Journal of the Society of Arts, Announcements by the Council. ORDINARY MEETINGS. ... ... 286 ... 286 netic iron ores, specular iron ore, red hæmatite, and micaceous iron, and numerous hydrates, called brown hæmatites. There are also spathic iron, brown spar, and clay ironstone. Silicates and phosphates of iron are also sometimes used. The richest ores are the protoxides; the next the peroxides; and the least rich, but most abundant, the carbonates, or rather the carbonates of the oxide. The phosphates are sometimes rich in iron, and the silicates also. The former are chiefly worked in Canada; the latter near St. Maurice, and in the Canton of the Valais, in Switzerland. The sulphides are valued only for the sulphur they contain. Magnetic iron ore is MARCH 29.-"On Window Horticulture, and the Cul-a rare mineral in England. It is diffused in the old rocks, tivation of Plants and Flowers in Cities and Crowded but is not abundant. The chief supplies are from NorLocalities." By JOHN BELL, Esq. Wednesday Evenings at 8 o'clock. CANTOR LECTURES. The concluding lecture of the Second Course, the subject being "The Applications of Geology to the Arts and Manufactures," by Professor D. T. ANSTED, M.A., F.R.S., will be delivered on Monday evening, at Eight o'clock, as follows:— MARCH 13TH.-LECTURE 6.-On Metalliferous Veins or Lodes and their Contents, and on the Extraction of Metalliferous Minerals from Lodes. These Lectures are free to Members (without ticket), and every Member has the privilege of admitting ONE Friend to each Lecture. Proceedings of the Society. CANTOR LECTURES. way, Sweden, and Russia. The central portion of the island of Elba is of this material. Important veins of it exist in India and the East, in North America, in Mexico and in Brazil. It contains, when pure, 72 per cent. of iron. The hæmatites are more common with us than magnetic ore. They are rich in iron, but it is more profitable to mix them with the poorer ores than to use them alone. There are two kinds; one yielding, theoretically, 69 per cent. of iron, and the other 56 per cent. The ores are rarely free from foreign substances. The crystalline are either specular ores, micaceous ores, or oligist. The earthy ores are opaque and red, whence the name "hæmatite," or blood-stone; but when containing water, this colour passes into brown. They are valuable for smelting. They are also used for polishing; and some varieties are employed as pigments. The carbonates of iron, yielding from 20 to 45 per cent. of metallic iron, are sometimes crystalline, as in sparry iron, but more often earthy, as in the common ores of most parts of England. They form the group of clay ironstones. The chief mines of hæmatite in England are at Ulverston and the neighbourhood of Whitehaven, at the bottom of the limestone in contact with slate. At Todholes, near Cleator, this SECOND COURSE.-FIFTH LECTURE.-MONDAY, MAR. 6. ore is worked as a quarry. The floor of the deposit is a IRONSTONE AND COAL. Professor ANSTED first pointed out that iron and coal were the chief sources of material wealth, and that Great Britain was especially provided with these minerals. The circumstances under which iron ores and mineral fuel are found, the extent of the deposits, and the way in which they may be obtained, were the subjects to which he would now direct the attention of his audience. Iron is widely disseminated, and forms part of almost every substance with which we have to do. But although thus common, the ores are not universal. In most of them iron is in combination with oxygen. These include mag white and red mottled shale of the limestone series, almost a fire-clay, and 40 feet thick. The surface of the shale is uneven, and is covered by white quartz pebbles. Then comes a magnificent bed of hæmatite, from 15 to 30 feet thick (sometimes as much as 60 feet), subdivided by irregular joints. Bands of greenish-black shale are interstratified with this ore. It is difficult to say whether the ore is a contemporaneous deposit. It is extracted in the manner adopted in the case of coal, and the quantity removed is large. Besides these mines, the same ore has long been worked from the carboniferous limestone of Low Furness, in a deposit resembling a chasm or vein, and at Dalton, under similar circumstances. Curious dish shaped deposits of hæmatite exist in the same neighbour raised with the coal. The system of bell pits is adopted hood. Some of these are 50 yards in width, and where the ironstone nodules of the lower coal measures 20 yards deep. The ore in them is only covered come close to the surface. There are small shafts by drift. The ore is fine and crystalline. From arranged in great numbers on the line of strike at a disone point you may proceed 400 to 500 feet in either tance of a few yards from each other, and in the Forest of direction in one solid mass of this valuable sub- Dean the ore lies in open spaces in the limestone, called Other stance, and its bottom has not been reached. "churns," or 46 pockets." In mining it is cut away, hæmatites are