John Platts

CURIOSITIES RESPECTING MINES.

Diamond Mine in the Brazils—Mines of Peru—Volcanic Eruptions of Mud and Salt—Pitch Wells—Visit to a Coal-Pit.

Description of a Diamond Mine on the river Tigitonhonha, in the Brazilian territory; by Mr. Mawe.

“I could not (says the writer) resist the favourable opportunity now offered me of gratifying the curiosity which had so long occupied my mind, by visiting the diamond mines, in company with the principal officer in the administration of them, who was therefore qualified to furnish me with the amplest information. A fine horse was waiting for me at the door, and I rode up to the house of the governor, who introduced me to his amiable lady, daughters, and family, with whom I had the honour to take breakfast. Several officers of the diamond establishment arrived on horseback to accompany us, their presence being required on this occasion.

“Having arrived at the place, I remained here five days, during which I was occupied in viewing and examining various parts of the works, of which I shall here attempt to give a general description.

“The river Tigitonhonha is formed by a number of streams, and is as wide as the Thames at Windsor, and in general from three to nine feet deep. The part now in working is a curve or elbow, from which the current is diverted into a canal cut across the tongue of land round which it winds, the river being stopped, just below the head of the canal, by an embankment formed of several thousand bags of sand. This is a work of considerable magnitude, and requires the co-operation of all the negroes to complete it; for the river being wide and not very shallow, and also occasionally subject to overflow, they have to make the embankment so strong as to resist the pressure of the water, admitting it to rise four or five feet.

“The deeper parts of the channel of the river are laid dry by means of large caissons or chain-pumps, worked by a water-wheel. The mud is then carried off, and the cascalhao is dug up, and removed to a convenient place for washing. This labour was, until lately, performed by the negroes, who carried the cascalhao in gamellas on their heads; but Mr. Camara has formed two inclined planes, about one hundred yards in length, along which carts are drawn by a large water-wheel, divided into two parts, the ladles or buckets of which are so constructed, that the rotary motion may be altered by changing the current of water from one side to the other; this wheel, by means of a rope made of untanned hides, works two carts, one of which descends empty on one inclined plane, while the other, loaded with cascalhao, is drawn to the top of the other, where it falls into a cradle, empties itself, and descends in its turn. At a work called Canjeca, formerly of great importance, about a mile up the river on the opposite side, there are three cylindrical engines for drawing the cascalhao, like those used in the mining country of Derbyshire, and also railways over some uneven ground. This was the first and only machinery of consequence, which I saw in the diamond district, and there appear many obstacles to the general introduction of it. Timber, when wanted of large size, has to be fetched a distance of one hundred miles, at a very heavy expense; there are few persons competent to the construction of machines, and the workmen dislike to make them, fearing that this is only part of a general plan for suspending manual labour.

“The stratum of cascalhao consists of the same materials with that in the gold district. On many parts, by the edge of the river, are large conglomerate masses of rounded pebbles cemented by oxide of iron, which sometimes envelop gold and diamonds. They calculate on getting as much cascalhao in the dry season, as will occupy all their hands during the months which are more subject to rain. When carried from the bed of the river whence it is dug, it is laid in heaps, containing apparently from five to fifteen tons each.

