The Book of Curiosities

by John Platts

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

Through dark retreats pursue the winding ore, Search Nature’s depths, and view her boundless store; The secret cause in tuneful numbers sing, How metals first were fram’d, and whence they spring Whether the active sun, with chemic flames, Through porous earth transmits its genial beams; With heat impregnating the womb of night, The offspring shines with its paternal light: Or whether, urged by subterraneous flames, The earth ferments, and flows in liquid streams Purg’d from their dross, the nobler parts refine, Receive new forms, and with fresh beauties shine: Or whether by creation first they sprung, When yet unpois’d the world’s great fabric hung: Metals the basis of the earth were made, The bars on which its fix’d foundations laid; All second causes they disdain to own, And from th’ Almighty’s fiat sprung alone. Yalden.

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.