Believe me, I didn't understand it either.
There are actually cotton ropes on pulley's with weights inside the casings of the windows that allow them to be raised and lowered. It's similar to oldfashioned clotheline cord, in fact that is what we have bought to replace them.
The original windows are still in the house from when it was built in the '40s - nothing wrong with the windows, and they are not drafty, but much of the cording is starting to fray and snap.
In order to properly fix them we need to take down all the molding and take the windows out - that's when I'm going to finish painting them because then I won't have the problem of them sticking as the paint dries!!!.
Unfortunately time and weather have not permitted us to even start that part of the project.
I know, I know - WAAAAAAAAAY TMI!!!!!!!
Okay, now I understand, and no, it *wasn't* way TMI! Thanks for explaining that!