Nope.

Thanks Les. I was going to guess there was some kind of Superman television series promotion going on, but these photos would predate any Superman TV show, wouldn't it? So costume day at the school makes sense. 

Here's one more image of "Johny Superman."



And here's some info from the Historic Old Central High School website about the cannon.



During the Spanish-American war, the ship Oquendo set sail from Cuba on July 3, 1898. Hours after its departure the Oquendo found itself aflame on a nearby beach with an American fleet claiming victory over its demise.

The Duluth City Council asked for a memento from this event and was granted the acquisition of the ship's cannon. There was only one catch -- the city must pay for all transportation costs for the cannon. The city paid the price, and the 17-foot, 6-ton cannon was to have led a serene life near the front of Old Central. Life for the cannon was however, at times, exciting.

There was a class of chemistry students who wanted to try their craft -- and some homemade explosives -- on the cannon. Needless to say, the windows that were blown out of the school were replaced, but the bill for them has long since been lost.

The cannon was sold as scrap iron in 1942 and was melted down and used during World War II. A flag pole was erected in 1949 on the spot where the cannon stood.