . ii. 77 - Asiatic Terti- aries . ii. 100 Sauroid fishes i. 278 Saw-fish of the London clay . ii. 76 Saoncava rugosa . . ii. 18 Saxon Switzerland, Geology of i- 462 Saxony, mining laws of . ii. 426 Scaglia . . . . i. 467 Scalaria similis . ii. 1 8 Scales of fish, Agassiz's method of classification by means of . i. 183 Scandinavia, mines of . ii. 267 Scaphites cequalis . . i. 483 Scar limestone . . i. 21 1 Scelidotherium . . . ii. 159 Scoresby, Dr., his account of ice- bergs . . . i. 11 Scotch Carboniferous system i. 214 coal-fields, produce of ii. 326 methods of work- ing . ii. 361 Scotland, Old red sandstone of i. 151 building-stone of . ii. 470 , Oolitic rocks of . i. 369 Wealden beds of . i. 428 Tertiary beds of . ii. 20 gneissic rocks of . ii. 1 90 566 GENERAL INDEX. VOL. PAGE Scotland, granite of . . ii. 1 82 Scripture, language of, in refe- rence to Geology . ii. 538 Scyphia articulata . . i. 365 Sections, Geological, their use i. 45 of Railway cuttings ii. 448 Sedgwick, Prof., his account of the Cumbrian and Cam- brian systems . i. 95 his remarks on slaty struc- ture . . . ii. 199 Sedgwick and Murchison, their es- tablishment of the Devonian system . . . i. 156 Sedgwick and Murchison on the Old red sandstone of Scotland i. 151 Selenite very abundant at Mont- martre ii. 406 Semiophorus velicans . . ii. 72 Septaria . . . ii. 13, 29 Serpent, fossil, of the London clay ii. 78 Serpentine . . . ii. 185 Sewalik Hills, Geology of the ii. 94 Shafts, definition of . . ii. 288 method of sinking ii. 290, 338 section of,for a coal-mine ii. 338 Shark tribe, their remains common in the London clay . ii. 74 teeth of, in chalk . i. 487 Sharpe, Mr., his account of the Geology of Lisbon . ii. 40 Sheerness, Artesian well at . ii. 526 Shelly Oolites, value of, as building- stones . . . ii. 456 limestones, rate of decom- position of . ii. 477 Sheppey, Isle of, London clay beds . . . ii. 14 fossil fruits of . ii. 53 Sherringham, rapid degradation of the cliff there . . . i. 13 Shoding, a method of trial for a mineral lode . . ii. 283 Shoots, a particular form of mineral veins . ii. 248 VOL. PAGE Shrewsbury, coal field near . i. 207 Sicilian Tertiary beds . ii. 44 Sigittaria? i. 256 account of . i. 260 Silesia, Silurian rocks of . i. 1 1 7 Silex, a necessary ingredient in soils ii. 482 Siliceous limestone ofChilmark ii. 464 Silurian, meaning of the term in Geology . . i. ' 99 system, establishment of the . . . i. 100 rocks, foreign . i. 1 14 Silver, separation of, from lead ores ii. 310 American ores of . ii. 315 quantity obtained from one vein ii. 316 preparation of the ores of ii. 318 Simeto river, effect of its current i. 12 Siphon, explanation of the action of the - . . . ii. 518 Siplumia, account of . i. 477 pyriformis . .' i. 475 Siphuncle, nature and use of . i. 141 Sivatherium giganteum (head) ii. 102 Skaptaa Jokul, eruption of . i. 19 Skiddaw granite, a starting point for English Geology, i. 95 view of . . ii. 1 95 Skull-cap, a variety of Portland stone . . . . ii. 457 Skye, Isle of, Wealden beds i. 428 Slates of Cumberland i. 96 ; ii. 195 414 Cornwall . ii. 196, 412 North Wales . ii. 195, 413 Scotland . . ii. 412 Slickensides . . i. 36. ii. 308 Slides, a particular kind of veins ii. 255 Slips or faults of strata . . i. 36 danger of, in foundations ii. 451 Slope in embankments and cut- tings . . . ii. 442 of a mineral vein . ii. 250 Sloth, habits of the . . ii. 159 GENERAL INDEX. 