Denny, K8DO wrote:
"The currents continue to stream past the standing point (in both
directions) carrying both the carrier and its instantaneous modulation
products with it."

Yes. Point is the a-c amplitudes of both forward and reflected currents
are varing at the r-f frequency but their phase relationship is fixed so
that the two currents may be represented by vectors (phasors) at the
point.

Amplitude modulation is a mixing process which produces sum and
difference frequencies that are not synchronized with either original
frequency. Stable frequency generators produce fixed locations for
maxima and minima*along the transmission line, however.

Cecil`s tests were designed to demonstrate atanding waves and phasor
addition. They likely worked as intended.

Best regards, Richard Harrison, KB5WZI