In practice it may be considerably less, owing to leakage at the valves and between the piston and cylinder.
Thus, while nothing but leakage occurs the uniform horizontal line is continued.
If, however, there is leakage, the current received on the galvanometer will be less than the current sent out, and the result will be a deflection of the needle proportional to the amount of leakage.
In this case the electric charge exists at the point where the stem is attached, and there leakage by creeping takes place.
The introduction of inductance coils into such circuits renders them more susceptible to trouble from atmospheric electricity and more sensitive to leakage variations.