567 VOL. PAGE Smawse, quarries of Magnesian limestone at ... ii. 468 Smith, William, his application of Geology to draining . ii. 505 Smyrna, hippurite limestone of i. 466 Eocene beds of . ii. 32 section near . ii. 88 Snowdon, slates of . . i. 105 Soils, mineral composition of ii. 482 Solnhofen, section near . i. 378 Sopwith, Mr. his account of the Museum of Economic Geo- logy ii. 242 South America, Tertiary beds ii. 110 mines of . ii. 268 Shields Committee, con- cerning accidents in mines ii. 386 Staffordshire, coal-field of i. 206 Wales, highly inclined coal seams of . . ii. 361 Welsh coal-field . . i. 203 produce of ii. 326 Southwell Church, condition of ii. 466 Spain, south of, Tertiary beds ii. 40 mines of . . ii. 265 Spamodus micracanthus . ii. 70 Spatangus (Disaster) carinatus i. 393 Species extinct, distribution of i. 81 Speeton clay . . . i. 452 Sphenopteris polypTiylla . i. 245 Spirifer, account of . . i. 273 fragilis . . i. 296 striatus . . . i- 274 verrucosus . . i. 320 Spirolinites . . . . i. 478 Split veins, ground plan of . ii. 247 Sponge, nature of . . . i. 70 structure of . . i. 473 Springs, land . . . ii. 511 on a line of fault . ii. 513 thermal and mineral ii. 513 intermittent . ii. 518 Squaloid fish, in Tertiary beds ii. 74 Stackpole rock, near Tenby ii. 224 Staffordshire, South, coal-field i. 260 VOL. PAGE Staffordshire, South, Northern por- tion of the coal-field i. 207 method of work- ing coal in ii. 347 produce of coal- field . ii. 326 quarries of New red sandstone in ii. 474 Standard air-courses in a mine ii. 351 Stanniferous gravel of Cornwall ii. 282 Star-fishes of the chalk . i. 480 Steel-mill, invention of, for light- ing mines ii. 367 Steep face of coal, contrivance for working . . . ii. 362 Steeple Ashton, coral rag of . i. 364 Steneosaurus, account of . i. 407 Stentings, meaning of . . ii. 354 Stenton stone quarries, Durham ii. 473 Steppes of Russia, erratic blocks on .... ii. 123 Stigmaria ficoides . . i. 260 Stinkstein i. 243 Stirlingshire, 0. red sandstone of ii. 470 Stock-work, definition of . ii. 249 Stones, building, relative value of . . . . ii. 452, 478 Stonesfield slate . i. 359 ; ii. 415 Stoppings, in a coal-mine . ii. 354 Strata, mineral composition of i. 28 drainage of . . ii. 505 Stratification, nature of . i. 5, 30 its use in natural draining . ii. 497 Stratified rocks, formation of i. 6 Stream-works, nature of . ii. 281 Strep tospondylus, account of i. 406 Striated and polished rocks ii. 132 Strickland, Mr., his account of the Geology of the Thracian Bosphorus . . . i. 119 Strigocephalus limestone . i. 165 burtini . i. 166 Strike, meaning of the term in Geology . . . . i. 31 568 GENERAL INDEX. VOL. PAGE Strings in a mineral vein . ii. 249 Stromatopora concentrica . i. 126 Strombus ornatus . . ii. 25 Structure, first examination of, in the earth's crust i. 5 its relation to the habits of animals .' i. 74 of coal . . i. 246 of minerals . ii. 177 Styria, Basin of . . ii. 39 Sub-Apennine strata . . ii. 42 Sublimation, theory of . ii. 274 Submarine forests . i. 23 ; ii. 21 Subsoil, definition of . . ii. 483 Subterranean disturbances, as- sumed cause of i. 34 drainage . ii. 507 Suchosaurus, account of . i. 437 Suffolk Crag . . . ii. 16 Sulphuretted hydrogen gas in coal- mines . . . ii. 373 Sumbawa, volcanic