A professional who tends gravity device that separates coal from refuse. Respnsibilities include:

• Tests solution in tank for specific gravity, adds pulverized magnetite, and starts oscillating rake to maintain constant density.
• Opens chute gate to admit coal mixture to tank.
• Observes coal as it floats over weir onto conveyor.
• Opens gate to draw off refuse that was raked into discharge chute.
• Recovers magnetite, drawn off with coal and refuse, from filtering device, using shovel and wheelbarrow.