Ruhmkorff’s Coil

—A form of induction coil perfected by Ruhmkorff: it consists of two insulated coils: one, the primary, having few turns of comparatively coarse wire, and the other, the secondary, with many turns of fine wire, wound upon a hollow cylinder enclosing a core of soft iron wires; the primary is joined to a battery, and includes an interrupter and commutator. The number of magnetic lines created and destroyed at each make and break is the same, bus by the use of a condenser, the current at make is caused to take a considerable fraction of time to row, while at break the ce ation is instantaneous. he rate of cutting of the magnetic lines is therefore much greater at break than at make. The effect of the condenser is to suppre the counter current at make and to increase the direct electromotive force at break. The sparks are longer, and pa only one way. The condenser does this by the action known as electric resonance,