This is more than a trip through a series of tunnels. It is a primordial study in how to compose a motion picture through a series of internal frameworks.
It took about a quarter of a century for film makers to finally settle on this method. From 1903 through about 1920 there was a strong movement that held that the way to rearrange the composition of a picture was through an iris -- and some odd ones were used, including keyhole-shaped irises. By about 1920, though, the vast majority of film makers had settled on composition through internal frames, although irising survived in the more traditional formats, like westerns and trailers, until the 1940s.
