cliff-hanging illusions as used in early films

Above Advertisement for a Hal Roach 1923 film comedy starring Harold Lloyd, called Safety Last. It shows him hanging precariously from a high-rise window ledge, with a distant busy street below. But in fact that’s not the case. As shown in the diagram below (from E.G. Lutz, The Motion Picture Cameraman), it is all an ingenious camera trick, albeit one that looks utterly real. 

Lloyd posed for various scenes like this, such a below, in which he seems to be suspended from the clockface on a building. When movement is added, both that of the actor and those on the street, it is even more convincing.

Comparable tricks were later used by American artist and optical physiologist Adelbert (Del) Ames II in developing the Ames Demonstrations in Perception, which we have discussed at length in a triad of online videos, titled The Man Who Made Distorted Rooms.