Someone told me:
"The term “positive” can only mean in reference to some other voltage. ,,,, Hulda Clark and Bob Beck were saying that the signal must not cross zero and reverse direction."
which I did not understand. Your statement seems to clear things up. I looked at the scope and it appeared that Beck was using AC current and I have heard from others that he was using AC current (which may have been a wrong assumption). So therefore a resistor would be needed to be installed at the output of the full wave rectifier to ensure a positive offset, as Hulda Clark specified. This way the Beck zapper would be at 4 hertz positive offset.