within the town, the assailants were enabled to enter the latter by surprise. The other kind was executed in a similar manner, and was intended to lay the rampart of the place in ruins; for this purpose, the gallery, having been driven as far as the walls, was carried on to the right and left under the latter, which were supported by props of timber till the time appointed for the assault was come; then, the props being drawn away or consumed by fire, a portion of the rampart fell into the ditch; and the troops, who were kept in readiness, passed over the ruins into the town. Mines of this kind are described in a relation of the siege of the castle of Boves near Amiens, at which siege Philip Augustus attended in person. At the siege of Melun, which was carried on by Henry V., king of England, and the Duke of Burgundy, in the year 1420, the besiegers having driven their mine almost up to the walls, and the besieged having executed a mine in opposition, a barrier was erected where the two galleries met, and there the king and duke fought with lances against two Dauphinois.

As the parties engaged two abreast, it is evident that the galleries must have been a considerable breadth. The old French writers occasionally applied the term mines to what were also then, and are now, called trenches. Thus, at the siege of Harfleur, in 1449, mention is made of broad and deep trenches by which the approach to the wall is said to have been rendered secure; and the same works are immediately afterwards called mines.

Gunpowder was, in 1487, used in military mining by the Genoese at the siege of Serezanella, a town belonging to the Florentines; but on this occasion without success. It is stated, however, in the life of Gonsalvo de Cordova, that Peter of Navarre, a Spanish engineer, formed mines with gunpowder at the siege of Cephalonia, near the end of the 15th century, when the Venetians and Spaniards took the island from the Turks. And in 1503 the same engineer, or, according to Vallière, an Italian called Francis George, succeeded in taking by such a mine the Castle del' Ovo at Naples. This fortress was situated on a rock nearly surrounded by the sea, and had during three years resisted the united arms of the Spaniards and Neapolitans. From that time the practice of forming mines with gunpowder was almost constantly followed in the attack, and after a short time gradually in the defence of fortresses. So powerful was the effect of mines in the attack, that it was not an unusual occurrence for the besiegers after forming their mine to invite the besieged to see it, in order to bring about a surrender without further bloodshed. The besieged from very early times had a gallery placed a short way in advance of the foot of the wall, termed an envelope gallery, to warn them of the operations of the besiegers. From this gallery branches were run out, and used to what was termed "give the camouflet to the enemy's miners;" that is, a small charge was exploded, which, though insufficient to produce any surface effect, destroyed the besieger's gallery and suffocated his miners. From this to the adoption of ordinary mines was a small step. By means of 1173 mines, great and small, the Venetians defended Candia during more than two years (1666 to 1669) against the whole power of the Turks. By mines also, in 1762, the town of Schweidnitz was defended during 63 days by the Austrians against the Prussians. In the course of this last siege two of the mines fired by the besiegers had charges of powder amounting to 5000 lbs. each; and the depth of the charge below the surface of the ground was from 18 to 20 feet.

can render a work impregnable; but as a means of delaying the fall of a work, in fact of restoring as far as science can the equilibrium of attack and defence, it exceeds all the other means at the disposal of the besieged: it to a great extent renders the possession of superior numbers, position and material, on the part of the besieger, nugatory. The onward and irresistible advance of the besieger, rapid above ground, from the nature of the work is, though certain, slow in these underground operations. And he cannot neglect them, If the besieged have countermines the besieger cannot refuse to meet him with the same weapons. As the French engineers Gumpertz and Le Brun say, with respect to this, "The loss of a great number of men, and the dis couragement of the whole besieging force, perhaps even their defection, would inevitably follow such a resolution. When, therefore, the front of attack is countermined, the besieger must call the miners of his army to his aid."

