By my knowledge of Sutterlin schrift that is not minus for 2 reasons, 1 it is September and 2 there is a punkt over the first i in both sentance!
It says minis which could be an abreviation for something or somewhere, in my own opinion.
I hope it helps you.
Andreas
p.s. and also the second sentance has no 12 in it , so I think the 12 of the first is writting of the postal system written after, it is both darker and slightly of line with the other script!