Hidden Tension: Furness's Hockley House

Michael Lewis has shown us that the genius of Frank Furness was most provocatively unleashed in 1875 at the Thomas Hockley House (235 S 21st St). Lewis gives a brilliant reading of the significance of the house's corner porch in Architecture of the Violent Mind. I made a pilgrimage to the house and looked a bit more closely. It is an amazing composition, indeed. Looking closely at the juncture between the provocative tympanum and the columns, I noticed something that I haven't seen in the scholarly literature. The dramatic tympanum is raised above the springing of the supporting arch by a few inches. This gives it a sense of levitation that counterbalances the piece's heaviness. But if it does not rest on the springing, how is this massive block supported?

If one looks closely to the underside of the tympanum, one notices three grooves that seem like a tri-partite stone moulding. The middle groove, however, is just slightly darker. At closer inspection, it is clear that it is not stone at all, but rather an iron beam in tension inserted in the intrados of the arch. That's how the tympanum is supported. I returned with my camera to take a close up of that detail.

I include here a photo of the Hockley House porch for those that have never seen it.

In previous posts, I have been tracing the steel beam vernacular in Philadelphia (and in Greece) see here. The tension rod here adds another wonderful piece to the discussion. Soon after using exposed steel beams in his Broad Street Station, Furness used it in a house around the corner, which I will discuss later.