The great difference between civil and military mining is this. In civil mining the operations generally carried on at a great depth are in solid rock, whereas in military mining they are near the surface in soft ground, which requires supporting to prevent its falling in and crushing or stifling the miner. The principal portion of the art of the military miner consists thus in the management of these supports or linings. In permanent systems of countermines, that is, in fortresses furnished with defensive mines as a portion of their defence, the galleries, being made to last for years, are lined with masonry. Many different systems or plans for the arrangement of countermines have been suggested by the different engineers who have written on the subject. These, though varying much in many details having the same object in view, are to a great extent similar. They are disposed over the exposed portions of the front of fortification, and where an enemy would be likely to form his trenches, lodgments, and breaching batteries, that is, round the ravelins under the glacis, and in front of the bastions in the main ditch and also in the rampart. The object to be kept in view is to expose as little as possible of the galleries to the destructive effect of the enemy's mines; hence they should never, if possible, present their sides to the enemy, as the effect of a mine would be not only to destroy the gallery in its neighbourhood, but perhaps to cut off a large portion of uninjured gallery and render it useless for further defence. The galleries must therefore be disposed so as to present their ends to and lie in the direction of the enemy's approach. At the same time they should not be so far apart that the enemy might pass between them without being heard. As the sound of a pickaxe cannot be heard beyond 60 feet underground, from 100 to 120 feet is the greatest distance they should be asunder. And on the other hand they should be close enough for the mines fired in them to cover the intermediate space with their destructive effects without injuring one another. Assuming then that the galleries are 15 feet under ground, which is considered the best depth for defensive purposes, they should for reasons which will appear from the action of the explosion explained further on, be at central intervals of 48 feet.

Space does not permit of our entering further on this subject: the reader is therefore referred to the article 'Mining, Military,' in the Royal Engineer Aide Memoire.' It may be stated, however, that the main gallery which, passing along the counterscarp, serves as the base of the system of mines, is termed the magistral gallery; the advanced galleries are termed listening galleries. If there be an interthose giving access from one to the other, galleries of communication. In offensive mining, the earth is supported by wood-work. There are two different systems of mining, one with what are termed mining frames and sheeting, the other with cases. Mining frames for shafts consist of four pieces, two 4 feet long, and two 3 feet long, about 44 inches by 3 inches thick. The long pieces are made with tenons, which fit into mortices cut in the short pieces, which are further notched to one-third of their thickness; these being fitted together form the frames, which are placed horizontally in the shaft at intervals of 4 feet, and retain the sheeting planks, (which are outside them and prevent the earth falling in,) in their places.

men.

By means of mines in the attack of a fortress, the besieger has a sure and certain method of gradually, it may be slowly or it may be rapidly, according to the ground, appliances, and activity of the enemy, but still a certain and irresistible means of reaching and destroying the defences of the besieged. And this with the loss of comparatively few The successful explosion of a mine by the enemy may destroy a few miners, while an assault costs hundreds or thousands of men. But yet almost every exploded mine is a step in advance for the besieger. Being superior in the field he seizes the crater formed by the explosion, incorporates it in his works, and pushes on from it by fresh galleries. The galleries of both besieger and besieged have been destroyed in the neighbourhood of the crater by the explosion of the mine, whether these were exploded by besieger or besieged. The besieged then pushing on again from his nearest undestroyed gallery, meets the besieger half way, unless, as occasionally happens by skill he circumvents him, but this half way has been a clear loss to the besieged and gain to the besieger. Hence no system of countermines

Gallery frames differ from shaft frames in being composed of only three pieces, two uprights called stanchions, and a top piece called the capsill.

The system of mining with cases is more expeditious than with frames and sheeting; they have long been known as Dutch cases, and were introduced into the British service by General Sir Charles Pasley. They consist of four pieces about 1 foot wide, namely, two stanchions, a capsill, and a groundsill; and for ordinary work are cut out of 2 inch deal. The stanchions have tenons, 2" long by 3" wide, which fit into mortices of corresponding dimensions cut in the end of the capsill and groundsill. These form rectangular cases, which are placed touching one another if the soil is light, no sheeting being employed. The dimensions of the different galleries and branches employed in mining are in the clearHeight.

Width.