“Water is conveyed from a distance, and is distributed to the various parts of the works by means of aqueducts, constructed with great ingenuity and skill. The method of washing for diamonds at this place, is as follows:—A shed is erected in the form of a parallelogram, twenty-five or thirty yards long, and about fifteen wide, consisting of upright posts, which support a roof thatched with long grass. Down the middle of the area of this shed, a current of water is conveyed through a canal, covered with strong planks, on which the cascalhao is laid two or three feet thick. On the other side of the area is a flooring of planks, from four to five yards long, imbedded in clay, extending the whole length of the shed, and having a slope, from the canal, of three or four inches to a yard. This flooring is divided into about twenty compartments or troughs, each about three feet wide, by means of planks placed on their edge. The upper ends of all these troughs (here called canoes) communicate with the canal, and are so formed that water is admitted into them between two planks that are about an inch separate. Through this opening the current falls about six inches into the trough, and may be directed to any part of it, or stopped, at pleasure, by means of a small quantity of clay. For instance, sometimes water is required only from one corner of the aperture, then the remaining part is stopped; sometimes it is wanted from the centre, then the extremes are stopped; and sometimes only a gentle rill is wanted, then the clay is applied accordingly. Along the lower ends of the troughs a small channel is dug, to carry off the water. On the heap of cascalhao, at equal distances, are placed three high chairs, for the officers or overseers. After they are seated, the negroes enter the troughs, each provided with a rake of a peculiar form, and short handle, with which he rakes into the trough about fifty or eighty pounds weight of cascalhao. The water being then let in upon it, the cascalhao is spread abroad, and continually raked up to the head of the trough, so as to be kept in constant motion. This operation being performed for the space of a quarter of an hour, the water then begins to run clearer; having washed the earthy particles away, the gravel-like matter is raked up to the end of the trough; after the current flows away quite clear, the largest stones are thrown out, and afterwards those of inferior size, then the whole is examined with great care for diamonds. When a negro finds one, he immediately stands upright and claps his hands, then extends them, holding the gem between his fore finger and thumb; an overseer receives it from him, and deposits it in a gamella or bowl, suspended from the centre of the structure, half full of water. In this vessel all the diamonds found in the course of the day, are placed, and at the close of work are taken out, and delivered to the principal officer, who, after they have been weighed, registers the particulars in a book kept for that purpose. When a negro is so fortunate as to find a diamond of the weight of 17½ carats, much ceremony immediately takes place; he is crowned with a wreath of flowers, and carried in procession to the administrator, who gives him his freedom, by paying his owner for it. He also receives a present of new clothes, and is permitted to work on his own account. When a stone of eight or ten carats is found, the negro receives two new shirts, a complete new suit, with a hat, and a handsome knife. For smaller stones of trivial amount, proportionate premiums are given. During my stay at Tejuco, a stone of 16½ carats was found: it was pleasing to see the anxious desire manifested by the officers that it might prove heavy enough to entitle the poor negro to his freedom; and when, on being delivered and weighed, it proved only a carat short of the requisite weight, all seemed to sympathize in his disappointment.

“Many precautions are taken to prevent the negroes from embezzling diamonds. Although they work in a bent position, and consequently never know whether the overseers are watching them or not, yet it is easy for them to omit gathering any which they see, and to place them in a corner of the trough for the purpose of secreting them at leisure hours; to prevent which they are frequently changed while the operation is going on. A word of command being given by the overseers, they instantly move into each others’ troughs, so that no opportunity of collusion can take place. If a negro be suspected of having swallowed a diamond, he is confined in a strong room until the fact can be ascertained. Formerly, the punishment inflicted upon a negro for smuggling diamonds, was confiscation of his person to the state: but it being thought too hard for the owner to suffer for the offence of his servant, the penalty has been commuted for personal imprisonment and chastisement. This is a much lighter punishment than that which their owners, or any white man, would suffer for a similar offence.

“There is no particular regulation respecting the dress of the negroes: they work in the clothes most suitable to the nature of their employment, generally in a waistcoat and a pair of drawers, and not naked, as some travellers have stated. Their hours of labour are from a little before sunrise until sunset, half an hour being allowed for breakfast, and two hours at noon. While washing, they change their posture as often as they please, which is very necessary, as the work requires them to place their feet on the edges of the trough, and to stoop considerably. This posture is particularly prejudicial to young growing negroes, as it renders them in-kneed. Four or five times during the day, they all rest, when snuff, of which they are very fond, is given to them.

“The negroes are formed into working parties, called troops, containing 200 each, under the direction of an administrator and inferior officers. Each troop has a clergyman and a surgeon to attend it. With respect to the subsistence of the negroes, although the present governor has in some degree improved it, by allowing a daily portion of fresh beef, which was not allowed by his predecessors, yet I am sorry to observe that it is still poor and scanty; and that in other respects they are more hardly dealt with than those of any other establishment which I visited: notwithstanding this, the owners are all anxious to get their negroes into the service, doubtless from sinister motives.

“The officers are liberally paid, and live in a style of considerable elegance, which a stranger would not be led to expect in so remote a place. Our tables were daily covered with a profusion of excellent viands, served up on fine Wedgewood ware, and the state of their household generally corresponded with this essential part of it. They were ever ready to assist me in my examination of the works, and freely gave me all the necessary information respecting them.

“Having detailed the process of washing for diamonds, I proceed to a general description of the situation in which they are found. The flat pieces of ground on each side the river are equally rich throughout their extent, and hence the officers are enabled to calculate the value of an unworked place, by comparison with the amount found on working with the part adjoining. These known places are left in reserve, and trial is made of more uncertain grounds. The following observation I often heard from the intendant: ‘That piece of ground (speaking of an unworked flat by the side of the river) will yield me ten thousand carats of diamonds, whenever we shall be required to get them in the regular course of working, or when, on any particular occasion, an order from government arrives, demanding an extraordinary and immediate supply.’

