They were 'safety chutes' for fire evacuations.... A lot of the 'multi-storied' schools in the area had them until the late 40's or early 50's.
Until they were deemed 'unsafe' by the powers-that-be or the powers behind the powers-that-be
I can remember, like xABD, keeping them 'polished' and cobweb free during the summers.... it was 'hard work' climbing up them from the bottom with your tennis shoes pressed against the sides to get you up till you decided you were high enough or just couldn't take any more...
You NEVER wanted to go in a group and attract the attention of the local constabulary agents, who frowned mightily on the 'maintenance' you were doing
Ah, for the simpler times!!
Bob K. rnkiii