Some of my school classrooms in the 1970s had desks with holes which had previously contained ink wells; we still used fountain pens but the technology had moved on by then.
This makes me feel old (perhaps I am!) but I remember for most of my school life using those inkwells in the hole in the disk. The nibs we were issued with relied on the gap between the two halves to hold a supply of ink. If the gap was too wide a blot of ink was deposited on one's work on first contact, and conversely one too narrow produced half a letter in ink and then a scratch or even rip in the page. The ink was mixed from water and a seemingly almost-insoluble black powder in lumps.
At Secondary School you also had to be pretty quick at loading up with ink if the master was demanding that you wrote notes of what he said, and he was talking at conversational speed. The sound of nibs crashing into the ink pot could be hectic.
In the early-mid 1950s the Biro was an expensive luxury item. Fountains weren't that much less messy than nibs, trying to syphon ink into the container from a bottle (squeezing a 'bladder' inside the casing and releasing it) provided its own likelihood of ink escape.
I particularly remember at Primary School the School Inspector checked, amongst many other things, that we weren't wasting ratepayers' paper by leaving gaps of more than one line. Our teachers, worried about the consequences for themselves, also checked and censured for failure. At Secondary School every exercise book had the County and Borough Coats of Arms on the cover to reinforce their source.
The desks had a rail bent in a generally U-shape to connect the desk with the seat. The cross section and size of these rails had a strong similarity to that of bullhead narrow gauge rail line.