Notation of triplets in Bach’s *Orgelbüchlein*

Question

In the following piece from J.S. Bach’s Orgelbüchlein, the nearly constant triplet line seems to be incorrect:

The time signature is 3/2, but there are 9 eighth-note triplets per measure rather than the 9 quarter-note triplets I would have expected. The composer’s intent is perfectly obvious, but I’m still curious—it seems there are a few possibilities here:

1. I am simply wrong, and this is a well-accepted way to notate the rhythm in question
2. Bach (or the editor) has made a mistake and they should be quarter-note triplets
3. Neither of us is wrong, but the proper notation for triplets has changed between the Baroque and now. This was considered entirely correct in Bach’s day.
4. Notation of lots of things was far less standardized then than it is now, and this is simply an example of that. My search for a “proper” notation of triplets in this era is anachronistic in much the same way as a search for the “correct” spelling of English words in the 17th-century would be.

I’m sure there are other possibilities as well. Does anyone know for certain?

Answer 1

I was thinking that it makes it easier to read, because you can easily distinguish the triplets from the quarter notes this way. Then I googled Bach’s Orgelbüchlein and found this Wikipedia page: Orgelbüchlein. Here is a quote from that link from the section on In dulci jubilo:

Bach notated the triplets in the accompaniment as quavers instead of crotchets, to make the score more readable for the organist.

Answer 2

Another example that comes to my mind:

Triplets in the courante of the french suite in Eb have been notated as 3 eighth notes.

You are right:

The composer’s intent is perfectly obvious!

there are a few possibilities here:

I am simply wrong, and this is a well-accepted way to notate the rhythm in question.

Yes.

It seems it has been use to notate triplets throughout a piece this way, probably as abbreviation (like „simile“, maybe for better reading).

Bach (or the editor) has made a mistake and they should be quarter-note triplets.

No.

There is no mistake as the intention is obvious - as you say.**

Neither of us is wrong, but the proper notation for triplets has changed between the Baroque and now. This was considered entirely correct in Bach’s day.

Yes.

This was considered correct, and also in a hand writing (manuscript) of today we would still understand it.

Notation of lots of things was far less standardized then than it is now, and this is simply an example of that.

That’s right.

My search for a “proper” notation of triplets in this era is anachronistic in much the same way as a search for the “correct” spelling of English words in the 17th-century would be.

Also this analogy will fit.