Huxley is such an accomplished scientist that he has made innovations in a variety of fields. Here is his contribution of a method to produce an accurate simulation with the minimum effort.
The calculation of an action potential requires determining the value of the membrane voltage at discrete time steps. Here are the steps of the process:
Huxley's error-correction method (page 523 of their fourth 1952 paper, reproduced here) allowed him to take longer steps and thus speed the process. In his method, instead of proceeding relentlessly from step to step, he paused at each step to estimate the computational accuracy of that step. He then adjusted the size of the next step to meet the accuracy required.
Surprisingly, these additional error calculations allow the integration to proceed much more rapidly than by simply keeping the step size constant but tiny.