They would be screwed to the upright at the hinge end. (These are wood framed Venetian blinds -- with wood slats opened or closed by a vertical piece of wood hooked to the edes of the slats with tiny staples in both parts). The knobs stick up and down beyond the blind's frame, and pass through flat rings screwed to the top and bottom of the wooden window frame to allow the blinds to pivot.
I've seen something like this in South Texas in the house in which I did some of my growing up. The green showing in a chip on the end of the knob in the close up is a close match to my memory of the very oxidized green paint on those on some windows on the house. It was about 1955 when I would last have regularly seen these (so I would have been about fourteen years old at the most), and I have no idea how old they were at that time -- but I would guess that they were at least thirty years old or more. (Rain was quite infrequent there, so a wooden structure like this would last a lot longer than here in Northern Va.
Hmm ... the pattern of holes looks like they are designed to accept flat-head screws from one side rather than to be a way to bond to the masonry.
Enjoy, DoN.