eruption at i. 18 Sump .... ii. 293 Surface draining . . ii. 498 Survey, Ordnance Geological ii. 237 Surveyors, advantage of a know- ledge of Geology to them . ii. 494 Sussex marble . . i. 427 Sweden, gravel of . . ii. 123 Switzerland, Miocene beds of ii. 35 Syenite .... ii. 179 Syme, Gulf of . . i. 467 Synclinal axis . i. 35 Syracuse, section near . . ii. 44 Systems of veins in Cornwall, ii. 254 T. Technical language of Geology i. 26 Teesdale, description of . ii. 263 Teleosaurus, account of . i. 406 Tellina crassa . . . ii. 18 Temperature of deep mines . ii. 294 of mineral springs ii. 513 of Artesian wells ii. 528 VOL. PAGE Terebratula aculeata . . i. 296 navicula . . i. 110 plicatilis . i. 455 reticularis (Atrypa af- finis) . . i. 134 subserrata . i. 320 vulgaris, var. elon- gata . . i. 296 Teredo, perforations of chalk by i. 472 Tertiary strata, classification of ii. 1 of the British Isles ii. 10 of Europe, Older ii. 22 Middle ii. 33 Newer ii. 42 Fossil plants and inverte- brata ih 51 Fossil ver- tebrata ii. 70 of Asia * . ii. 87 of America . ii. 105 building materials of . ii. 476 agricultural charac- ter of . . ii. 492 Texture of soils . . ii. 486 Thames, springs in the valley of ii. 512 Theories of the filling of mineral veins . . . . ii. 274 Theories, Geological . ii. 229, 533 Thermal springs . . . ii. 513 Thick beds of coral . i. 206 ; ii. 348 Thickness of mineral veins, its in- fluence on their value . ii. 252 Thracian Bosphorus, Silurian rocks of .... i. 119 Threads, thin portions of mineral veins . . . ii. 251 Tierra del Fuego, Silurian rocks of .... i. 120 Tiger, fossil species, of the caverns . . . . ii. 144 Tilestone, . . i, 147 ; ii. 415 Tilgate Forest, beds of . i. 452 Till, Valley of the Clyde . ii. 20 GENERAL INDEX. 569 VOL. PAGE Timber used in the Cornish mines ii. 296 Time, necessary for the production of geological phenomena . i. 50 Tin, stream works, of Banca ii. 281 ore, preparation of . ii. 306 Tintagel, slates of . . ii. 412 T intern Abbey, stone and condi- tion of . . . ii. 471 Toadstone of Derbyshire . ii. 215 Tomb-stones useful in the selec- tion of building-stones . ii. 452 Top-cap, a variety of Portland stone . . . . ii. 457 Torghal, pierced rock at . ii. 523 Tortoise, gigantic species of . ii. 99 Totternhoe, building-stone of ii. 455 Touraine, Miocene beds of . ii. 34 Towey, slate on the banks of ii. 198 Toxodon, account of . ii. 152 Trachyte . . . ii. 184, 217 Transition rocks, see Palaeozoic. Trap, meaning of the term . ii. 1 75 junction of, -with stratified rocks . . . ii. 176 bursting through sand- stone . . ii. 176 dykes ii. 216 Trap-doors in coal-mines . ii. 349 Tree ferns, account of . i. 254, 266 Tree, fossil, in New red sand- stone of Warwickshire . i. 312 Tresavean mine, depth of . ii. 293 Triassic system . . i. 288 Tricarpellites communis . ii. 54 Trichinopoly and Verdichellum, fossils from . . i. 430, 470 Trigonia costata . . . i. 362 Trilobites . i. 128, 176 Triloculina trigonula . ii. 63 Tripoli, composition of . . ii. 60 Trochotoma sulcata . . i. 383 Trochus cingulatus . . ii. 43 Trogontherium . . ii. 86 Trough, meaning of in Geology i. 35 Tubbing, metal, explanation of ii. 338 VOL. II. VOL. PAGE Tubulipora? . . . ii. 18 Tufa ...;.... ii. 217 Tunicata, description of . i. 68 Tunnelling influenced by geolo- gical structure . . ii. 443 Turin, Miocene beds