Shutting Down Dynamo

—The load should first be gradually reduced, if po ible, by easing down the engine; then, when the machine is supplying little or no current, the main switch should be opened, This reduces the sparking at the switch contacts, and prevents the engine racing. When the voltmeter almost indicates zero, the brushes should be raised from contact with the commutator. The commutator brushes should not be raised while the machine is generating any considerable voltage; for not only is the insulation of the machine liable to be damaged by this proceeding, but in the case of large shunt dynamos an exceedingly violent shock is liable to be administered to the person lifting the brushes. When the dynamo is at rest, or only revolving slowly, and the brushes are raised from the commutator, the latter should be cleaned, if nece ary. When the machine is stopped it should be ore ue ONY cleaned up. The armature should be dusted with a pretty stiff brush to remove any adherent copper dust, dirt, etc., and the other portions of the machine should be thoroughly wiped with linen rags. Waste should not be used, as it is liable to leave threads, fluff, etc., on the projecting parts.