Harry Blackstone Sr., while performing at one Saturday matinee, was interrupted by a fire marshal asking him and his crew to evacuate the packed theatre because the drugstore next door had caught fire. An explosion was possible, and there was a risk that poisonous gases could fill the theatre. Realizing that a panicked stampede could result in injuries to the many children in his audience, Blackstone thought quickly and came up with the idea to go on stage and phrase the evacuation instructions in the form of a trick. He announced that he wanted to perform the greatest effect they had ever seen, but because it was so big, they would all have to file outside of the theatre to see it. Blackstone and his crew lined up the audience in an orderly fashion, and ushered them out the back to safety.