from Derbyshire, the forest of Dean, leaving natural pillars. The contents of the deposits Somersetshire, and South Wales. Those of the forest of vary, both in quality and quantity, and the result is a Dean seem almost inexhaustible. The coal measures are picturesque irregularity, strongly contrasting with the equally rich in clayey iron ores. They are impure, monotonous galleries of coal mines. To utilise the poorer earthy, and carbonaceous minerals, among which iron ores of iron, admixture of other mineral is needed in the oxide is present to a large extent. The clay ironstones furnace. This is called a flux. With the common ores are black, blackish-brown, yellowish-brown, pale yellow limestone is a flux. The richer ores can be reduced at or drab. They are sometimes regular bands and some-once with charcoal in small quantities; the great operatimes groups of nodules alternating with coal bearing tions of iron smelting are confined to those countries deposits. In the Bradford districts (Yorkshire) there are where the claystones and limestone abound, and where groups of bands near the bottom of the coal measures: there is also an abundant and cheap supply of mineral the upper group contains five bands, which are valuable fuel. Everything thus resolves itself into a question of though not pure. They contain 36 per cent. iron oxide coal. Where there is coal other things are at hand. When and 25 per cent. carbonic acid, besides nearly 20 per cent. coal is absent other mineral wealth is comparatively useof silica. In Derbyshire the ironstones are numerous, and less. Too much attention cannot be given to the history of they yield from two to six thousand tons per acre. The mineral fuel, that we may know where to expect deposits most remarkable is the "Black shale," of Stavely, near and how to obtain them. There are many varieties of Chesterfield. It consists of two groups: the upper con- mineral fuel differing in their properties and in the circumtaining nine, the lower twelve seams, half an inch to stances of their occurrence. I do not include among coal 14in. in thickness. The Shropshire and North Stafford- the shales which simulate coals, and are sometimes reckoned shire coal-fields yield some excellent qualities of ore as part of them, but only the coals strictly so called, adapted for making the best kinds of iron, but the quan- namely, the anthracitic and bituminous varieties and tity per acre is not large, nor are the ironstones rich. lignites or brown coal. Some have no value for comIn the Potteries coal-field the ironstone bands are in the mercial purposes, but their carbon contents are all strongly upper part of the field, agreeing with South Staffordshire marked, and the carbonates afford the best measure of and North Wales. The ironstones of these districts include their relative practical utility. Lignites are inferior to the black bands, originally worked in Scotland. In South coals. They are irregularly distributed in rocks of the Wales, the coal measures form two series, the lower con- tertiary period. They are so far altered as to have a taining the great bulk of the iron bands. These may be mineral aspect, but they retain a woody character. They followed across the Bristol Channel to Ireland, but are exist sometimes in masses of enormous dimensions, but there poorer than in Wales, yielding an average of less not in regular beds. In England they have no value, but than 20 per cent. Scotland is exceedingly rich in similar in Germany there are important deposits. This kind of ores. Within a few years enormous deposits of iron ore fuel labours under a great disadvantage. It contains have been obtained from the Cleveland Hills, in the east water (at least 10 per cent.), which only is got rid of by of Yorkshire. On the coast there crops out a thickness of drying in the air. Lignites contain much ash. Thus, fifteen feet of ironstone, containing an average of 30 per when burnt, much of the heat is left in the conversion cent. of metallic iron, but, unlike an ore, resembling an of the contained water into steam; and part is wasted on irony sandstone, its surface deeply rusted. It occupies the the ash. But lignites are not to be despised as fuel. position of the marlstone in the middle of the lias forma- They have been found available for manufacturing purtion, and extends over a region of some hundreds of poses, for iron smelting, for railways, and for steam-boats. square miles, thinning out towards the south. The In the valley of the Rhine, on the shores of the Baltic, supply must be regarded as practically indefinite, and and in Styria, are some of the thickest of these deposits, it is obtained with extreme facility. Its yield at one approaching 200 feet in thickness. The very best lignites point near Eston, has averaged 50,000 tons per acre. may be detected on exposure. After a short time they and the available ore per acre would average 40,000 tons, change, and in a few months fall to powder. They must yielding 10,000 tons of metallic iron. In France, also, thus be