The Dutch digraph ij originated from the same custom. Originally written ii, later ij, and pronounced as a long i (English "ee"), the sound later shifted to be similar to English "eye", see the Dutch names for the cities Berlijn and Parijs. Meanwhile, the long i sound is now written as ie. IJ is the only Dutch digraph that tends to be treated as a single letter and is capitalized as such. In education in the Netherlands it is taught as the 25th letter instead of y, which does not occur in native Dutch words, and in the phone book it used to be sorted together (mixed) with y. But since the advent of computers it is generally sorted as i followed by j. There are a few place names like Ysselsteyn where Y is pronounced as IJ.
As far as preventing forgery/tampering with the number, it's funny because this applies to merely the smallest part.<p>The "j" instead of "i" prevents you from adding another 1 or 2 to the number, at most.<p>Meanwhile, you could still change "ii" to "vii" or "xii" or "lxii" or whatever on the left side.<p>And still often append "i" on the right side when it <i>doesn't</i> end in "j" -- "x" can still become "xj", "xij", "xvij", etc.<p>It's just funny that you'd bother at all with "j" when it achieves so little. I see that it was also a practice to draw a line over the number -- why not just draw a whole box around it?
Similar flourish to the "long s" once used in English to spell the "ss" gemination: <i>poſseſs</i> or <i>poſſeſs</i>.<p><a href="https://en.wikipedia.org/wiki/Long_s" rel="nofollow">https://en.wikipedia.org/wiki/Long_s</a>
I don't understand why it's clear that <i>xx</i> is terminated, but not clear that <i>iii</i> is terminated, requiring the last <i>i</i> to be a <i>j</i>.<p>(Furthermore, if you have additional syntax on it like a superscript <i>th</i>, why is the <i>j</i> still needed then. That's a pure onion in the varnish at that point; someone just using the <i>j</i> without thinking about its purpose and necessity.)
The most interesting thing is that that post sat for months without the answer "why" it was done, but chatgpt knew, from the comment added 2h ago.<p>The j was to prevent forgery, or altering the document. ii could be altered later to iii.. but if it was ij its obvious its been tampered with if it later appears as iji
Really interesting thanks for sharing. It's great to learn these little things which would have been well known at one point but start to be forgotten as time and society progresses.
"dot the i's and cross the t's" (related to the 1919 referenced answer <a href="https://genealogy.stackexchange.com/a/3751" rel="nofollow">https://genealogy.stackexchange.com/a/3751</a> ).
> if all the letters i and J are not dotted, the pharmacist may be in doubt as to the number intended.<p>Oh, is that where "dot the i's and cross the t's" comes from? I can imagine that saying being hammered into many medical practitioners back then.
They say that you should never fix a curfty system by rewriting it. The transition from Roman numerals to Arabic numbers is a great example of a situation in which you should ignore this advice.
> A j was used for the final i, to make it clear the number had ended.<p>Yeah I imagined this was the case. Same as other common ways to avoid misunderstanding (and possible forgeries)
Here I was hoping it was indicating a complex number, since i was already taken.<p>...on that note, how would one write complex numbers in Roman numerals, now that both i and j are taken?