From a rational standpoint, therefore, there evolved four different conceptual approaches to the design of a skyscraper:

1. the skyscraper consisted of a number of identical floors stacked one on top of the next, therefore, the facade should consist of a repetition of horizontals, alternating between the spandrel beams of each floor, and the glass infill between these. This concept would only be possible using the iron frame, as a lintel had to hung from the exterior face of the columns to support the spandrel beam at each floor. (Le Corbusier will call this concept, the “Free facade.”)

2. the skyscraper was simply a large, rectangular volume of space, therefore, the facade should be detailed so that it would be read as one continuous surface or enclosure of the interior volume (as if was wrapped in cellophane).

3. the skyscraper consisted of an iron skeleton frame, therefore, the facade should express the rectilinear grid that results from the columns and the beams.

4. the skyscraper’s proportions were overwhelmingly vertical, so why not reinforce the skyscraper’s overall massing by accentuating its verticality through emphasizing the continuity of its columns). No one has better expressed this design approach to the skyscraper than did Louis H. Sullivan in 1896:
“What is the chief characteristic of the tall office building? And at once we answer, it is lofty… It must be tall, every inch of it tall… It must be every inch a proud and soaring thing, rising in sheer exultation that from bottom to top it is a unit without a single dissenting line.”
However, contrary to Sullivan’s dictum, there were at least four ways that American architects evolved in the 1890s to rationally design a skyscraper. As in most things in life, there would not be, there is not only one, right way to design a skyscraper. Claude Perrault dispelled such an idea in 1683 when he introduced the validity of the subjective/arbitrary in aesthetics in his Ordonnance pour les cinq sortes de colonnes d’après la méthode des anciens (Ordinance for the five kinds of columns according to the method of the ancients).
(If you have any questions or suggestions, please feel free to eMail me at: thearchitectureprofessor@gmail.com)