brought into use immediately after coming out of the oolitic rocks are partly made up of rich ores and of the mine. Most of the newer deposits of mineral fuel are iron, the ores being earthy and not easily recognised, lignites. The exact reason of this is not clear. It was except by those who trust to analysis instead of ap- long regarded as an axiom in geology, that no coals were pearance. The value of such ores is about equal to that deserving of the name but the carboniferous period. of English oolitic ores, the general average being about Real coal exists, however, not only in secondary 30 per cent. The most remarkable beds of ore are in the rocks, but in tertiaries. This is proved by the contents centre of France, not far from coal. Belgium and Ger- of a remarkable coal-field in the valley of the Zsil, in many are not less rich in valuable ores than France; but Transylvania. There, in tertiary sands, are regular seams they are not always available for the manufacture of iron, of excellent coal, very thick, and standing every test. as, without fuel, the richest iron ores are of little value. Chalk, the oolites, and the lias also contain coal. In The value of ironstone depends much on the supply of England the Kimmeridge coal is a rich bituminous shale. fuel at hand, and thus the ironstones of the coal measures, The Brora field possesses two seams, worked by pits sunk though not rich, are important; while it is only from 80 or 100 yards. The coal is bituminous, and burns to accident that other ores possess the value now attributed a white ash. The Whitby coal has been worked more to them. In the north of Europe, where there are forests, than a century, and is of fair quality. There is excellent and cheap labour, charcoal iron may be made of the pure oolitie coal' on the Danube. One deposit is at Fünfores of these countries; and in India, smelting can be kirchen, not far from Pesth. Though poor in appearance, carried on to advantage in small furnaces, but these are and powdery, this coal burns well, with flame and much exceptional conditions. The methods of obtaining iron heat and without much ash. The Ovavi za coal is inore vary according to the position of the ore, the magni ferior to the Fünfkirchen, but supplies the Vienna and tude of the deposit, and the presence of other useful Basiasch railroads. Asiatic coals are chiefly from colitic minerals. In the lias and oolites, the ores are removed rocks. There are five coal districts-three in Northern by digging or quarrying. In the coal measures they are India, one in Cutch, and the fifth on the coast of the Barman empire. The coal is associated with limestones, adjacent, is 100,000 acres. There are seven workable elays, and ironstone bands. The South African coal is from seams, the thickest of which is eight feet. They are rocks of the same age. A large tract in Eastern Virginia worked under considerable difficulties, and at great depths, contains valuable oolitic coal, worked near Richmond. sometimes beneath the sea. The coal is good and caking. There are three seams, one of them 30 or 40 feet thick; The South Lancashire coal-field (4) supplies the vast the total thickness about 30 feet. The coal is adapted to population concerned in the manufactures carried on in the manufacture of gas, but varies in different parts of that part of the kingdom. The coal occupies an irregular the field. The great coal fields of England, of Belgium, area. It is found not only in the coal measures, but in of Spain, of France, and of North America, besides those the millstone grit, and the whole area includes a thousand of Bohemia, Moravia, and the Rhine, of Russia and China, square miles of strata. Many of the coals are thin, and and probably of Australia, belong to the Paleozoic rocks. the sections are unequal. In one direction there are 75 The coal-fields of Great Britain range from Somersetshire, beds of coal in 2,000 yards of measures, the total thickness in the south, to Ayrshire, Lanarkshire, and Fifeshire, in of coal being 150 feet. In another direction there are Scotland, in the North. There are four principal groups only 26 seams, though the total thickness of coal is 90 of deposits, distinguished as the Northern, Eastern, feet. The thickest bed is ten feet. The quality is good. Western, and Southern. These again are subdivided, There is excellent cannel worked near Wigan and elseand we have, in a different order, the following coal- where, particularly valuable for gas. The available coal fields: (1) the Newcastle coal-field, (2) the Cumberland has been estimated at 4,000,000,000 tons, but the evidence and Westmoreland coal-fields, (3) those in the West is very imperfect. The sinkings are not deep, and the Riding of York, (4) the South Lancashire coal-field, (5) | quantity of water is not excessive. The Flintshire and the Flintshire coal-field, (6) the great Yorkshire and Denbighshire coal-field (5) is smaller and much worked. Derbyshire coal-fields, (7) the North Staffordshire, (8) There are five workable seams, of which one is nine