A method for eliminating bismuth from molten lead with calcium and magnesium, in which the addition of calcium and magnesium is made in the form of lumps two Mg\u2014Ca alloys, one containing predominantly Mg, the other containing predominantly Ca, each having a liquidus temperature lower than 650\xb0 C. The locking device comprises a locking plate having a component engaging portion to engage one component, A surface of the locking plate is grooved to engage with a grooved surface carried by the other component. The geometry of the first and second electrodes creates a substantially uniform electric field when a voltage is applied to the first and second electrodes. The third-lens-group moves in such a manner that a distance from the fourth-lens-group at telephoto-end is narrower than a distance from the fourth-lens-group at wide-angle-end. The first computing device transmits the serviced first request to the client computing device. The outputs of the first and second transmission lines are coupled to the inputs of a differential receiver that may or may not be frequency compensated.