“The substances accompanying diamonds, and considered good indications of them, are bright bean-like iron ore, a slaty flint-like substance, approaching Lydian stone, of fine texture, black oxide of iron in great quantities, rounded bits of blue quartz, yellow crystals, and other materials entirely different from anything known to be produced in the adjacent mountains. Diamonds are by no means peculiar to the beds of rivers or deep ravines; they have been found in cavities and watercourses on the summits of the most lofty mountains. I had some conversation with the officers, respecting the matrix of the diamond, not a vestige of which could I trace. They informed me, that they often found diamonds cemented in pudding-stone, accompanied with grains of gold, but that they always broke them out, as they could not enter them in the treasury, or weigh them with matter adhering to them. I obtained a mass of pudding-stone, apparently of very recent formation, cemented by ferruginous matter enveloping many grains of gold; and likewise a few pounds weight of the cascalhao in its unwashed state. This river, and other streams in its vicinity, have been in washing many years, and have produced great quantities of diamonds, which have ever been reputed of the finest quality. They vary in size: some are so small that four or five are required to weigh one grain, consequently sixteen or twenty to the carat: there are seldom found more than two or three stones of from seventeen to twenty carats in the course of a year, and not once in two years is there found throughout the whole washings a stone of thirty carats. During the five days I was here, they were not very successful; the whole quantity found amounted only to forty, the largest of which was only four carats, and of a light green colour.

“From the great quantity of debris, or worked cascalhao, in every part near the river, it is reasonable to calculate that the works have been in operation above forty years; of course there must arrive a period at which they will be exhausted, but there are grounds in the neighbourhood, particularly in the Cerro de St. Antonio, and in the country now inhabited by the Indians, which will probably afford these gems in equal abundance.”

The Mines of Peru.—There are great numbers of very rich mines which the waters of the ocean have invaded. The disposition of the ground, which from the summit of the Cordilleras goes continually shelving to the South Sea, renders such events more common at Peru than in other places. This has been in some instances remedied. Joseph Salcedo, about 1660, discovered, near Puna, the mine of Laycacoto. It was so rich that they often cut the silver with a chisel. It was at last overflowed with water; but in 1740, Diego de Bacua associated with others to divert the springs. The labours which this difficult undertaking required, were not finished till 1754. The mine yields as much as it did at first. But mines still richer have been discovered; such as that of Potosi, which was found in the same country where the Incas worked that of Parco. An Indian, named Hualpa, in 1545, pursuing some deer, in order to climb certain steep rocks, had hold of a bush, the roots of which loosened from the earth, and brought to view an ingot of silver. The indian had recourse to it for his own use. The change in his fortunes was remarked by one of his countrymen, and he discovered to him the secret. The two friends could not keep their counsel and enjoy their good fortune. They quarrelled; on which the indiscreet confidant discovered the whole to his master Villaroel, a Spaniard. Upon this the mine was worked, and a great number of others were found in its vicinity, the principal of which are in the northern part of the mountain, and their direction is from north to south. The fame of Potosi soon spread abroad; and there was quickly built at the foot of the mountain a town, consisting of 60,000 Indians, and 10,000 Spaniards. The sterility of the soil did not prevent its being immediately peopled. Corn, fruit, flocks, American stuffs, and European luxuries, arrived from every quarter. In 1738 these mines produced annually near £978,000, without reckoning the silver which was not registered, and what had been carried off by fraud. From that time the produce has been so much diminished, that not above one-eighth part of the coin which was formerly struck, is now made. At all the mines of Peru, the Spaniards, in purifying their gold and silver, use mercury, with which they are supplied from Guanca Velica. The common opinion is, that this mine was discovered in 1564. The trade of mercury was then free; it became an exclusive trade in 1571. At this period all the mines of mercury were shut; and that of Guanca Velica alone was worked; the property of which the king reserved to himself. It is not found to diminish. The mine is dug in the very large mountain of Potosi, sixty leagues from Lima. In its profound abyss are seen streets, squares, and a chapel, where the mysteries of religion on all festivals are celebrated. Millions of flambeaus are continually kept to enlighten it. The mine of Guanca Velica generally affects those who work in it with convulsions; and the other mines, which are not less unhealthy, are all worked by the Peruvians. These unfortunate victims of an insatiable avarice are crowded all together, and plunged naked into these abysses, the greatest part of which are deep, and all excessively cold. Tyranny has invented this refinement in cruelty, to render it impossible for any thing to escape its restless vigilance. If there are any wretches who long survive such barbarity, it is the use of cocoa that preserves them.