of . ii. 35 Turrilites costatus . . i. 483 Turritella imbricataria . . ii. 10 Turtles, marine, of the Cretaceous period i. 489 Turtles, fossil of London clay ii. 78 Tuyeres or Twyeres, use of . ii. 395 Tyne Valley, description of . ii. 264 U. Ulverstone, haematite of . . ii. 313 Unconformable stratification . i. 32 Underclay in coal-mines . i. 263 Underground work of a mine ii. 294 Underlie of a vein, definition of ii. 250 Unguiculata and Ungulata . i. 60 Ungulata, subdivisions of . i. 64 Uniformity of direction of mineral veins . . . . ii. 272 United States, gold region of ii. 270 Univalves fossil, of the Older Pa- laeozoic period i. 1 35 of the Devonian rocks . i. 177 of the Carboni- ferous rocks i. 274 of the Oolites i. 397 Unstratified rocks rarely used for building purposes . . ii. 479 Upper Ludlow rock i. 110 New red sandstone . i. 289 Greensand . . i. 453 Ural chain, Silurian rocks of . i. 1 1 8 Devonian rocks of i. 171 mines of . ii. 267 Ursus spelasus (skull) . . ii. 142 Uses of Geology. . . ii. 240 2 P 570 GENERAL INDEX. V. VOL. PAGE Vaginula daudini . . ii. 35 Val di Noto, limestone of . ii. 46 Valley of denudation . . i. 37 elevation . i. 37 Valleys, different kinds of, for obtaining coal . . . ii. 332 Valuation of land, advantage of a knowledge of Geology in the ii. 494 Vanning the ores of tin . ii. 306 Vans of Caermarthen and Brecon i. 149 Vaucluse, fountain of . . ii. 523 Vegetable origin of coal . i. 246 Vegetables, parts of, usually found fossil . . . . i. 247 Veins, crossing one another . ii. 244 mineral, definition of . ii. 246 different names of ii. 248 richer when there is a change of ground ii. 253 uniform direction of, in the same dis- trict . . ii. 254 more recent than the rocks containing them . ii. 257 distribution of . ii. 262 theories of . ii. 274 Veinstone, nature of . . ii. 251 Velay, Freshwater beds of . ii. 30 Venericardia cor-avium . ii. 25 scalaris . ii. 18 Venetian Alps, curved strata of limestone . . . ii. 230 Ventilation of mines . ii. 295 coal-mines . ii. 341 the only principle of safety in coal-mines . ii. 369, 388 Ventriculites, account of . i. 476 radiate . i. 475 Venus turgidula . . ii. 25 Verdichellum and Pondicherry, fossils of . . . i. 430, 470 Vermuyden, Col., his method of draining the English fens . ii. 500 VOL. PAGE Vertebrata, arrangement of . i. 58 Vesuvius, eruptions of . i. 18 Veta Madre, the largest mineral vein worked . . . ii. 248 Vicenza, Eocene beds of . ii. 32 Vienna, Basin of . . ii. 39 Viewer, his office in a coal-mine ii. 357 Vincularia, penlagona . ii. 63 Virginia, Oolitic coal of . ii. 329 Tertiary beds of ii. 106 Volcanic rocks of Italy, alum- stone of . . ii. 408 district of the Rhine ii. 209 Auvergne ii. 210 Catalonia ii. 211 Asia Minor ii. 211 action in the vicinity of hot-springs . ii. 514 Volcanoes and Volcanic action i. 15 Volcanoes, great eruptions of . i. 17 18, 19 extinct . . ii. 208 Volhynia, Miocene beds of . ii. 40 Volterra, Alabaster of . . ii. 407 Valuta lamberti . . ii. 18 ludator . . ii. 1 Von Roemer's account of the Wealden beds of Germany i. 428 Vosges, gres de . i. 242, 294 section from Nancy to i. 293 mining district of the ii. 264 Vulturine bird of the London clay . . . . ii. 79 W. Wales, North, Silurian rocks of i. Ill Old red sandstone of . . i. 150 slate quarries of ii. 413 South, coal-field of i. 203 ; ii. 325 iron district of ii. 391 Walls of a vein . ii. 250 GENERAL INDEX. 