Very interesting set of instruments.
Those of us who remember the good old days before sat navs and gps took us down long winding country roads and into rivers that arn't supposed to be there we used to have a thing called a map................here are some to refresh the memory of the good old days.
Of course these pieces of paper where of no use if you didn't know how to use them or read them. As such learning orienteering was vital.
Below are some publications to assist in the development of this skill.
Very cool stuff and thanks for showing
[h=3]e plu·ri·bus u·num[/h]
I have seen the Marschleistungen with small compasses in the circle at the top. NH