feet the Coalbrook Dale and other Shropshire coal fields, (9) thick. The total thickness of coal is nearly 40 feet. the Worcestershire coal fields, (10) the Leicestershire, Among the beds is a cannel, called curly cannel, ex(11) the Warwickshire, (12) the South Staffordshire, (13) tremely rich in hydrocarbons. The Yorkshire coal-field the Forest of Dean, (14) the British and Gloucestershire (6) supplies, many large towns in the north of England. group, (15) the South Welch coal-field. In Scotland, in The number of seams is not large, but one of them is ten the valley extending from the Firth of Forth to the feet thick. and there more than thirty feet of workable Firth of Clyde, we have (16) the Clyde Basin, (17) the coal. The quality is excellent, and the pits of moderate Ayrshire coal-field, (18) the Lesmahago Basin, (19) the depth. There are also very numerous bands of ironstone. Clackmannan coal-field, (20) the Fifeshire, (21) the The North Staffordshire or Pottery coal-field (7) contains Lothians, and (22) the Dumfries. All supply bituminous a number of good seams of excellent coal. Here there is coal and some also yield cannel coal, steam coal, or forty feet thick of coal, in twenty-four seams, one of anthracite, and all are liable to faults of all degrees of which is ten feet thick. With the coals are ironstones. magnitude, and every variety of condition. The faults are The South Staffordshire coal (12) is brought up by faults sometimes mere interruptions of continuity, but sometimes through the new red sandstone. It has one seam, called wide gaps filled with stones or rubbish. There is no the ten-yard seam," exceptional among the English doubt of the vegetable origin of coal; but it still remains coals. In other countries are many beds of coal that bear a mystery how coal was formed, or what combinations the same proportion to this that the thick coal of Staffordwere necessary to produce it. In most cases it represents shire does to the six-foot coals of Newcastle. The Forest a mass of vegetation that must have taken many years, of Dean has been less worked than some, but is of conor a large area, to accumulate, but yet in some instances siderable importance. Near it, in Gloucestershire, is there is proof that it must have accumulated rapidly. It another small coal-field. Near Bristol there is an extenseem to have accumulated near the mouth of large rivers sive and important coal district, now much worked, and or low swampy flats. Bituminous coal is brittle, burns yielding a large supply of excellent fuel. We come nexg with flame and smoke, and gives off gas on dry distillation. to the great South Welsh coal-field (15), which includet It contains from 10 to 30 per cent. of volatile substances, 900 square miles. It is divided into three unequal parts; and leaves a residue of coke. Caking coal is a variety the west anthracitic, the middle steam coal, and the east which runs together in the fire. Cannel coal, or parrot, bituminous. With the coals is ironstone; generally thin, is compact. does not soil the fingers, and can be sculptured. but of good quality. The thickness of coal is 70 to 100 It burns like a torch or candle, with much light and feet. Although the estimates of the total quantity of coal smoke, and contains from 40 to 60 per cent. of volatile are exaggerated, it is the largest and most important in substances. Steam coal is a hard semi-bituminous coal, the British islands, and its resources will be available long with little volatile matter, but burning freely with flame after the smaller coal areas of the north have been and much heat. Anthracite is free carbon, homogeneous, exhausted or rendered unworkable. The Scotch coaland with conchoidal fracture. Some varieties are powdery fields are both numerous and rich. Most of the coals are or flaky; some resemble graphite. The Newcastle coal-field dry, free burning, but not caking. They belong to the (1) has been the most extensively worked of any. Till lower members of the carboniferous series, and are older lately it yielded bituminous coals and cannel, it now also than the English coals. The total area is 1,600 square vields excellent steam coal. Its coal is valued for house- miles. Coal has been long worked in Scotland, and the hold use, and it makes the finest coke. No anthracite total quantity raised amounts to 12,000,000 tons. An has been found here. The area occupied by coal contains important part of the Scotch coal is made use of for disabout 700 square miles, and is divided by a great fault tillation, to obtain paraffin oils. Ireland has coal-fields, Crossing the whole field from east to west, the strata being both bituminous and anthracitic. The former are small, lowest on the northern side of the fault by ninety fathoms. but the coal is abundant. The anthracitic deposits are There are no important bands of ironstone. There are more numerous and more worked than the bituminous. forty seams in the Newcastle field, but only eighteen are The coal of Munster is the most developed. Belgium is workable. The