1. Used for the descent of ditches and passage of cannon. 2. Used for the passage of troops, two deep.

3. Ordinarily employed for general purposes of attack, giving the miner room to work easily either on both or one knee, and is the most rapidly executed.

4 & 5. Employed for short distances, about 10 or 12 feet only, for placing charges, &c., as being more easily tamped. When cases are used, mines can be driven at nearly twice the rate that they can with frames and sheeting: namely, great galleries and shafts about 1 foot an hour, common galleries about 14 feet an hour.

Ventilation requires to be well looked after in mines, for not only do the gases generated by the explosions of powder collect in the descending and ascending portions of galleries and often stifle the miner, but even under ordinary circumstances the air is so vitiated by respiration that a branch cannot safely be driven more than 60 feet. Hence openings should be made to the surface of the ground, and, if possible, concealed from the enemy, and communications made from adjacent galleries to create a draught. It also often becomes necessary to use artificial means of forcing air down into a mine, by means of a blower or bellows and metal pipes carried to the end of the mine.

The chamber in which the powder is placed is a cubical excavation formed on one side of the gallery, very little larger than is necessary to enable it to receive the box which contains the powder. When this is deposited, the vertical face of the chamber is covered with boards, which are kept in their places by short timbers fixed in horizontal positions between them and the opposite side of the gallery. The latter is then filled up with earth, well rammed, to an extent in the length of the gallery greater than that of what is called the line of least resistance; that is, a line imagined to be drawn from the chamber perpendicularly to the nearest surface where the crater would be formed. The mass of earth thus filling the gallery is called the tamping of the mine. A train of powder in a canvas hose, forming a tube about three-quarters of an inch in diameter, and for security contained in a wooden trough called an auget, or a casing-tube, is laid from the box in the chamber through the tamping to the place where the fire is to be applied; to its extremity is attached a piece of port-fire, which, being lighted, the fire communicates by means of the hose with the powder in the chamber, and an explosion takes place. Mines are also fired by means of what is called Bickford's fuse, which consists of powder encased in a kind of rope made of spun yarn, tarred. This fuse is waterproof, and not so liable to be accidentally ignited, and is especially adapted for damp ground. Electricity is also now constantly employed in firing mines. It was used by the Russians in their mines at Sebastopol, and by the English in the demolition of the docks, &c.

The dimensions of the crater or funnel formed by the explosion depend on the amount of the charge; its form may be considered as an irregular frustum of a cone, or paraboloid, and the mine is denominated one-lined, two-lined, &c., according as the diameter of the crater at the surface of the ground is equal to once, twice, &c., the length of the line of least resistance. Every explosion of this kind necessarily produces a compression of the earth in all directions about the chamber to a certain extent; and the mines formed with high charges have been denominated globes of compression from this circumstance. A line drawn from the chamber to the circumference of the crater, on the ground, is considered as the radius of the globe of compression. The last mentioned description of mine was first employed by Belidor for the purpose of destroying the galleries of the besieger at distances far greater than had before been considered practicable. When a very small, or at least, comparatively to its depth, a very small mine is exploded, no crater is produced, but it is evident that the earth about must be compressed, and galleries, &c., destroyed to a certain distance : the radius of this sphere of compression is termed the radius of rupture. When a crater is produced, the solid compressed will no longer be a spheroid, but an elipsoid, or nearly so, with its major axis passing through the centre of the charge, at right angles to the line of least resistance. With overcharged mines this radius of rupture is greatly increased in fact it is found that with the ordinary or two-lined crater the radius of rupture, or semi-major axis of the ellipsoid, is 17 times the line of least resistance; and the semiminor axis, or extent of compression downwards, is 1-3 times the line of least resistance. With a globe of compression producing a six-lined crater or maximum charged mine, these lines are 4.36 and 1-4 times the line of least resistance. It will be seen that the lateral effect increases much more than the downward effect, as might be imagined. This great lateral effect was employed by Belidor for destroying the galleries of the besieger: such mines are, from the circumstances of the respective cases, perhaps more applicable by the besieger than the besieged.

