The last panel in this episode is ostensibly from the Cabin Boy’s Log. The cabin boy being, of course, the put-upon African American at whom so many racist slurs are lobbied over the course of the series. The wink at the reader is that the cabin boy is smarter than his racist employers suspect and his intelligence is easy to hide because they can’t imagine that anyone with a non-white skin color is anything but a savage.

The subtext is there if you’re willing to look for it, but on a quick read, this strip just comes across as supporting old school racist steampunk values, not subverting them. It’s not an easy strip to read. 

(Heavy Metal issue #39, June 1980 – Page 30 Professor Thintwhistle by Lupoff and Stiles)