We shall incorporate in this chapter, the following interesting account of Volcanic Eruptions of Mud and Salt, in the Island of Java; by T. S. Goad, Esq. of the Honourable Company’s Bengal Civil Service.

“Having received (says the writer) an extraordinary account of a natural phenomenon in the plains of Grobogan, fifty pals (or miles) north-east of Solo, a party, of which I was one, set off from Solo on the eighth of September, 1815, to examine it.

“On approaching the village of Kuhoo, we saw, between two trees in a plain, an appearance like the surf breaking over rocks, with a strong spray falling to leeward. The spot was completely surrounded by huts, for the manufacture of salt, and at a distance looked like a large village. Alighting, we went to the Bludugs, as the Javanese call them. They are situated in the village of Kuhoo, and by Europeans are called by that name. We found them to be on an elevated plain of mud, about two miles in circumference, in the centre of which immense bodies of salt mud were thrown up, to the height of from ten to fifteen feet, in the form of large globes, which, bursting, emitted volumes of dense white smoke. These large globes or bubbles, of which there were two, continued throwing up, and bursting seven or eight times in a minute At times they throw up two or three tons of mud. We got to leeward of the smoke, and found it to smell like the washing of a gun-barrel.

“As the globes burst, they threw the mud out from the centre with a pretty loud noise, occasioned by the falling of the mud upon that which surrounded it, and of which the plain is composed. It was difficult and dangerous to approach the large globes or bubbles, as the ground was all a quagmire, except where the surface of the mud had become hardened by the sun; upon this we approached cautiously to within fifty yards of the largest bubble, or mud pudding, as it might very properly be called, for it was of the consistency of a custard-pudding, and of very considerable diameter: here and there, where the foot accidentally rested on a spot not sufficiently hardened, it sunk, to the no small distress of the walker.

“We also got close to a small globe or bubble, (the plain being full of them of different sizes,) and observed it closely for some time. It appeared to heave and swell, and when the internal air had raised it to some height, it burst, and fell down in concentric circles, in which shape it remained quiet until a sufficient quantity of air was again formed internally, to raise and burst another bubble. This continued at intervals from about one-half to two minutes. From various other parts of the quagmire round the large globes or bubbles, there were occasionally small quantities of mud shot up like rockets to the height of twenty or thirty feet, and accompanied by smoke. This was in parts where the mud was of too stiff a consistency to rise in globes or bubbles. The mud at all the places we came near was cold on the surface, but we were told it was warm beneath. The water which drains from the mud is collected by the Javanese, and by being exposed in the hollows of split bamboos to the rays of the sun, deposits crystals of salt. The salt thus made is reserved exclusively for the Emperor of Solo. In dry weather it yields thirty dudjins, of one hundred catties each, every month; but in wet or cloudy weather, less.“In the afternoon we rode to a place in a forest, called Ramsam, to view a salt lake, a mud hillock, and various boiling, or rather bubbling, pools. The lake was about half a mile in circumference, of a dirty looking water, boiling up all over in gurgling bodies, but more particularly in the centre, which appeared like a strong spring; the water was quite cold, and tasted bitter, salt, and sour, and had an offensive smell. About thirty yards from the lake stood the mud hillock, which was about fifteen feet high from the level of the earth. The diameter of its base was about twenty-five yards, its top about eight feet, and in form an exact cone. The top is open, and the interior keeps constantly working, and heaving up mud in globular forms, like the Bludugs. The hillock is entirely formed of mud which has flowed out of the top; every rise of the mud was accompanied by a rumbling noise from the bottom of the hillock, which was distinctly heard for some seconds before the bubbles burst. The outside of the hillock was quite firm. We stood on the edge of the opening and sounded it, and found it to be eleven fathoms deep. The mud was more liquid than at the Bludugs, and no smoke was emitted from the lake, hillock, or pools.

“Close to the foot of the hillock was a small pool of the same water as the lake, which appeared exactly like a pot of water boiling violently; it was shallow, except in the centre, into which we thrust a stick twelve feet long, but found no bottom. The hole not being perpendicular, we could not sound it with a line.