The rules for determining the charges of mines are founded on the results of experiment, and it is evident that the charges must vary both with the nature of the soil and with the proposed figure of the mine, that is, with the ratio between the diameter of the crater and the length of the line of least resistance. When a mine of the kind called twolined is formed in common earth, the amount of the charge in pounds is considered as very nearly equal to one-tenth of the cube of the line of least resistance in feet; but for a three-lined and a four-lined mine it is supposed that the cube of this line should be multiplied by 21

and by 45 respectively. It is said that Belidor, somewhere about the years 1758 to 1762, fired three charges of 3600 lbs., at a depth of 12 feet, all of which produced craters of 36 feet radius, or six-lined craters. In an experiment made at Potsdam, when a four-lined mine was formed in a sandy soil by the Prussian Major Le Febvre, the cube of the line of least resistance in feet was very nearly equal to the charge in pounds. According to the latest experiments of the French engineers, the charges of powder necessary to remove one cubic yard (English) of material are as follows:

Common earth
Strong sand
Potters' clay
Loose sand
Old masonry
Freestone

In order to determine the proper size of the chamber, or rather of the box, which is to contain the powder, it will be necessary to observe that one pound of gunpowder occupies, in volume, about 30 cubic inches.

Experience has shown that the greater the charge of powder, the greater is the quantity of earth removed by the explosion. But this fact has its limits; for when the charge is considerable, since the whole of the powder does not take fire instantaneously, it will happen that the earth is partially displaced before the inflammation is complete so that fissures being formed in the ground, the force of the powder is spent in the air without producing any effect. Hence it may be concluded that there is a certain charge of powder which will produce a maximum of effect; and it is supposed by Belidor that, in earth of mean tenacity, the greatest craters will have their diameters, at the surface of the ground, equal to about six times the length of the line of least resistance.

MINIATURE. The term miniature would apply with equal propriety to every kind of painting executed on a minute or diminutive scale; but as commonly employed it includes only two, though somewhat widely different, kinds of painting. One of these is that style of ornamental painting, or illuminating, which is seen in its greatest perfection on the vellum pages of medieval bibles, psalters, servicebooks, and other costly manuscripts: the other kind is that of small portraits executed chiefly on ivory, to which indeed the term has in ts popular acceptation been of late years almost exclusively confined.

miniatori in the manuscripts executed by them for noble patrons; and after the decline of the practice of illuminating books, the production of portrait miniatures for placing in lockets, frames, or cabinets, seems to have quickly grown into fashion. Ivory was early adopted as a more suitable ground than vellum for independent works, and its adoption led to a change in the technical processes. In mediæval miniatures, body colours-or colours rendered opaque by the admixture of white-were alone employed, and the ground or vellum was entirely concealed, the brilliancy of effect being obtained by the colours themselves. In modern portrait miniatures, the painters have very generally employed transparent colours, at least for the flesh tints; finding that the peculiar texture and semi-transparency of the ivory by showing through the tints of transparent colours caused them to "bear out," as it is termed, with great brilliancy, besides imparting an exquisite softness, and much of that "inner light" which is so pleasing in carnations.

The ivory for miniatures is cut in very thin sheets, so as to retain as much as possible of its semi-diaphonous character, and when mounted, is" backed" by some perfectly white material. The painting is executed in water-colours, but by a process differing entirely from that known as water-colour painting. Ivory having a smooth and non-absorbent surface, the colour cannot be floated on in washes, or flat tints, laid one over another. The flesh tints and other parts requiring great delicacy of finish, are therefore entirely dotted, stippled, or hatched upon the surface. In the draperies and back-grounds, the colours are however often washed in with flat tints, the inequalities of tint or surface being afterwards got rid of, and the whole worked up by careful stippling. A mezzotinto scraper, and sometimes an engraver's point or needle, is used for removing lights, securing due graduation of tints, &c. Gum is the only vehicle used with the colours besides water. Formerly, it was usual to execute the drapery and background of miniatures in body-colours, but the value of the ivory surface is thus lost, and the brilliancy lessened; while the general balance and harmony are almost always injured by the combination of opaque with transparent colours. The use of opaque colours has therefore been almost entirely abandoned by the best English miniature painters; though retained by French artists, who, it must be confessed, have employed them with great tact and skill.

