Proof!

I’ve more or less run out of Lewis Hine photos of the Empire State Building construction, so let’s head south for Irving Underhill photographing the Woolworth construction about twenty years earlier:

The photo, from February 20, 1912, is titled “Woolworth Bldg. iron work” and shows the steel frame erected up to about the 16th floor. It appears there are three derricks up top for picking steel, as well as a whole bunch of masons’ scaffolds lower down; the masons are working on the facade at the fifth floor.

Some context: the very ornate building on the right is the old General Post Office at the foot of City Hall Park. The much-plainer building on the left is the Astor House hotel, built in 1836. The southern portion of the hotel would be demolished not long after this photo, and replaced by the Astor [office] Building; the northern portion would be replaced in the 1920s by the high-rise Transportation Building. The angle of the photo suggests that Underhill was looking out a window of the St. Paul Building at the intersection of Park Row and Broadway (the street we see in the foreground).

The steel frame of Woolworth is a masterpiece of early-1900s structural design. I’m pretty sure that most people understand, on some level, that the masonry exterior walls of a nearly-800-foot-tall building are not structural, even if they are visibly thick and look very heavy. But this photo allows me to point to a detail provided by the structural engineer, Gunvald Aus:

Those are support brackets – a form of hung lintel, if you prefer – to carry, at each floor, the terra-cotta veneer and brick back-up of the big masonry piers. And the form of the brackets – some beams projecting out from the spandrel beams and held in place by diagonal straps – is what you’d use if the only load you’re expecting is the weight of the supported masonry pushing down.

In case anyone had any doubts, this was designed to be a skeleton-frame building with a non-structural curtain wall.