Ottenhöfen im Schwarzwald is a town in the district of Ortenau in Baden-Württemberg in Germany.
This is possibly the town referred to in Twain's journal:
Pretty girl here. An infernal cuckoo clock in hotel where we took dinner Offenbosen 1 1/2 hour before Allerheiligen.
Twain did not like the way of expressing distances by the time taken to get there:
This cursed way of stating all distances by minutes & hours -- it means nothing. You don't know whether it is 15 M by telegraph, or lounging, or with a sheriff after you.