I've always enjoying writing and have thought about submitting pieces for publication. In researching that, I came across the expression "over the transom" that the article mentions.
In publishing, "over the transom" refers to unsolicited manuscripts that authors submit. Traditionally, you see, an editor's office would have a transom window above the door, often left open for air flow.
So when s/he left for the day and locked the office, you would sneak in, climb up on a chair or ladder, and toss your manuscript through the window!
I can't imagine that much ever for published that way. Surely the cleaning crew just swept them up!