Until of late years miniatures were almost invariably confined to the face and bust of a figure. They now often comprise the entire person, with all the accessories common to a "whole-length" portrait on canvas, and are painted on a sheet of ivory of a size which almost removes them from the class of minatures. The process is, however, the same in these as in the bust portrait, where the adoption of a larger scale does not call for a somewhat larger handling. Sheets of ivory of sufficient size for these large miniatures-as we must call them for want of a more appropriate term-cannot, of course, be cut from the diameter of an elephant's tusk, as are those for miniatures of the ordinary size. They are, in fact, thin veneers sawn from the circumference of the tooth, as described under IVORY, steamed and flattened under hydraulic pressure, and fastened with a composition of india-rubber to a mahogany panel. Some of these large paintings on ivory, as executed by Mr. Thorburn and others, have a broad and masterly effect; but they are after all hardly to be regarded as miniatures, and certainly do not possess the special characteristics of works of that class. From the nature of the process miniature-painting requires great refinement of taste, dexterity and delicacy of hand, and patience in the artist. It recommends itself by the extreme softness, delicacy, and brilliancy of colour, and the portability and durability of its productions; and it has been pursued with great diligence and success in most countries, but especially in England, France and Italy. From the first the art has been successfully prosecuted in England. It appears to have been introduced by foreigners; but from the time of Nicholas Hilliard, limner to Queen Elizabeth and her successor, who learned the art from Holbein, England has always possessed miniature painters at least on a level with the best of their contemporaries. Among the immediate successors of Hilliard were Isaac and Peter Oliver, from the former of whom, in some respects still unrivalled as a miniature painter, we have portraits of several of the most illustrious of the remarkable men of his time. To them succeeded Alexander Hoskins and Samuel Cooper, and the latter, scarce inferior even to Isaac Oliver, has preserved the best likenesses of several of the most famous of the Commonwealth men, including Oliver Cromwell and John Milton. We need not continue the list: it will be enough to say that, whilst English miniature painters have always occupied a foremost place in their branch of art, it has been admitted even by foreign critics, that the English miniatures of the last and present generation unquestionably take precedence of those of the Continent. But whilst the artists have secured so honourable a position, the art itself appears doomed to give way before the advance of photography, as the miniature painting of the mediævalists did before printing. Some of the best of our living miniature-painters have wholly or in part abandoned the practice of this branch of painting, and others of an inferior order are devoting themselves to painting "photographic miniatures," or miniatures of which the basis is a feebly developed photographic positive. It is however to be hoped that fashion may show sufficient encouragement to the true miniature painter to preserve from decay this delightful branch of art. The practice of painting photographic miniatures

can hardly fail to develope a mechanical mode of painting which can scarcely rank as a fine art, however advantageous the study of photographic portraits may be, as an aid, to the miniature painter.

We cannot refer to a collection of portrait miniatures in either of our national museums; but several private collections have been formed in emulation, and partly from the débris, of the famous Strawberry Hill collection of Horace Walpole. Among the most celebrated are those of the Dukes of Portland, Buccleuch, Hamilton, Marlborough, and Northumberland, which embrace a large number of specimens from the Tudor period downwards. A choice selection from these and other collections was brought together at the Manchester Art Treasures' Exhibition of 1857; and another, but comparatively private exhibition, was made partly from the same collections by the Archæological Institute, London, in the summer of 1860. MINIM, in Music, a character, or note, formed of a round open head, and a stem descending or ascending from its right side—

When first introduced, the minim was the shortest note in music, as its name (from minimus, the least) indicates. It is half as long in duration as the semibreve, and double that of the crotchet. [CROTCHET.]

