sizes to jigs. Large diamonds which have been separated from their envelope of blue are retained in the jig. The ground still holding the smaller diamonds passes out of the end of the jig and then through a series of rolls, screens, and jigs until the diamantiferous gravel is drawn from the bottom jigs into locked trucks running on tramways to the pulsator for further concentration and sorting.
The pulsator is an ingeniously designed but somewhat complicated machine for dealing with the diamantiferous gravel already reduced one hundred times from the blue ground, the pulsator still further concentrating it till the gravel is rich enough to enable the stones to be picked out by hand. The value of the diamonds in a load of original blue ground being about 30s., the gravel sent to the pulsator from the pans, reduced a hundredfold, is worth £150 a load. Stuff of this value must not be exposed to risk of peculation. 52
