Page:Popular Science Monthly Volume 69.djvu/282

278 The other method is in diving to the bottom of rivers and taking out the cascalho from there. This method is confined to a small section of the district where the river runs through a natural canal

cut into the rock. The diving can only be done when the river is low and is chiefly done naked, though there are a few diving suits in use. The naked divers descend a pole planted in the river and fill a sack with the cascalho, which is taken on shore for washing. The ability of some of these men to go to great depths and stay under for long intervals is extraordinary. In some places attempt is made to work the old river bed, but this is done with great difficulty, as water will seep in almost as fast it can be bailed out, leaving little time for the collection of cascalho.

Whatever the method of taking the cascalho out, the great desideratum is an abundant supply of water for washing. Where it is possible water from mountain streams is conducted down by ditches and flumes, and into these the cascalho is thrown. It is worked with a hoe. by which method the lighter particles are washed away, thus leaving a greater concentration which includes the diamonds and carbons. The concentration is taken out of the ditches and accumulated until the week's end, when it is laboriously further concentrated in bateias.

This final concentration and wash-up requires considerable dexterity as well as strength. It consists in revolving and shaking the bowl that the portions of heavier specific gravity accumulate in the