As late as the early 1960s the DuPont finance department was using full keyboard mechanical calculators. OK with add and subtract; bit long in time for multiplication and near endless grinding on division. When division was need, you calculated the reciprocal of the number and then used that for multiplication.

The machines in the background are most likely Burroughs glass-sided adding machines, whereas the small ones closer up are Burroughs direct adders.

The direct adder doesn't print and it only does simple adding, so it can be much smaller.

The ladies in the foreground have little adding machines on their desks. The folks in the background have giant mechanical calculators with printers. I assume they were working percentages or some other task that requires number-crunching effort.

I'd be interested in a closer photo of the calculators, if one is available. They are quite impressive. Mainly, in that none of them have side covers.

In today's office environment, open office plans are "new". Hah!

Manufactured until 1930, the GE Model 75423 electric fan. I have an unrestored near perfect one in my collection. I hope they are bolted down as they are extremely heavy.

Now that we've figured out the radiator situation, it is interesting to note that they are not in use this particular November 24th, and instead the GE fans are all running and the windows open to keep the clerks cool. I also see no coats hanging, so it's not just because of a hot office.

The pipes are for the steam radiators under the windows. You can barely see one next to the lady on the right.

Items of note:

Clerks are not 100% female.

Hat racks are crowded.

I was curious about the pipes too. But I soon realized they had to be to the radiators for the floor above. The configuration allows for expansion. The bare concrete structure doesn't allow for hiding the overhead utilities.

But what a collection of hats and umbrellas! No girl should be without.

There is a radiator under each window. The pipes feed the radiators on the floor above.

Steam heat pipes.

I thought it was a single pipe system, but a closer look seems to indicate that the "riser" pipes are not the same size, so it is more likely a two-pipe system.

Perhaps a little older than most of the girls, she's in the center of the photo. She has light colored hair, a kind gaze, and a slight smile. I involuntarily smiled back.

We can see a radiator under the window at the right, so the pipes are probably the feed and return pipes for the radiators on the next floor.

What a strange configuration of pipes along the ceiling above the windows. Certainly not heat or fire supression related.

That's "Desk Operating System".