most valuable is two yards thick. The rich in coal, and the province of Hainault, the western total thickness of workable coal is eighty feet, and the division of the coal-field, is very remarkable. Every mean thickness of workable coal four yards. Some of variety is found there from pure anthracite, burning the best seams are worked out to a considerable depth. without flame, through the rich bituminous kind called Estimating the area of 450.000 acres, the average thick-" Charbon gras," making excellent coke, to the flaming ness at four yards, and the weight of the coal at one ton per cubic yard, the field would contain eight thousand millions of tons of coals. The Whitehaven field yields valuable coal. Its extent, with two other small fields France coal or cannel called " Fléau." The most valuable of all no coal-fields, and contain the same varieties of coal. In the matter of importance to know whereabouts, at what depth eastern part of the country, as at Saarebrück, on the and in what state the coal lies. Where the outcrop i Moselle, there are others of the same nature. In the known, the dip of the coal regular, and the coal interior the most important are in and near the Basin of faulted, this is not a difficult task. But the permanent the Loire. In central Franee there are numerous small inclination of a coal seam is not always the same as it basins, in some of which the thickness of the coal is dip at the outcrop, and faults must not be left out of calextraordinary. At Aubin there are 124 yards of solid culation. Better ground for an opinion than calculation coal in eight seams, one of which measures fifty yards at is therefore necessary, and boring must be resorted to. its outcrop. In Rhenish Prussia the basin of the Ruhr, that we may learn the general relations of the beds and near Dusseldorf, is the seat of important coal mining the depth to a known point in the series, after which ealoperations, and the Saare coal-field extends from France culation is easy. Three borings are necessary where the into Germany. The chief German coal-fields are those coal is not already proved, and its outerop is not clearly of Bohemia and Silesia, Moravia and Galicia. The known. Several are required when there is reason to total yield of bituminous coal from the Austrian empire expect faulted ground. When all is known that can be in 1860 was about one and a-half million tons. Some of made out concerning the circumstances under which the the rivers of Russia, and some localities on the shores of the coal lies in any given property, the next operation is to Black Sea yield good coal. The Iberian peninsula is very rich sink a shaft to intersect the bed at a certain depth, so in coal. In the Asturias, there is a coal area of very large that all that is possible of the coal seams of the district dimensions, containing upwards of a hundred workable may be worked. Great experience is needed to decide seams, varying from three to twelve feet in thickness. this point. On the one hand, if the pits are too deep, In the south of Spain, in Portugal, and near Barcelona, unnecessary expense is incurred, not only at first, but there are workable coal seans. There are coal seams afterwards, in getting as well as reaching the coal, and in almost within the arctic circle. North America contains lifting the water. On the other hand, if they are 80 coal-areas, compared with which the richest deposits of placed as not to be able to remove the coal from the exEurope sink into insignificance. The chief are the coal-tremity of the estate, that portion will be lost; for after field of the Alleghanies, including the basin of the Ohio expensive pits have been sunk, and much of the coal and the coal-field of Illinois, the basin of the Missouri, got, it will not be worth while to get the rest by a and the coal-fields of Nova Scotia, New Brunswick, and fresh sinking. So with regard to faults, if the pits Cape Breton. The Alleghany coal-field measures 750 be sunk without reference to them, great difficulty miles in length with a mean-breadth of 85 miles, and may be experienced and heavy expenses incurred that traverses eight principal States, among which are Virginia, might be avoided by greater knowledge of the ground. Pennsylvania, Ohio, Kentucky, and Alabama. Making a When coal is being got from near the outcrop, it is usual liberal deduction for unproductive portions, denuded to sink many more shafts than when the mine is deep. strata, and unattainable depths, there are 25,000,000 acres The enormous cost of deep shafts justifies this economy, of valuable coal-field. The coal is partly bituminous, but there are both disadvantages and great dangers partly anthracitic, and the seams numerous and convenient. in mines that are carried on by a single shaft or by The Illinois field includes the Indiana district, where a shafts too far apart. In the event of an accident, either rich bituminous coal extends over an area of 8,000 square to the shaft or in the ventilation, communication may be miles. There is another great