J vs. I

I've been teaching my 10 year old niece how to read our ancestors' old Bohemian records, and we came across an excellent example of how the capitol letters I and J were written identically by many German scribes.  In these cases, the only way to differentiate between these two capitol letters is to keep reading: if the letter is followed by a vowel it is a J, or if it is followed by a consonant it is an I.  

Here we see the given names Joseph and Ignaz
written with the same initial letter.