and unfettered movements of the pen are recorded on the paper without the pen touching it.
The problem, therefore, is to keep the ink electrified notwithstanding that some of the charge is continuously dissipated in the action of squirting the ink on to the paper. It is necessary to replenish the charge, and the apparatus for this purpose, which is also
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Fig. 4.
the invention of Lord Kelvin, is called the "replenisher." The apparatus gives the original charge and replenishes it from time to time. All the telegraph operator has to do is to twist a knob quickly. Fig. 4 is a diagrammatic representation of the essential parts of Lord Kelvin's replenisher. A and B are two segments of a metallic cylinder, insulated from each other and connected respectively
