Thanks to Henrik and Séverine who alerted us that Chamonix is misspelled on the map!
In the index the spelling is Chamonix but on the map Chamounix. In the next edition, we get to decide which one to use! In early editions of the book, the spelling is Chamounix with a "u", see The Project Gutenberg here. We will probably use the spelling from the first edition but refer to today's spelling. Please read more about Frankenstein in the excellent The Pennsylvania Electronic Edition here. The spelling seems to have been a topic for a long time, the text in the image is from Chamonix and the Range of Mont Blanc, A Guide. By Edward Whymper, 1896 (University of Minnesota, Google Books).
Another misprint is that "the 1838 edition" should be "the 1831 edition". We apologize for this and will change it in the next edition of the map which will be printed soon!