MINIMS, or MINIMI, also called Pauliners, an order of religious whose asceticism exceeded even that of the Franciscans, of whom they were considered a branch. They were instituted about the year 1436, by Saint Francis de Paula, under the name of Hermits of Saint Francis, and confirmed in 1474 by Sixtus IV. Alexander II. changed the name of the order to that of Minims, as marking the humility of their order. In France they had the name of Bons-hommes; and in Spain that of the Fathers of Victory, in consequence of Ferdinand IV. gaining a victory over the Moors, according to a prediction of Saint Francis de Paula. In Spain a convent of nuns of this order was founded as early as 1495, followed in the course of time by other similar establishments. In France there was no female convent of this order till 1621 when one was established at Abbeville, and another subsequently at Soissons. No house of this order was ever established in England.

MINING. The art of mining embraces the contrivance and management of the operations necessary to effect the various objects requisite in a mine, as the discovery of mineral deposits, the preliminary trials of the value, and the final extraction of their produce by means of suitable excavations and the application of the requisite machinery. These occupations may be said to constitute the business of the miner in the more comprehensive signification of the term, and it will be evident that they demand an extensive range of acquirements in which knowledge, both practical and scientific, must be blended.

History of Mining.—A regular or detailed history of mining, however interesting in itself, would far exceed the limits of this article; we shall therefore briefly glance over some of the most important steps by which mankind have been led to their present bold and extensive operations for the extraction of metals and other mineral substances. The use of the metals, and consequently some process for their extraction and separation, may be traced to the most remote antiquity, and is there lost in the obscurity which veils the early history of our species. Moses ascribes the first use and manufacture of the metals to TubalCain, the seventh in descent from Adam, who is said to have been the "instructor of every artificer in brass and iron." Upon so brief a notice we are not entitled to build much, but it proves nevertheless that the use of the metals is almost coeval with the human race. Profane history likewise shows that it was known to the earliest nations of antiquity, as to the Assyrians, the Greeks, and Egyptians. Gold and silver were abundant among the ancients; an alloy of copper and tin formed the armour and weapons of the Greeks, although iron was not unknown among them, and of this metal the Roman weapons were formed. These facts do not, however, imply any great knowledge of mining, properly so called, as it is well known that metalliferous deposits are often found near the surface, frequently in a state of extreme purity, as gold and copper for example; and in early ages, when they had been so much less ransacked by the miner, these superficial deposits must have been much more abundant than at present, and probably furnished a large proportion of the metallic produce of those times. Most of the mines of antiquity were probably of a similar nature to the stream-works of Cornwall, and it appears from Strabo (175, Casaub.) that the Phoenicians at that early time used to trade to Cornwall for tin and lead. In early times the demand for the metals could not have been very great; their use was then either as instruments of luxury or war, and thus confined to a limited class, so the quantity found near the surface was in all probability fully adequate, leaving but little inducement for deeper and more laborious research.

There is, however, evidence enough to show that operations similar to those of modern mining were carried on by the nations of antiquity. Herodotus (vi. 46, 47) observes that a mountain in the island of Thasos was completely burrowed by the Phoenicians in their search

Strabo speaks of the Cassiterides, which can be no other place than Cornwall or the Scilly Islands; probably the former.

for the precious metals; and the curious fragment of Agatharchides preserved in Diodorus (b. iii. ch. 12, 13) shows that the art of forming shafts and passages for exploring mines and procuring the metals was well known in Egypt. The silver mines of Laurium in Attica were worked by the Athenians, to some extent at least, as early as the beginning of the 4th century B.C. Under the Romans the quicksilver mines of Almaden in Spain, and the lead and iron mines of Sardinia [MERCURY, in NAT. HIST. DIV.], were extensively worked.

