Page:Popular Science Monthly Volume 21.djvu/633

Rh diamonds, except that with which they make them disappear if the vigilance of the superintendent is relaxed for an instant. I can not describe all the artifices employed, but I should remark that, since the works have become free, fraud has greatly diminished. Under the old rule it overtook half the diamonds in the gravels.

Difficulties of another kind are presented when the precious gravels are situated in the beds of the rivers. Since the channels have been deeply cut in the rock, and are bordered by steep cliffs, it is impossible to construct lateral sluices for turning the water away from them, except at an expense which even the magnificent return that is anticipated will not justify. A quicker and more simple process has been devised. The river is dammed, and a flume is made of planks to carry the water from the dam to some three or four hundred yards below. The intervening space between the dam and the end of the flume, in which the precious gravels of the caldeiroes are supposed to be situated, is thus left free from running water, while the water which stands upon it and that which reaches it by infiltration are removed by pumps worked by water-wheels. The work must be done quickly when this system is employed, for there is no time to lose. The river is generally docile enough during the dry season, from May to October; but, if only a slight storm comes on, it is transformed at once into a torrent that nothing can resist, and which carries off dams, wheels, and viaduct. This is what happens, as a rule, fifty times out of a hundred. I know of diamond-seekers who have recommenced for three or four years in succession the same works, to have them every time destroyed under their eyes by sudden freshets. Then a fortunate season has amply recompensed them for all that they had lost. Others have just had time to work for a few days in the rich beds, a few cubic yards of which have yielded them hundreds of carats of diamonds; but how many have exhausted all their resources without reaching this promised land! Nevertheless, no machines, or barrows, or inclined planes are employed, notwithstanding the enormous force furnished by the fall of water in the race is at the disposal of the operator; only picks, shovels, levers to raise the rocks, and, for means of transportation, laborers, who carry on their heads large wooden troughs, which others fill with sand and stones. Nothing can be more picturesque than these great trenches, where crowds of negroes are moving about like ants in an ant-hill, running in gangs to receive their loads, and carrying them away in groups, while they intone songs, which are almost always in the language of the African coast. The excavation becomes deeper and more sinuous; groups of men, like clusters of bees, hang, by the aid of the most primitive of ladders, to the rock walls, and the work goes on with a feverish ardor. From time to time, the overseers probe the sand with long iron rods. Great is the rejoicing when the existence of the diamond-bearing cascalho beneath the sterile sands is revealed by a peculiar sound which all the miners know.