 Used a gimmick called "Emergo" in theaters. When the skeleton rises  from the acid vat in the film, a lighted plastic skeleton on a wire  appeared from a black box next to the screen to swoop over the heads  of the audience. The skeleton would then be pulled back into the box  as Vincent Price (I) (qv) reels in the skeleton in the film. Many  theaters soon stopped using this "effect" because when the local  boys heard about it, they would bring slingshots to the theater;  when the skeleton started its journey, they would pull out their  slingshots and fire at it with stones, BBs, ball bearings and  whatever else they could find.