It is singular to observe that an art for which this country possesses such great natural facilities, and which was certainly cultivated here both before the Roman conquest and during the Roman occupation of this island, should afterwards have fallen into decay, and indeed for a time have been chiefly practised by foreigners. Prior to the Norman conquest our mines had been much neglected, probably in consequence of incessant civil commotion; and subsequently to this period they were chiefly worked by Jews. In the reign of Elizabeth the art of mining had fallen into so much decay that an importation of foreign skill was found necessary to revive it; and the Germans, long and justly celebrated as skilful miners, received every encouragement to settle in this country and turn their attention to them. From this measure some success appears to have resulted, and in the following reign we find Sir Hugh Middleton, a citizen of London, deeply concerned in the lead and silver mines of Cardiganshire, from which he derived a large revenue, which was expended in that noble work from which the metropolis still benefits-the formation of the New River. About this time a new and important auxiliary was furnished to the art of mining by the application of gunpowder for blasting, which appears to have been first practised in Hungary or Germany; and an invention which had revolutionised the art of war thus became the means of effecting an equally extensive change in one of the most prominent arts of peace.

In the early part of the 18th century another important event took place in the history of English mining. The rich deposits of copper which have long constituted the principal mineral wealth of Cornwall, had up to this time been neglected, partly perhaps from this ore being confounded with "mundic," or worthless iron pyrites, common in most mines, and partly from its lying deeper in the veins than the ores of tin, which had always formed the chief object of search. When at length the nature and value of the Cornish copper ore was fully recognised, a powerful stimulus was given to this new branch of mining, which has been carried on to the present time with great and increasing activity, the copper-mines of that county being now the deepest, the most extensive, and most productive in the world. The great invention of the steam-engine, the progress of which during the last century exercised such vast influence upon our arts and manufactures, was early rendered applicable to mining in this country, and in a great degree contributed to the present perfect state of the art. Savery, who, if we except the somewhat equivocal claims of the Marquis of Worcester to that honour, was the first person who constructed a practically useful engine worked by steam, sought in the first instance the patronage of persons interested in mines, as we see by his publication entitled the Miner's Friend,' in which he describes the nature of his invention and its applicability to draining mines. At this period our mines, although comparatively shallow, were much inconvenienced by water, especially those which were not in situations where hydraulic machines could be employed, and hence the application to them of this new power was at once obvious. The introduction of Savery's engine into our mining districts probably led to the great improvements effected by Newcomen, a resident in Devonshire, which vastly extended its utility, and indeed completely altered its principle. Their conjoined patent was taken out in 1705, and from that date the steam (or rather, atmospheric) engine became a most useful auxiliary in the hands of the miner, and was very generally employed for draining mines, not only in Cornwall, but in the coalmines of Staffordshire and the north of England. The great improvements introduced by Watt in 1765 and succeeding years were quickly appreciated by the mining interest, and his engines were speedily introduced into the mining districts of Cornwall, where they effected a great saving of fuel, and therefore of expense, the coal used in that county being brought from South Wales. It is chiefly to the object of economy that the efforts of late engineers have been directed, and so successfully, that their improvements have fully kept pace with the increasing depth of our mines, many of the most abundant of which would have long since been abandoned had not this been the case. These great improvements have chiefly originated in Cornwall, where ingenuity has been stimulated by the high price of coal; and among the numerous individuals who have contributed to them, the names of Woolf, Trevithick, and Grose may be particularly mentioned.

The improvements in the manufacture of iron which took place in the latter part of the last century, while they vastly increased the demand for it, and thus gave a great stimulus to the working of this metal, and of coal also for its reduction, contributed much to the perfection of mining generally, by enabling the miner to employ iron pumps instead of wooden ones, which were before used. This change allowed a better construction and arrangement of the pit-work, one of the most important apparatus employed in mining, and hence greater depths have been attainable than might otherwise have been the case. Among many minor improvements which may be traced to the same

source may also be mentioned the laying down of iron tram-roads underground in mines, as well as their use upon the surface: the carriage of the mineral to different parts of the works has thus been greatly facilitated and economised.

