Here the Travel and Tranportation Building reflects its purpose by incorporating the sky as part of its architecture. By including spires and cables, the open air effective becomes "tamed" in this frame of the postcard.
This postcard features triangular peaks of water formed by propulsion and motion. Again, scale of human to non-human is significant-- the people gazing at the fountain are dwarfed by the water's size and magnitude. Its triangular apex connotes direction, momentum, and nature as a resource. The fountain provides a gathering place and signifies leisure, rather than water used for cleaning, irrigation, or agriculture. The fountain and its shape serve the ideology of a future where power and water are luxuries, not bound to fulfilling tasks, but creating art.
The sun's rays are crucial to framing the Tower of Water. The yellow light denotes a rising or setting sun, in conversation with the surrounding dark sky. The tower shoots into the sky as a symbol of power and productivity, unaffected by diurnal cycles. By illustrating the "miracle" of mechanics, the Tower of Water continues to move, filter and tame water unaided by manpower.
Again, the use of triangular shapes creates forward and aggressive movement. Here, the strong stance in favor of progress contributes to its myth and cultural reception. The future is shown as a place of stability and managed resources, which could be a direct response to the droughts and decimated crops of the Midwest's Dust Bowl.