Covington Journal November 2, 1861
A steam gun, constructed on a new principle, is in course of manufacture at the gun shops of the Illinois Central Railroad. Several of the more prominent men of Chicago are interested in it, and it is believed by them to be the most terrific instrument of war yet invented. It is to be ready for trial in about a week.
Here are a couple of articles about something that may have been similar to what this story described.