Simultaneously with the improved machinery and apparatus introduced towards the close of the last century, great improvements also took place in the internal economy of mines and the arrangements of the underground works. The ancient mode of following down the ore by irregular isolated excavations, and of stoping the bottoms of the mines in the German manner, gave place to the present system of laying open the ground for discovery and extraction, by a well-arranged series of shafts, levels, and winzes. By this plan the ore or mineral is divided into more convenient masses for extraction, and can be worked much more economically than by the former mode of stoping or cutting away the ground in the bottom of the levels, as still practised on the Continent.

The most recent improvements which have been introduced into mining are those which regard the mechanical treatment of the ores after they have been extracted from the mine, and previous to their being fit for the furnace. The processes used for this purpose are technically termed "washing" and "dressing," by means of which the ore is freed from many of its earthy impurities, and thus rendered much richer for metal, in an equal bulk. In effecting this object several kinds of apparatus are employed, chiefly the stamping-mill, the crushing-mill, and the jigging-machine, the use of which has been known from time immemorial; but more attention has latterly been paid to their application, and it has also become far more general, to the great benefit of all mines, especially those in which a large proportion of the poorer ores are obtained. The competition with foreign mines, in which labour can be obtained more cheaply than in this country, has done much to promote this class of improvements, which, though less striking than some others, have, within the last few years, been productive of extremely beneficial effects, and may still be considered as in progress.

The history of coal-mining is in great measure distinct from that branch of the art which we have been tracing, and which chiefly relates to the extraction of the metals. The introduction of gunpowder, the invention of the steam-engine, and the improved manufacture of iron, have formed however epochs of common importance to both, having greatly contributed to the present extended scale upon which our coalmines are worked. The great objects to which improvement has within the present century been directed are the ventilation of the works and the invention of lamps which should not be liable to explosion on contact with the fire-damp. The system of ventilation in our collieries has been greatly improved of late years by Mr. Buddle and others; and the beautiful and well-known invention of the safety-lamp, in 1815, by Sir Humphry Davy, has afforded the miner a valuable though not in all cases an effectual preservative against explosion. [LAMP, SAFETY.] One of the most important events in the recent history of mining in this country is the establishment of suitable means of instruction for the mining engineer. This desideratum was first supplied by the university of Durham, which opened a class for instruction in civil and mining engineering, in January, 1838. In the latter part of the same year a similar department was opened in King's College, London; and a similar institution was organised by Sir Charles Lemon at Truro, in Cornwall, but, unfortunately, it did not meet with the support it so justly merited, and has since been discontinued. The local positions of the Durham University and of the Truro institution were highly favourable to the joint acquisition of theoretical and practical instruction-an advantage in which neither King's College nor the Government School of Mines in Jermyn Street can participate, although both must afford valuable preliminary instruction to the mining engineer. These various institutions can hardly fail, in time, to produce an important effect on the mining industry of this country.

Mineral Deposits.-In proceeding to treat of the practice of mining, some preliminary details will be useful; for as mining operations are of course in great measure regulated by the nature of the mineral or metalliferous deposits to which they are directed, and by which are determined the form and construction of the mine, and much of its internal economy, it will be necessary briefly to glance at this subject, and to point out some of the most important modes in which mineral masses are presented by nature to our research. Of the various classes into which mineral deposits may be divided, it will be sufficient for our present purpose to notice four only,-veins, beds, masses, and fragmentary deposits,-each of which is the repository of vast mineral treasures, but more especially the first two.

Veins have originally been, in most cases, long, narrow, and irregular fissures, traversing the rocky crust of the globe, which they penetrate to an unknown depth, and often at a high angle of inclination. They are for the most part filled with sparry and stony substances, called the "veinstone," or the "gangue" of the vein, but contain here and there irregular masses or "bunches" of the metallic ores, often of immense size and value, and which it is the principal business of the miner to discover and extract. Most of the metals are of common occurrence in veins, as, in this country, copper, tin, lead, and zinc, to which, in other parts of the world, may be added gold and silver.

Beds are layers of mineral substances interposed between the strata of solid rock, which, except in their containing valuable matter, they