From The Collaborative International Dictionary of English v.0.48 [gcide]:
Pan \Pan\, v. t. [imp. & p. p. Panned; p. pr. & vb. n.
Panning.]
1. (Mining) To separate, as gold, from dirt or sand, by
washing in a kind of pan. [U. S.]
[1913 Webster]
We . . . witnessed the process of cleaning up and
panning out, which is the last process of separating
the pure gold from the fine dirt and black sand.
--Gen. W. T.
Sherman.
[1913 Webster]
2. To criticise (a drama or literary work) harshly.
[PJC]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
panning \pan"ning\, n.
The act or process in which heavier ores are concentrated by
agitating a sample of crushed ore under water in a shallow
pan, thus washing away the lighter particles from the sample;
as, panning for gold. See pan[1], v. t. and pan[1], v. i.
[PJC]