Do you suppose the report was making a snide observation about logging: "one of eight steam engines which comprised the backbone of the logging industry of El Dorado County's western slop [sic]"?
I just found a similarly amusing error in a web page I was editing; I did not write the page, but I did recently totally revamp the site. I'm now reading the web pages about fascinating history of the area, and in an article about turquoise mining there, found that there once were auctions of turquoise from another part of the world, auctions held by someone who may have been a relative of George Bernard Shaw, "...the Shaw [sic] of Persia...".