What is "trials and errors"

Usage examples of "trials and errors".

To withdraw from the trials and errors of this campus, sit under an elm, and meditate upon the unutterable Answer -- that was the way to Commencement Gate, I saw now, the sole Way, and I meant to follow His example as soon as I flunked WESCAC.

If you travel for a sufficient length of time, one of the tunnels is bound to bring you back to a place you've been before, and if you keep precise record of the button you pushed on each panel of each tunnel that you traveled and if enough of you do this, each of you leaving a record-communication at each panel before you go through another tunnel, so that if one of your teammates should pass the same way - I explain it badly, but you can see how, after many trials and errors, in a few instances tunnel and panel relationships can be worked out.