He's operating a peep-show. (There's a picture of another one below.) Essentially it was a portable entertainment consisting of a box which could be carried on the back like a pack and a small folding table to stand it on. There was also a flap somewhere which could be opened to let in light. Customers looked through the round holes. Inside there might be a representation of a royal procession or a sea-battle painted on a long roll of paper. The showman would wind the roll across the field-of-view, giving a very primitive impression of movement or progression. The showman could them give a commentary. Other subjects could be the story of a notorous and recent "horrid murder" - the crime, the capture, trial, imprisonment and execution, etc. More sophisticated peep-shows used articulated images operated by rods, so sword-arms could slash, horses could gallop, and so on. The squirrel on the treamill, ringing the bells, is just an attention-getter! Tom