571 VOL. PAGE Walls-end Colliery, standard air- courses of ii. 35 1 fiery seam of ii. 371 accident in ii. 374 Wardour, Vale of . i. 423, 452 Warwickshire, fossil tree in New red sandstone . . i. 312 Wash, the condition of the . ii. 499 Waste of coal in England . ii. 326 Waste, the unventilated part of a coal-mine ii. 349 Wastemen, their duties in the mine . . . . ii. 357 Water, its power of transporting heavy rocks . i. 9 incursion of in shafts ii. 338 accidents from, in mines ii. 384 extensive reservoirs of, in limestone rocks . ii. 524 Watson's patent drainage pipes ii. 441, 508 Watt, Mr. Gregory, his experi- ment on the nature of basalt ii. 205 Wavellite . . . i. 201 Weald, section across the . i. 46 clay i. 426 Wealden formation, rocks of . i. 420 fossils of i. 431 district, elevation of ii. 223 strata, generally poor land . . ii. 492 Weardale, description of . ii. 263 Weight, its relative meaning i. 9 Wells, natural, in gravel . ii. 512 Artesian . . . ii. 520 Wells Cathedral, stone of . ii. 462 Wenlock limestone . . i. 107 " shale . . i. 108 Werner's theory of the filling of mineral veins . ii. 274 remarks on mining re- cords . . ii. 430 Westminster Abbey, condition of Henry the VIPs Chapel ii. 462 Westminster Hall, stone of . ii. 468 Westphalia, grauwacke of . i. 115 VOL. PAGE Westphalia, Devonian rocks of i. 165 Carboniferous rocks i. 219 Wetherellia variabilis . ii. 54 Wetterhorn, view of . . ii. 219 Whim, description of . ii. 301 Whinstone, a good road material ii. 445 Whitby, Lias of . . . i. 316 alum shale of i. 316 ; ii. 408 building-stone of . ii. 475 Abbey, condition of ii. 475 Whitehaven Colliery, accident from water in . . ii. 384 Whitley's Agricultural Geology ii. 484 Wieliczka, salt mines of ii. 40, 401 Wight, Isle of, Wealden beds i. 426 Lower Greensand of . . i. 449 Tertiary basin ii. 12 Wilton, salt mine of ' . ii. 400 Winning headway . . ii. 340 Winzes, or underground shafts ii. 288 Wolf, fossil species of . ii. 144 Woolhope, valley of elevation of i. 106 Worcestershire and Cheshire, salt works of . . . . ii. 398 Working tools of the collier, ii. 359 Wrath, Cape, gneiss and granite veins of ... ii. 191 Wye, Banks of, conglomerate of the Old red sandstone , i. 149 X. Xanthidium, description of . i. 478 Y. Yoredale rocks . . i. 211 York Minster, condition of the stone . . . . ii. 468 Yorkshire coal-field. . i. 210 " method of working coal ii. 346 572 GENERAL INDEX. VOL. PAGE Yorkshire Coast, Lias of . i. 316 Cretaceous rocks of . i. 452 Tertiary strata of ii. 19 Z. Zamites . . i. 387 Zanclus .... Zante, Island of, Miocene beds Pliocene beds Zechstein Zeuglodon, description of Zinc, ores of . Zinnwald, vein of Zoology, necessary in the study of Geology i. 1 classification of . , i. 56 VOL. PAGE . ii. 73 ii. 41 ii. 47 i. 243 ii. 114 ii. 311 ii. 266 ERRATA TO VOL. I. Page 128, line 3 from top, for GRAPOLITES read GRAPTOLITES. 296, note, line 3, arculata aculeata. 320, 6, colabratus coluhratus. 355, line 16, Dr. Urville D'Urville. 497, note, p. 2 p. 130. 498, last line p. 45. p. 175. VOL. II. Page 63, references to figure, for g. Polymorphina read g. Cristellaria. h. Frondiculina h. Polymorphina. 99, line 1 7, for twenty read twelve. 480, last line, for ST. HELEN'S BAY read ST. 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