Page:Popular Science Monthly Volume 30.djvu/492

472. The "pulsator" is also often so employed as to dispense with the "panning" process.

At the "river-diggings" (on the Vaal) the diamondiferous deposit is imbedded between bowlders and mixed with fine red sand, and sometimes with lime. The diamonds are separated by sifting the earth through a machine called a "baby"—a kind of swinging sieve, which, the coarser pebbles having been taken out by another sieve impending above it, allows the medium-sized pebbles, supposed to contain diamonds, to roll into a tub, while the finer refuse sand passes through its meshes. The contents of the tub are then gravitated, and the heavier stones are turned upon a "sorting-table," and the diamonds picked out by careful scraping. An experienced digger can tell at a glance, from the appearance of the deposit, what chance there is of "finding well" in it. He knows by sight the heavier stones that occur in diamond-bearing ground, and their presence is a sure sign of diamonds being there too. This is particularly the case with a curiously marked pebble that is streaked with a succession of parallel rings, from which it has received the descriptive name of "banddoom" (bandround). The specific gravity of the "banddoom" is almost identical with that of the diamond, and, where the former is found, experience has taught that the latter may be confidently expected. Beautiful agates are also found in this deposit, as well as quartz-crystals, jaspers, chalcedony, but few garnets, and no iron pyrites or carbon, which occur so plentifully in the Kimberley mines. An assortment of "river-stones" forms a very pretty collection, and it is conceivable enough that, prior to the opening of the diggings, diamonds should have been picked up by the natives and valued as more than ordinarily pretty pebbles. The river-digging is, however, not very profitable in the face of the large returns given by the Kimberley mines, and is now relatively of but little importance.

The whole number of claims in the four mines of Kimberley and Beaconsfield is 3,238, covering about seventy acres of diamondiferous gravel. The whole property is assessed at £5,172,975, or at the rate of £75,000 per acre, and is divided among ninety-eight holders, forty-two of whom are joint-stock companies, and the remaining fifty-six private firms and individuals. The gross capital of the joint-stock companies, which hold 2,211 claims, is returned at £7,970,490; and that of the private holders is estimated at £1,624,900, making the gross capital of the entire mines £9,595,390. The annual expenditure in labor, material, etc., is not less than two million sterling, or ten million dollars. It has been estimated, by the comparison of information from various official sources, that the gross value of diamonds exported from the Cape Colony up to the end of 1885, exclusive of such as were not reported or were illicitly taken away, amounted to £35,000,000. The total yield of diamonds from the Vaal River to date has probably exceeded £2,000,000.