Can Loan Words Help You Date Sound Changes?

If you're developing within a con world, several languages in parallel, you want to put dates on on stages of the language. Loan words are interesting for real historical linguistics in that they can help you date sound changes. So if you've got a word that has a particular vowel, say in a position that you would normally expect to change, but it didn't, then you can say something about what happened. Or rather when we don't think we've said enough about time. William: Do not ignore the neo-Gramarian hypothesis.