It's a speed control gauge from a Swedish steam locomotive. Why? What did you think the Swedish word fart means?
Dalton Richards of the blog Railyard visited the Järnvägsmuseet, a train museum in Gälve, Sweden. This photo from there spoke powerfully to my inner twelve-year-old.
Looking up the word origin for "speed" - it seems that came from Old English "sped" and "spowan" which means prosper or succeed.
Google now has the info in the search result directly when I googled for "etymology speed"