coal-field in Missouri. entirely cut off, and thus a heavy loss of life may result. British America supplies coal in New Brunswick, Nova Thus the determination as to the number and position of Scotia, and Cape Breton. The New Brunswick beds are the shafts is a matter to be very carefully considered. In thin. Nova Scotia is extremely rich, and contains one shallow mines, the pits are generally single and of seam of thirty-four feet of good coal, besides others of moderate size. In deep mines, they are in pairs, or ordinary proportions. The coal is excellent. South one very large shalf is divided into three portions. A America contains coal on the coast of Brazil. China and shaft or shafts being decided on, the work of sinking Japan possess mineral fuel extending down the eastern commences. The rocks through which the sinking has to side of Australia, where coal has been long worked. pass will some of them be water-bearing beds, and would The Chinese coals were worked at least six centuries ago, supply strong springs, if that were the object of the both anthracitic and bituminous. New Zealand contains sinking. If water is reached while sinking, it must be shut coal. Borneo has large deposits. The methods adopted off; if it come in at the bottom, it must be pumped out. to obtain coal constitute the practice of mining; they vary The only way of shutting it off is by lining the shaft according to the position of the coal, the thickness of the with an iron casing passed down as the sinking proseam, the nature of the rocks above and below, the ceeds. The bottom of the shaft is the coal seam which quality of the coal, and the quantity of gas it gives off under- it is intended to remove. When the coal is reached, and ground. The quantity of water also enters into considera- there are two pits, these are immediately connected, tion. If coal crops out on the side of a valley, it can be got partly for ventilation, and partly for the convenience readily, and at small expense, by levels or galleries of further workings. One pit should be free, and tunnelled into the side of the hill. Coal, however, being serve as a chimney for carrying off the air, which is rarely horizontal, a gallery, following the dip of the coal, injured by the breathing of the men, or by emanawill incline down-hill on one side and up-hill on the other tions of gas from the coal. During the sinking of each side of the valley. In the first case any water that enters pit, if more air is wanted than naturally comes down, will escape, but in the other it will accumulate. The coal the shaft is divided into two portions by a partition, and also can be run out readily in the one, and must be drawn ventilation is effected by artificial means. If there is a up-hill at some expense in the other. Thus, it is only pair of pits close together, they are usually sunk on the when coal is horizontal or dips towards a valley, that line of dip of the beds, so that one shall reach the coal at crop workings can be carried on with advantage. In a greater depth than the other. In this case a natural the other case it will be better to sink a pit and obtain the ventilation sets in, one shaft acting as a chimney to carry coal by running a drift from the bottom of this pit. Crop heated air up, and the other as a pipe down which the workings are confined to the early workings on a seam. heavier air descends. When coal is reached, a drift or Coal at its outcrop may sometimes be obtained by quarry- tunel is carried on it in the direction of the strike. In ing when the seam is thick, and retains its quality as a use- the case of a pair of pits two such drifts are cut, one from ful fuel after long exposure to the weather, but in England each. This enables the field to be laid out conveniently, such workings have long ceased to have much value. and reveals the condition of the coal, tho state of the Among the more remarkable open workings is one at St. roof, and the continuity of the seam. Along these roads Etienne, near Lyons, in France. When underground the coal when removed can be drawn. Along the lower works are to be reached by a pit or shaft, it becomes a drift, or by the side if there is a single pit, the water of the mine is conducted, and when there is a pair of pits, the lower of the two drifts is called the water-gate, and the upper the horse-gate. At right-angles to such drifts, and on the rise of the coal, another gallery is driven, called the winning headway, or, in Yorkshire, the main board-gate. If there be a second shaft at a distance, it is convenient that this should communicate with the winning headway. The further working of the mine may be carried on either by the pillar and stall or the long wall method. The former is adopted in the Newcastle coalfield, and has been introduced with modifications into many other districts. The latter is that followed in the coal fields of Yorkshire. In the Newcastle coal-field, where the coal lies deep, where there is much water, and where shafts are costly, and the coal full of gas, it is found