The Diamond                   35
	ncased for ages is pertinent and worthy of some space in even so compact a book as the present. The diamond-bearing blue earth from the mines is automatically dumped into ore bins and thence conveyed in trucks drawn by endless wire rope and impelled by steam to the deposit-ing floors on the receiving grounds, which are planed and rolled hard as if for use as tennis courts or brick drying floors. The De Beers mine floors are rectangular sections, six hun­dred yards long and two hundred yards wide, and extend for four miles; each floor holds about fifty thousand truck loads, a full load weighing about sixteen hundred pounds; spread out until about a foot in thickness, such a load covers about twenty-one square feet. In this great area of blue earth lie the invisible dia­monds, for, although some of the rough dia­monds may be as large as walnuts, persons walking over the blue earth have almost never seen one. Weathering disintegrates the breccia or blue earth, which process is carried and hast­ened by wheeled harrows drawn by steam trac­tion engines. Eain accelerates this weathering Process and drought retards it. The blue ground from Kimberley mine becomes well pul­verised in six months, with the favourable con-