“About 200 yards from the lake, were several large pools or springs, two of which were eight or ten feet in diameter. They were like the small pool, but boiled more violently, and smelt excessively. The ground around them was hot to the feet, and the air which issued from them quite hot, so that it was most probably inflammable; but we did not ascertain this. We heard the boiling at the distance of thirty yards from the pools, resembling in noise a waterfall. The pools did not overflow; of course the bubbling was occasioned by the rising of air alone. The water of one of the pools appeared to contain a mixture of earth and lime, and, from the taste, to be combined with alkali. The water of the Bludugs and the lake is used medicinally by the Javanese, and cattle drinking of the water are poisoned.”

Now follows an account of Pitch-Wells; from Dr. Holland’s Travels in the Ionian Isles, &c.—“The pitch-wells of Zante are a natural phenomenon, which may be regarded as among the antiquities of the isle; since they were known and described as early as the time of Herodotus, and are mentioned since by Pausanias, Pliny, and other authors. They are situated about ten miles from the city, and near the shore of the bay, on the southern side of the island. We visited this spot, which is called Chieri, a day or two after our arrival in Zante. A small tract of marshy ground, stretching down to the sea, and surrounded on other sides by low eminences of limestone, or a bituminous shale, is the immediate situation of the springs; they are found in three or four different places of the morass, appearing as small pools, the sides and bottom of which are thickly lined with petroleum, in a viscid state, and, by agitation, easily raised in large flakes to the surface. The most remarkable of these pools is one of a circular form, about fifty feet in circumference, and a few feet in depth, in which the petroleum has accumulated to a considerable quantity. The water of the spring, which is doubtless the means of conveying the mineral upwards to the surface, forms a small stream from the pool, sensibly impregnated with bituminous matter, which it deposits in parts as it flows through the morass: the other pools are of similar character. The petroleum is collected generally once in the year; and the average quantity obtained from the springs is said to be about 100 barrels; it is chiefly used for the caulking of vessels, not being found to answer equally well for cordage.”

We close this chapter with Mrs. Wakefield’s account of her Visit to a Coal-Pit.—“Near the town of Newcastle, in the county of Northumberland, are vast beds of coal, which lie far beneath the surface of the earth: they are often found at the depth of 100 feet. Our visit to one of them was rather a droll adventure. The first ceremony was, to put on a kind of frock that covered us all over, to prevent spoiling our clothes. We were then shewn a prodigious steam-engine at work, at the mouth of the pit, in order to drain off the water; and close to it, a ventilator for purifying the air in the pit. Our guides now seated us on a piece of board, slung in a rope like the seat of a swing, and hooked to an iron chain, which was let gently down the suffocating hole by the assistance of six horses. I must confess, I did not like this mode of travelling: my spirits were, however, rather cheered when I reached the solid bottom, and saw my friend at my side. He congratulated me on my safe arrival; and pointed to a huge fire, burning for the purpose of keeping the air in proper temperature. Gaining courage by a nearer examination, I walked about the chambers with as much ease as if they had been the apartments of a dwelling-house. The coal is hollowed out in spaces of four yards wide, between which are left pillars of coal to support the roof, ten yards broad, and twenty deep. After exploring a dozen or two of these little apartments, our curiosity was satisfied, as there was nothing more to be seen but a repetition of the same objects to a vast extent. A number of horses live here for years together, and seem to enjoy themselves very comfortably: they are employed to draw the coal from the subterraneous passages to the bottom of the opening of the pit. The machine which raises the coal to the surface of the earth, is worked by stout horses. The coal is brought in strong baskets, made of osier; they contain each 12 cwt. and while one ascends, the other descends. A man receives these baskets as they arrive at the top, and places them on a dray, having hooked an empty basket on, instead of the full one. Before he drives the dray to a shed at a little distance, where he empties his load, the dust passes through holes prepared to receive it; while the large coals roll down the declivity in heaps, where they are loaded in waggons, and carried to wharfs on the river side, to be put on board the vessels that wait to convey them to distant parts. The waggons, very heavily laden, run without horses to the water side, along a road ingeniously formed in a sloping direction, with grooves to fit the waggon wheels, and make them go more readily. The dust, which is too small for common fires, is put into a kiln well heated, and when it is burnt, the particles unite, and run into large cakes or masses: in that state it is called coke, and this substance is used in many manufactories, where a strong heat is required.

“There are also coal-mines in several other parts of England. Near Whitehaven, in the county of Cumberland, are some that extend half a mile under the sea. The collieries employ a great number of hardy sailors, who, in their frequent coasting-voyages, are accustomed to face all the dangers of a sea-life. In time of war they contribute to man our navy; and, from their courage and skill, form a very valuable part of the crews.”