convenient to divide the coal property into a number of panels, or divisions, kept separated by a thickness of forty or fifty yards of coal. Each panel is worked independently, beginning with that most distant from the shaft. Levels are driven at right angles to each other, leaving large pillars of coal to keep up the root, till the whole panel is faid open. When such galleries have been completed the pillars are attacked, carrying away as much as possible, supporting the roof for a time with wooden pillars, and ultimately removing the pillars, and allowing the roof to fall. The farthest panel being removed, the next may be attacked, and so on till the work is completed. In Yorkshire, where the depth is less and the coal harder, with faults less troublesome, the long wall method is adapted. By this, drifts are run through the coal from the main board gate parallel to the winning headway, and the coal is left in a number of long walls supporting the roof. When the mine is thus laid open, the walls are entered by small cross drifts, and the greater part removed, and the roof allowed to fall. In coal mines, there is a cause of difficulty and danger arising from the light carburetted hydrogen gas existing in the coal and emitted under ground, especially where the coal has recently been broken. Besides this fire-damp, choke-damp, or carbonic acid gas, is not unusual. Both have to be provided against by ventilation, and thus the conveyance and distribution of air is essential in laying out a coal mine. Mixed with atmospheric air, this light gas, when exposed to flame, explodes, leaving after explosion carbonic acid gas and a small quantity of water. When a large quantity of gas issues from coal, and mixes with the atmospheric air carried down for ventilation, as soon as the proper mixture is obtained the light from an open candle would explode the whole, leaving behind a poisonous, heavy gas, which must inevitably choke those who have not already suffered by the explosion. By the ventilation of mines, dangerous mixtures of gas should be rendered as unlikely to occur as possible, and, by a safe method of lighting, the danger, when it exis's, should be avoided. fectly safe ventilation and a perfectly safe light are not easy to find, and accidents still occur from neglect of proper precautions. The ventilation of mines is conducted by producing a strong draught up one shaft by means of a fire at the bottom, or by exhausting the air by steam or other means at the top. All the air entering the mine by the other shaft or shafts is forced to take a course through the workings, and along the levels, before reaching the up cast shaft. Extreme care and attention is needed to ensure the ventilation being adapted to the issue of gas, and to avoid a dangerous mixture. But a safety-light is needed, even where the ventilation is most perfect and best looked after. Such a light was provided in the Davy lamp, and it is theoretically perfect if the explosive gas in the mine be light carburetted hydrogen, and if due caution be used. This lamp is a common oil lamp, covered with a metallic gauze, so open that little light is intercepted, but so close that flame cannot pass. The gas poured into a mine from certain kinds of coal, or from empty spaces met in working coal, is sometimes large in quantity, and issues with so much force as to overcome all efforts to render it safe by mixture But per with atmospheric air. In such mines there is a constant FOURTEENTH ORDINARY MEETING. The following candidates were proposed for election as members of the Society : Newcombe, Cornelius Prout, 16, Barnsbury-villas, Liver- The following candidates were balloted for Yardley, Vincent, 3, Thorney-street, Bloomsbury, W.C. The Paper read was ON THE GINNING OF COTTON. It was for a long time the habitual boast of the planters of the Southern States of America that "Cotton was King, that it ruled England, and that they, the planters, ruled cotton." The American civil war itself was in some measure due to this delusion. In renouncing Federal authority the Southern people, then unprepared for war, were almost unanimous in the belief that England would interpose, either by diplomacy or by arms, as might be necessary, to prevent any interruption in her supply of cotton. In 1860, when our total consumption of this great staple was 1.083,000.000 lbs., exceeding that of any previous year, five-sixths of that supply was drawn from America. Last year we consumed but 561,000,000 lbs., or about one-half as much as in 1860, and of this less than one-twelfth was drawn from the once United States. In other words, nineteen-twentieths of the American supply has been lost to us, and with the failure of the recent negotiations for peace and with the certainty of the overthrow of American slavery, no one can pretend to say when any portion of this loss will be recovered. At present the mills of Lancashire are mostly supplied from India, the larger proportion of Indian cotton being grown in the Central and Western provinces, and shipped from |